# My Spring Drive accuracy report



## ptran (Jul 5, 2008)

In case anyone's interested, I measured the drift of my Spring Drive watches (all run-in) over the course of 6 weeks and here's what I got:



[ROW][COLUMN]Watch[/COLUMN] [COLUMN]Drift(s)[/COLUMN] [COLUMN]Days[/COLUMN] [COLUMN]s/Day[/COLUMN] [COLUMN]s/Week[/COLUMN] [COLUMN]s/Month[/COLUMN][/ROW][ROW][COLUMN]Chrono Steel[/COLUMN] [COLUMN]9.0[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]0.21[/COLUMN] [COLUMN]1.47[/COLUMN] [COLUMN]6.28[/COLUMN][/ROW][ROW][COLUMN]Chrono Titanium[/COLUMN] [COLUMN]4.5[/COLUMN] [COLUMN]43 [/COLUMN] [COLUMN]0.10[/COLUMN] [COLUMN]0.73[/COLUMN] [COLUMN]3.14[/COLUMN][/ROW][ROW][COLUMN]GMT Champagne Dial[/COLUMN] [COLUMN]6.5[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]0.15[/COLUMN] [COLUMN]1.06[/COLUMN] [COLUMN]4.53[/COLUMN][/ROW][ROW][COLUMN]GMT Grey Dial[/COLUMN] [COLUMN]0.0[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]0.00[/COLUMN] [COLUMN]0.00[/COLUMN] [COLUMN]0.00[/COLUMN][/ROW][ROW][COLUMN]GMT Steel[/COLUMN] [COLUMN]-4.5[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]-0.10[/COLUMN] [COLUMN]-0.73[/COLUMN] [COLUMN]-3.14[/COLUMN][/ROW][ROW][COLUMN]Moonphase 041[/COLUMN] [COLUMN]-3.0[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]-0.07[/COLUMN] [COLUMN]-0.49[/COLUMN] [COLUMN]-2.09[/COLUMN][/ROW]
[ROW][COLUMN]Moonphase 119[/COLUMN] [COLUMN]-3.5[/COLUMN] [COLUMN]43[/COLUMN] [COLUMN]-0.08[/COLUMN] [COLUMN]-0.57[/COLUMN] [COLUMN]-2.44[/COLUMN][/ROW]
I wore the "GMT Champagne Dial" watch almost daily during the trial. The others were on winders. I shall wear the "GMT Grey Dial" next to see if it keeps its accuracy on the wrist.


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## Catalin (Jan 2, 2009)

*Very nice !!!*

Most of the high-quality quartz from Japan that I have seen tends to be set slightly on the descending part of the curve - usually meaning that it is slightly slower when worn - I wonder if that is the case for the SpringDrive ... or if it is rather random ... in any case I would certainly be interested to see the results in 4-6 weeks for both GMT Grey Dial and especially GMT Champagne Dial ...


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## South Pender (Jul 2, 2008)

Boy, that's (or should I say "those are") good data! Nicely-controlled experiment. Could you report back after, say, 13 weeks, giving us a longer time span for rates to stabilize? I wouldn't necessarily expect much difference (per month), but it would be a little more reassuring. One thing that your results seem to suggest is good temperature-insensitivity. The results seem to go against the tendency identified by Catalin (and which I've noticed too) for quartz watches of slower rates for watches that are worn (higher ambient temperature) than for watches off the wrist. At what ambient temperature were the watches on the winders? In any case, great work, and thanks for reporting your results.


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## ptran (Jul 5, 2008)

I've put the titanium chronograph and one of the moon phases back in their "time capsules", but I will monitor the rest and update the thread in another 6 weeks. By that time, I might also have a Galante to add to the mix!

The room temperature for the watches on the winders would have hovered around 23-24 degrees Celsius.


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## webvan (Dec 11, 2008)

Thanks for sharing, and...wow, nice collection! The GMT Grey Dial is still on my list, and if it's the most accurate one, that's even better ;-)


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## RPF (Feb 28, 2008)

Nah. It's the luck of the draw. 

The important thing is this. They all meet spec of +-15s/m between 5-35 C. That's way way superior to the best mechanical GS of +5/-1 s/day. 

Note the variance in the distribution of average drift between the SD movements in a similar environment, in this case, on winder in a room. This is way more informative than any single number presented.

But great data!


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## Davos (May 9, 2009)

I still note the confusion concerning the definition of timekeeping accuracy. Or rather inaccuracy since the point of a test is to return an estimate of timekeeper inaccuracy, that its unpredictable behaviour. Any predictable rate depending only on the time can be subtracted yielding a much more accurate result. This is the reason why the Sun, which has a variable but predictable daily rate ranging between -17s and + 30s, is actually a very accurate chronometer with a yearly inaccuracy of less than 0.5s/year once it has been adjusted for predictable rate. Since any constant rate is predictable, it does not contribute to inaccuracy, so is irrelevant. This is why all official chronometer tests and competitions are done with a declared rate. Or rather, were done, explaining why this simple concept seems to have been completely forgotten.

There is a very good introduction to the analysis of timekeeper inaccuracy here

Philip Woodward, "Measurement of Clock Performance," Chapter 18 of 
A.L. Rawlings, "The Science of Clocks & Watches, Third Edition," British Horological Institute, Upton UK 1993.

This reference is a good start for systematic analysis of timekeeping accuracy and required reading here. 

Davos


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## webvan (Dec 11, 2008)

Yes, if it's predictable it can be corrected, however, for a watch, you don't want to have to remember that you set it 45 days ago so if it gains 1 spd you need to add 45 seconds. Predictable maybe, but not practical !


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## Catalin (Jan 2, 2009)

webvan said:


> Yes, if it's predictable it can be corrected, however, for a watch, you don't want to have to remember that you set it 45 days ago so if it gains 1 spd you need to add 45 seconds. Predictable maybe, but not practical !


Just my thoughts !

The original concept was however very usable in the days when (mechanical) marine chronometers were just that ... but this is the 21st century ;-)


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## South Pender (Jul 2, 2008)

RPF said:


> The important thing is this. They all meet spec of +-15s/m between 5-35 C. That's way way superior to the best mechanical GS of +5/-1 s/day.
> 
> Note the variance in the distribution of average drift between the SD movements in a similar environment, in this case, on winder in a room. This is way more informative than any single number presented.
> 
> But great data!


Interesting! I find the _mean_ drift of the seven watches much more informative than the variance. Sure it (and each specimen) is within the spec. of ± 15 sec./month, but what is so impressive (at least to me) is just how much closer to 0 the mean and each value is. One is within HEQ territory; an additional four are very close (and as good as or better than many 8F Seikos are and the Rolex Oysterquartz was), and even the most deviant is still keeping far better time than what we consider normal quartz performance. That five of the seven are either in or lurking very close to HEQ performance strikes me as phenomenal, since SDs are not thermocompensated. The mean is about +.90, and the standard deviation is 3.75. This is undoubtedly greater variability than we'd see with an A660 or 9F movement, but not enormously greater. 

These numbers yield a .90 confidence interval of about (-1.85, +3.65) sec./month, which means that, if we can assume that (a) the sample is representative of the population of SDs and (b) the 6-week-based monthly values will hold up over a longer trial period, we can infer with 90% probability that the population mean for SD is greater than -1.85 sec./month and less than about 3.65 sec./month. And this tells us a lot about the likelihood of ending up with one that does much worse than that. Of course, these assumptions may well not be fully justified, and the preceding inferential results should be seen as merely preliminary. They are, however, a start.

The other thing, though, that impresses me is the preliminary evidence that these results represent of good temperature-insensitivity. More research is needed on that though through a well-designed study with a number of SDs and varying temperatures.

_Edit:_ I have changed the inferential results as a result of realizing that a two-sided confidence interval is preferable here to a one-sided one.


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## Davos (May 9, 2009)

South Pender said:


> Interesting! I find the _mean_ drift of the seven watches much more informative than the variance. Sure it (and each specimen) is within the spec. of ± 15 sec./month, but what is so impressive (at least to me) is just how much closer to 0 the mean and each value is. One is within HEQ territory; an additional four are very close (and as good as or better than many 8F Seikos are and the Rolex Oysterquartz was), and even the most deviant is still keeping far better time than what we consider normal quartz performance. That five of the seven are either in or lurking very close to HEQ performance strikes me as phenomenal, since SDs are not thermocompensated. The mean is about +.90, and the standard deviation is 3.75. This is undoubtedly greater variability than we'd see with an A660 or 9F movement, but not enormously greater.
> 
> These numbers yield a .90 confidence interval of about (-1.85, +3.65) sec./month, which means that, if we can assume that (a) the sample is representative of the population of SDs and (b) the 6-week-based monthly values will hold up over a longer trial period, we can infer with 90% probability that the population mean for SD is greater than -1.85 sec./month and less than about 3.65 sec./month. And this tells us a lot about the likelihood of ending up with one that does much worse than that. Of course, these assumptions may well not be fully justified, and the preceding inferential results should be seen as merely preliminary. They are, however, a start.
> 
> ...


Regarding actual scientific error analysis of timekeepers, not this (whatever this is), the error usually tends to indicate an underlying distribution with infinite variance such that a single observation is as reliable an indicator as a sequence of observations. In other words, the above statistical analysis of the predictable rate is meaningless except as an empirical study of how Seiko calibrates the rate of its watches.

I find it amazing that you all here ignore the actual research which has been done on accuracy of timekeepers, even after the sources have been given. This use of the word "research" differs from the one used above, which is meaningless if the results are not going to be submitted to a peer reviewed journal. This is not so difficult, the Horological Journal invites authors to publish there: http://www.bhi.co.uk/hj/hj.htm

Davos


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## Catalin (Jan 2, 2009)

1. I would not go as far as to say that we are in the same range as a 'new from JP and working as expected' caliber 8F ...

2. I would say that we have decent info on how precise Seiko calibrates the SDs out of factory (and the results seem to be good), but I would also say that we need more info in regard to the sensitivity to temperature - we basically have no info on how the rate is *for the precise same watch* at 23 C and let's say 29 C - in about 4-6 weeks we should probably know more and possibly have the above metric for two watches ...


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## RPF (Feb 28, 2008)

South Pender said:


> These numbers yield a .90 confidence interval of about (-1.85, +3.65) sec./month, which means that, if we can assume that (a) the sample is representative of the population of SDs and (b) the 6-week-based monthly values will hold up over a longer trial period, we can infer with 90% probability that the population mean for SD is greater than -1.85 sec./month and less than about 3.65 sec./month. And this tells us a lot about the likelihood of ending up with one that does much worse than that. Of course, these assumptions may well not be fully justified, and the preceding inferential results should be seen as merely preliminary. They are, however, a start.
> 
> The other thing, though, that impresses me is the preliminary evidence that these results represent of good temperature-insensitivity. More research is needed on that though through a well-designed study with a number of SDs and varying temperatures.


Nah. There is but one temperature history examined here (they were all in the same room on winder with the exception of one watch)

What we're seeing is the effect of temperature calibration, i.e. each watch is tuned at factory to wrist temperature.

The variance tells us how good the calibration was and nothing about the inherent accuracy of the movement with temperature, which is our singular focus when it comes to HEQ and TC.

Any set of tunable quartz movements rated to +-15 s/m that's properly calibrated can do as well, if not better.

Comparing this set of data to the TC performance data is apples and oranges. The spec of +-10 s/year is 18x tighter than the SD's.


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## RPF (Feb 28, 2008)

Davos said:


> Regarding actual scientific error analysis of timekeepers, not this (whatever this is), the error usually tends to indicate an underlying distribution with infinite variance such that a single observation is as reliable an indicator as a sequence of observations. In other words, the above statistical analysis of the predictable rate is meaningless except as an empirical study of how Seiko calibrates the rate of its watches.
> 
> I find it amazing that you all here ignore the actual research which has been done on accuracy of timekeepers, even after the sources have been given. This use of the word "research" differs from the one used above, which is meaningless if the results are not going to be submitted to a peer reviewed journal. This is not so difficult, the Horological Journal invites authors to publish there: http://www.bhi.co.uk/hj/hj.htm
> 
> Davos


Well, that's why watch forums are also called *hobbyist* havens! Though I have to admit this one subforum is probably THE most technical discussion of horological technology around.

Re: error. How do we define TRUE time? It's not an inherent property. Which is the TRUE clock? We base our readings off an arbitrary network of atomic clocks around the world and accuracy/drift is always compared against a standard that has assumed zero error. In this regard, assumptions of normality is valid, otherwise we won't have accuracy specs from manufacturers.


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## South Pender (Jul 2, 2008)

RPF said:


> Nah. There is but one temperature history examined here (they were all in the same room on winder with the exception of one watch)
> 
> What we're seeing is the effect of temperature calibration, i.e. each watch is tuned at factory to wrist temperature.
> 
> The variance tells us how good the calibration was and nothing about the inherent accuracy of the movement with temperature, which is our singular focus when it comes to HEQ and TC.


Can't agree with that (that the data tell us nothing of value about temperature variation). If, as you say, each watch was tuned at the factory to wrist temperature, why are the watches that have not been on the wrist performing for all intents and purposes at the same level as the one that was on the wrist? To me this suggests less temperature sensitivity than might be expected. I certainly acknowledge that much more research is needed to get at the effects of temperature variation on SD watches, but what we've seen is encouraging and not at all irrelevant.



RPF said:


> Comparing this set of data to the TC performance data is apples and oranges. The spec of +-10 s/year is 18x tighter than the SD's.


I don't follow your mathematical reasoning here. Say that the SDs are actually showing specs of ± 50 sec./year. The numbers we have here are certainly within that range. By what number system does this represent 1/18 the accuracy of ± 10 sec./year?


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## South Pender (Jul 2, 2008)

Davos said:


> Regarding actual scientific error analysis of timekeepers, not this (whatever this is), the error usually tends to indicate an underlying distribution with infinite variance such that a single observation is as reliable an indicator as a sequence of observations. In other words, the above statistical analysis of the predictable rate is meaningless except as an empirical study of how Seiko calibrates the rate of its watches.


Does your comment of "whatever this is" indicate that you have no familiarity with basic inferential statistics? The dead-simple analysis I provided was nothing more than obtaining an interval estimate of a parameter--the latter being of interest. It is obviously (I would hope) incorrect to characterize the error (quantified here as the deviation from perfect agreement with the atomic clock) as having infinite variance. To see this just realize that all examples of SDs will have a finite deviation from zero. And we could go far further than that and infer from the results we've seen here (albeit based on only 7 cases) that a "best" least-squares estimate of that finite variance is 14.0625. Further, there is no way that a single observation taken from a population is anywhere near "as reliable an indicator as a sequence of observations." I would substitute the term "sample" for "sequence" in that quote from your post. Further by "reliable," I would substitute the basic statistical term "efficient," meaning likely to be close to the parameter.



Davos said:


> I find it amazing that you all here ignore the actual research which has been done on accuracy of timekeepers, even after the sources have been given. This use of the word "research" differs from the one used above, which is meaningless if the results are not going to be submitted to a peer reviewed journal. This is not so difficult, the Horological Journal invites authors to publish there: http://www.bhi.co.uk/hj/hj.htm


What was presented above is not only very definitely research, but also far from meaningless just because the results of the analysis are not going to be "submitted to a peer reviewed journal." We don't reserve correct statistical analysis for only journal publications. Application of the simplest of inferential techniques (and I mean the _simplest_) to the excellent data provided by ptran has revealed some important information about what the mean accuracy is in the population of SD watches, and about how much variation we can expect in the distribution of error deviations. This, in turn, sets the stage for some careful estimates of likely accuracy in individual specimens.


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## Catalin (Jan 2, 2009)

South Pender said:


> Can't agree with that (that the data tell us nothing of value about temperature variation). If, as you say, each watch was tuned at the factory to wrist temperature, why are the watches that have not been on the wrist performing for all intents and purposes at the same level as the one that was on the wrist? To me this suggests less temperature sensitivity than might be expected. I certainly acknowledge that much more research is needed to get at the effects of temperature variation on SD watches, but what we've seen is encouraging and not at all irrelevant.


I agree numbers LOOK encouraging but we don't really know how much those will change with temperature - it could be that we'll see a 5-10 seconds/month change - 10 would be really unimpressive and 5 would be in range with most of my 'good' but non-TC quartz - the really impressive feat is when a 5-6 seconds variation is calibrated so that you have like a +2 s/m when you do not wear the watch and a -2 or -3 when you do, and on average when you wear the watch 'normally' you can indeed get under 30 seconds/year for a non-TC quartz ...



South Pender said:


> I don't follow your mathematical reasoning here. Say that the SDs are actually showing specs of ± 50 sec./year. The numbers we have here are certainly within that range. By what number system does this represent 1/18 the accuracy of ± 10 sec./year?


He might be speaking about the GUARANTEED precision of models that are considered OK by the manufacturer ... 15*12 = 180 ...


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## RPF (Feb 28, 2008)

South Pender said:


> Can't agree with that (that the data tell us nothing of value about temperature variation). If, as you say, each watch was tuned at the factory to wrist temperature, why are the watches that have not been on the wrist performing for all intents and purposes at the same level as the one that was on the wrist? To me this suggests less temperature sensitivity than might be expected. I certainly acknowledge that much more research is needed to get at the effects of temperature variation on SD watches, but what we've seen is encouraging and not at all irrelevant.
> 
> I don't follow your mathematical reasoning here. Say that the SDs are actually showing specs of ± 50 sec./year. The numbers we have here are certainly within that range. By what number system does this represent 1/18 the accuracy of ± 10 sec./year?


Let me borrow a graph from Dwjquest.










At 96 F and 55 F degrees, the non-TC 1538 has approx. zero error and outperforms the TC 9Fxx.

We can't tell anything from readings done at a single temperature, which is what this data is all about. We're seeing good calibration, because the cluster size is small.

As for the watch worn on wrist, we can 1) take it out of the data set and 2) retime it on the winder. At the same time, a control should be established with 1) a TC quartz and 2) a non-TC quartz. This should help us test the hypothesis SD is thermally insensitive. As it is, there is insufficient evidence. Ideally, a plot similar to Dwjquest's will settle the debate conclusively.

And you're confusing performance with spec. +-10s/y is 18x tighter than +-15s/m. These are the specs for the 9Fxx/other TC and various SDs as printed on literature.


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## Eeeb (Jul 12, 2007)

Interesting thread. 

Bill's observation the most interesting thing here is the variation shown by 6 identical movements subjected to the same conditions may be spot on. We have never had such data before.

However, I don't buy into the observation the variance is small thus showing good calibration. Well... OK, it is good but it is not great. I find it relatively easy to regulate older quartz (with trimmers) to a smaller range. With a good quartz timer and some patience, you can get a range which is half that given in this data.

If the SD has a trimmer... :think:

Many thanks to ptran for the post!!


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## pmbirner (Sep 20, 2009)

Sorry if I'm bringing down a very edifying and high brow discussion on the accuracy of the SD. I mean no sarcasm or disrespect to the personages here when I ask the following stupid question. Nor do I want to in anyway "dis" the SD. But I have to ask it.:-s

Why didn't Seiko put a HEQ thermocompensated device into the SD? My very rudementary understanding of the SD is that the mechanical end of the watch very cleverly and elegantly powers up some sort of magnet on a wheel that generates an inductive charge which is then conveyed into the integrated circuit and to the quartz crystal. Why didn't they put a thermocompensated quartz crystal in there? Does it take up too much room? Would a thermocompensated crystal not not have made any difference anyway with the mechanical end of the watch having too many variables? Did they want room to upgrade the movement in the future? Just guessing here. Or am I missing the point completely?:think:
Phil


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## RPF (Feb 28, 2008)

Others may disagree but my answer is power. A TC requires a thermistor or a second quartz crystal. The circuitry is in nanowatt territory on the SD. The PR is already 72 hours on a single barrel, way better than most mechanical movements.


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## South Pender (Jul 2, 2008)

RPF said:


> Others may disagree but my answer is power. A TC requires a thermistor or a second quartz crystal. The circuitry is in nanowatt territory on the SD. The PR is already 72 hours on a single barrel, way better than most mechanical movements.


That's a good bet, I think. I started a thread months ago about just this question, and the response was illuminating. The consensus seemed to be that no likely SD buyer would care about this level of accuracy and would be very happy with typical quartz accuracy from what s/he saw as a fundamentally mechanical watch.


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## Catalin (Jan 2, 2009)

RPF said:


> Others may disagree but my answer is power. A TC requires a thermistor or a second quartz crystal. The circuitry is in nanowatt territory on the SD. The PR is already 72 hours on a single barrel, way better than most mechanical movements.


Well, very few will disagree with that (even if some progress WAS done during the last 10-20 years on ultra-low-power and I believe TC might be doable today a decent entry-level around 20 spy ) ;-)

The other reason is that the SD is not marketed by Seiko as a very high-end quartz but more like the most accurate mechanical (with a corresponding price) - they are basically trying to avoid / delay the fate of the original quartz - but is only a matter of time until the chinese will do something very similar first at 500$ and then at 200$ ... the strong point is that SD really does not need so much the extreme finish of the highest-end mechanicals to achieve its precision so a really honest higher-end chinese will work perfectly as well!


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## RPF (Feb 28, 2008)

Catalin said:


> The other reason is that the SD is not marketed by Seiko as a very high-end quartz but more like the most accurate mechanical (with a corresponding price) - they are basically trying to avoid / delay the fate of the original quartz - but is only a matter of time until the chinese will do something very similar first at 500$ and then at 200$ ... the strong point is that SD really does not need so much the extreme finish of the highest-end mechanicals to achieve its precision so a really honest higher-end chinese will work perfectly as well!


I doubt it because it won't sell well. Most people don't know what's a spring drive (or even a mechanical watch). The cost of reverse engineering is also substantial for a product that most people do not care for.

The Chinese will laugh their way to the bank with archaic mechanical movements, including the 2824 which can be copied wholesale with impunity.

I don't anticipate any demand for SD-like movements for years to come when mechanicals are still king of the hill and considered sexy.

The SD was a point of pride to Seiko. IMHO, it's very difficult to make something to that spec, much harder than making a say, 9Sxx mechanical. It'll probably cost more to make outside of Seiko's facilities, due to the absolute quality required. The outstanding patents (around 300) are a big problem too.

Sell a budget version and there'll be no market for it. I suspect it'll be easier to make a smooth sweep quartz with stepper instead.

People don't really care for mechanicals with quartz accuracy.


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## South Pender (Jul 2, 2008)

RPF said:


> Let me borrow a graph from Dwjquest.
> 
> 
> 
> ...


Yes, you're right. I was focusing on empirically-determined performance, rather than published specs. I now see (as Catalin pointed out) that the 18:1 came from the ratio of specs. In my opinion, though, empirical evidence is more interesting than specs. It seems plausible to me that Seiko set the SD spec to ± 15 sec./month because they knew that potential buyers weren't interested in HEQ-level accuracy, but were fascinated with the idea of quartz accuracy from what they saw as a basically mechanical movement. Setting the spec to ± 15 sec./month precludes any disappointment and potential returns because Seiko knows that the SDs will greatly outperform this default spec. Thus, I don't feel that published specs are very useful, and that carefully-gathered empirical evidence is much to be preferred. The evidence that ptran provided allows better estimation of the true performance of the SD movement, and use of simple inferential techniques will allow us--with a little more data--to nail down the important aspects of the distribution of SD rate deviations.

As for dwjquest's graph, it would seem--from your earlier logic that a watchmaker will set a movement to demonstrate zero deviation at wrist temperature--that Omega considered one of the temperatures of 55°F and 96°F wrist temperature. But neither is that. Wrist temperature is somewhere in the 84°F-86°F range, certainly not 96°F. Furthermore, although the data in dwjquest's graph is from one watch, they suggest far greater rate variability as a function of temperature than ptran's data suggest for the seven SDs. It's true that, with the latter data, we are not examining rate variation of a single watch as a function of temperature change, but the small difference between the one worn watch, on the one hand, and the average of the 6 on the winders, on the other, provides us with information--albeit from a different perspective--about the same phenomenon.


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## RPF (Feb 28, 2008)

South Pender said:


> Yes, you're right. I was focusing on empirically-determined performance, rather than published specs. I now see (as Catalin pointed out) that the 18:1 came from the ratio of specs. In my opinion, though, empirical evidence is more interesting than specs. It seems plausible to me that Seiko set the SD spec to ± 15 sec./month because they knew that potential buyers weren't interested in HEQ-level accuracy, but were fascinated with the idea of quartz accuracy from what they saw as a basically mechanical movement. Setting the spec to ± 15 sec./month precludes any disappointment and potential returns because Seiko knows that the SDs will greatly outperform this default spec. Thus, I don't feel that published specs are very useful, and that carefully-gathered empirical evidence is much to be preferred. The evidence that ptran provided allows better estimation of the true performance of the SD movement, and use of simple inferential techniques will allow us--with a little more data--to nail down the important aspects of the distribution of SD rate deviations.
> 
> As for dwjquest's graph, it would seem--from your earlier logic that a watchmaker will set a movement to demonstrate zero deviation at wrist temperature--that Omega considered one of the temperatures of 55°F and 96°F wrist temperature. But neither is that. Wrist temperature is somewhere in the 84°F-86°F range, certainly not 96°F. Furthermore, although the data in dwjquest's graph is from one watch, they suggest far greater rate variability as a function of temperature than ptran's data suggest for the seven SDs. It's true that, with the latter data, we are not examining rate variation of a single watch as a function of temperature change, but the small difference between the one worn watch, on the one hand, and the average of the 6 on the winders, on the other, provides us with information--albeit from a different perspective--about the same phenomenon.


Re: Omega. I was saying ptran's data (as well as my own anecdotal evidence from physical SD specimens owned by others, including friends) indicate a pretty good rate on the wrist, which suggests calibration. So far, many report 1-2 s/m accuracy. They worst I heard was around 4-5 s/m. That's very good for a watch spec-ed to +-15s/m.

I didn't say Omega calibrates their watches to wrist temperature. In fact, they don't even tell you the spec-ed accuracy up front. Note however that the Omega 1538 remained within spec for the temperature band. That's all they're required to deliver, for a movement spec-ed to a ~30s/m band within a 30C band. I.E., 1s/m per degree C.

One more thing. Wrist temperature depends on environmental factors. For example, wearing a watch in the death of winter and on a sunny hot day results in different on-wrist temperatures. 84-86F is too tight a band, and must have been specific to certain conditions. But that's a minor point.

Re: SD outperformance. I don't believe that. I trust specs more. It's unreasonable to expect better because the physics of a non-TC tuning fork quartz at 32khz is a fixed parabola. Unless Seiko is employing TC, there is no reason to expect anything other than that, based on what we have uncovered on this forum. We may see tight calibration at a common temperature but that's about it. 1s/m per degree is the limits of physical and human law.


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## South Pender (Jul 2, 2008)

RPF said:


> Re: Omega. I was saying ptran's data (as well as my own anecdotal evidence from physical SD specimens owned by others, including friends) indicate a pretty good rate on the wrist, which suggests calibration. So far, many report 1-2 s/m accuracy. They worst I heard was around 4-5 s/m. That's very good for a watch spec-ed to +-15s/m.
> 
> I didn't say Omega calibrates their watches to wrist temperature. In fact, they don't even tell you the spec-ed accuracy up front. Note however that the Omega 1538 remained within spec for the temperature band. That's all they're required to deliver, for a movement spec-ed to a ~30s/m band within a 30C band. I.E., 1s/m per degree C.
> 
> ...


Good points. However, I do wonder why Omega would choose to calibrate their quartz movements to zero deviation at temperatures that will never be experienced. I would have thought that Seiko's practice in this respect would be the industry norm. Calibration that would lower the parabola would seem to be the key to much-improved performance at the more usual temperature points--wearing and storing. Your other point about the limits of quartz technology perhaps ignores the fact that there can be variations in the quality of the quartz oscillator (including pre-aging) and, particularly, the way and care with which it's cut. Since SD is Seiko's current pride and joy, and prices are high, is it not possible that they have selected only the best quartz crystals for them, thus improving SD performance beyond standard ± 15 sec./month quartz levels?


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## Catalin (Jan 2, 2009)

RPF said:


> ...
> The SD was a point of pride to Seiko. IMHO, it's very difficult to make something to that spec, much harder than making a say, 9Sxx mechanical. It'll probably cost more to make outside of Seiko's facilities, due to the absolute quality required. The outstanding patents (around 300) are a big problem too.
> 
> Sell a budget version and there'll be no market for it. I suspect it'll be easier to make a smooth sweep quartz with stepper instead.
> ...


I disagree on the first two points - it MIGHT have been difficult to make initially when the ultra-low power was indeed a challenge, but today that is no longer the case.

And as for your opinion on 9S being easier to build MECHANICALLY - I can only say one thing - the Seiko marketing is waaaay too effective on you :-d

The truth is that Seiko has chosen for MARKETING reasons to pair the quartz elements with rather high-end movements to (partially) justify the price - HOWEVER the mechanical part could just as well be VASTLY inferior with very similar final results (and in case you wonder why that sounds familiar - this is just like when the inexpensive japanese quartz has partially destroyed the original over-expensive swiss quartz business model in which the quality needed for a very good product was actually inflated for marketing reasons).

Regarding the last ideas - marketing and availability are strong 'weapons' against weak minds - that is the MAIN reason why we have seen the diminishing interest in quartz and the interest in mechanicals - but make no mistake, that has little to do with technical achievements!


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## Catalin (Jan 2, 2009)

South Pender said:


> ...
> Calibration that would lower the parabola would seem to be the key to much-improved performance at the more usual temperature points--wearing and storing. Your other point about the limits of quartz technology perhaps ignores the fact that there can be variations in the quality of the quartz oscillator (including pre-aging) and, particularly, the way and care with which it's cut. Since SD is Seiko's current pride and joy, and prices are high, is it not possible that they have selected only the best quartz crystals for them, thus improving SD performance beyond standard ± 15 sec./month quartz levels?


The process of flattening the parabola would be more like 'adjusting for temperature' and in most designs that I am aware would be a rather VERY tricky procedure.

The much simpler standard calibration just involves shifting pretty much the same parabola up or down.

I really do not see even Seiko using a quartz cut in SD that is much more advanced than what they already have - and they only have (many-many models and sizes) at 32 kHz and basically one model for the 192 kHz - my feeling is that the second was never seriously considered for power-consumption and volume reasons plus also the fact that it might still need far more complex electronics around it to go to 20 spy - but I might be wrong.


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## South Pender (Jul 2, 2008)

Catalin said:


> The process of flattening the parabola would be more like 'adjusting for temperature' and in most designs that I am aware would be a rather VERY tricky procedure.
> 
> The much simpler standard calibration just involves shifting pretty much the same parabola up or down.


When I wrote "lower the parabola," I meant shifting it (the same parabola) down.


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## RPF (Feb 28, 2008)

Catalin said:


> I disagree on the first two points - it MIGHT have been difficult to make initially when the ultra-low power was indeed a challenge, but today that is no longer the case.
> 
> And as for your opinion on 9S being easier to build MECHANICALLY - I can only say one thing - the Seiko marketing is waaaay too effective on you
> 
> ...


I've not seen another watch circuit in the nanowatt territory. With batteries and other ready sources of power, that has been unnecessary. Why is that trivial today because honestly, it's difficult for me to imagine a need for that kind of power saving?

Technologically, the 300 patents for SD isn't trivial. The filing fees alone run into the millions. It's a big challenge for even the largest conglomerate to accumulate 300 patents, much less for a product that doesn't have a big market.

The only thing separating the 9S from the SD is the technology. However, their absolute quality are comparable because these are high-end Seiko. It's easy to copy the 9S design using CAD and CNC but to do it to the obsessive quality of the 9S (and I've examined them under a loupe) is a task few companies today can deliver consistently. There is much handwork too. For example, the coil in the SD is hand wound because of the extreme density required. I believe you misunderstand me more than the marketing working its magic on me.

As for the price part, why shouldn't Seiko sell the SD at a premium when there's nothing like it? It's the same way LV or any luxury company price their wares. Corner the market and fix the price. I find it strange customers seem to demand watered down versions of Japanese products, which is something I've noticed across the forums. Yet no one ever asks for watered down Rolex or Iphones. The power of branding.

The Japanese edging Swiss horology towards bankruptcy with the advent of quartz is a different story to the SD today, which is 1) a point of pride 2) Seiko's unique edge and 3) likely to remain luxury and exclusive. If we're never going to see a 3135 on a sub $1k watch, why should we expect to see SD in a budget watch, given the amount of investment in time and money to R&D? The quiet revolution is the loudest drumroll Seiko can muster to the world in the years ahead and help her gain prestige, credibility and stay in people's minds when they think expensive.

I don't think Seiko paired quartz with mechanical to justify the cost of SD. After all, a mechanical GS costs about as much as a SD GS, with the quartz not too far behind. They're just high-end watches of very good build and quality, movement notwithstanding. It's my opinion SD is underpriced today.


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## RPF (Feb 28, 2008)

South Pender said:


> Good points. However, I do wonder why Omega would choose to calibrate their quartz movements to zero deviation at temperatures that will never be experienced. I would have thought that Seiko's practice in this respect would be the industry norm. Calibration that would lower the parabola would seem to be the key to much-improved performance at the more usual temperature points--wearing and storing. Your other point about the limits of quartz technology perhaps ignores the fact that there can be variations in the quality of the quartz oscillator (including pre-aging) and, particularly, the way and care with which it's cut. Since SD is Seiko's current pride and joy, and prices are high, is it not possible that they have selected only the best quartz crystals for them, thus improving SD performance beyond standard ± 15 sec./month quartz levels?


Re: Omega. Unnecessary cost. They sell a product rated to perform and does perform to spec. What's wrong with that? Most people don't care for accuracy anyway since Omega sells predominantly mechanical timepieces.

The quality of the oscillator (assuming the same design) has nothing to do with the physics. We may see less variability between specimens and over time but the parabola remains. A better quality crystal doesn't have a flatter curve, just a more consistent one between one crystal to the next measured over time (aging).

As for human law, I'm referring to the limits of warrantied specs and service support. Due to QC and supply chain issues, the specs allow room for variable performance to limit support claims during the warranty.


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## South Pender (Jul 2, 2008)

RPF said:


> Re: Omega. Unnecessary cost. They sell a product rated to perform and does perform to spec. What's wrong with that? Most people don't care for accuracy anyway since Omega sells predominantly mechanical timepieces.


OK, but why would it cost more to calibrate their movements to have the parabola cross the X-axis at, say, 68°F and 86°F than at 55°F and 96°F? And I suppose one could say that there's nothing wrong with having a product perform within quite loose specs, but there is, in my opinion, something wrong (in one sense) with selling a product that could, with minimal effort and expense, be much better.


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## pmbirner (Sep 20, 2009)

Enlightening stuff guys. Thanks.
Phil


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## RPF (Feb 28, 2008)

South Pender said:


> OK, but why would it cost more to calibrate their movements to have the parabola cross the X-axis at, say, 68°F and 86°F than at 55°F and 96°F? And I suppose one could say that there's nothing wrong with having a product perform within quite loose specs, but there is, in my opinion, something wrong (in one sense) with selling a product that could, with minimal effort and expense, be much better.


For one, workmanship is expensive, and reserved for mechanicals, because quartz is trash. For two, the movement may not be tunable, as with most quartz movements made today.

All quartz can easily be made ~10x more accurate today with TC technology (perhaps spec-ed to +-20 s/y) with the addition of a thermistor and digital circuitry. That's trivial in today's world. But we don't see more TC watches today than back in the 90s or even 80s. And they're way more expensive than the technology demands. I suspect the reason why is the same to your question.


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## artec (Oct 31, 2006)

Seiko's claim for the SD is 15 seconds per month. assuming that errors are cumulative, that's 180 seconds per year. But the actual errors, based on Ptran's figures, don't exceed 76 seconds per year....... where did the 50 sec per year come from? It's interesting that many examples of The Citizen run well outside the 5 seconds per year spec (both mine had to go back to Citizen for some massage) but all seven of ptran's fleet are well within their spec.
Despite claiming to be an accuracy freak, I am anxiously awaiting the arrival (due any day) of a GMT SD (SBGE 001) and look forward to seeing how it competes.


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## Citizen fan (Dec 15, 2007)

artec said:


> Despite claiming to be an accuracy freak, I am anxiously awaiting the arrival (due any day) of a GMT SD (SBGE 001) and look forward to seeing how it competes.


Congratulations on your expected arrival. I look forward to the photos. Your Spring Drive GMT seems to be a great compromise where you get the great looks and feel of a mechanical watch with excellent quartz accuracy. I get annoyed when I wear my mechanical Seiko that I really like and then I lose 8 seconds a day.


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## John MS (Mar 17, 2006)

pmbirner said:


> Sorry if I'm bringing down a very edifying and high brow discussion on the accuracy of the SD. I mean no sarcasm or disrespect to the personages here when I ask the following stupid question. Nor do I want to in anyway "dis" the SD. But I have to ask it.:-s
> 
> Why didn't Seiko put a HEQ thermocompensated device into the SD? My very rudementary understanding of the SD is that the mechanical end of the watch very cleverly and elegantly powers up some sort of magnet on a wheel that generates an inductive charge which is then conveyed into the integrated circuit and to the quartz crystal. Why didn't they put a thermocompensated quartz crystal in there? Does it take up too much room? Would a thermocompensated crystal not not have made any difference anyway with the mechanical end of the watch having too many variables? Did they want room to upgrade the movement in the future? Just guessing here. Or am I missing the point completely?:think:
> Phil


I suspect that the quartz component of the timing system will always outperform the electro/mechanical component. In other words I believe that the range of accuracy attained by alternately speeding up and slowing down the spinning rotor will always be wider than theaccuracy of the crystal. Thermocompensation will likely have no impact on displayed accuracy. In the SD setup the generator serves two purposes. When it is used as a braked flywheel it serves the same purpose as the stepper motor in the standard quartz watch configuration. In SD the rotor is in constant motion. In the stepper motor the rotor only moves on command. My sense is that the inherent accuracy of SD is limited because that rotor has to be kept spinning within a narrow range.


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## Catalin (Jan 2, 2009)

John MS said:


> I suspect that the quartz component of the timing system will always outperform the electro/mechanical component. In other words I believe that the range of accuracy attained by alternately speeding up and slowing down the spinning rotor will always be wider than theaccuracy of the crystal. Thermocompensation will likely have no impact on displayed accuracy. In the SD setup the generator serves two purposes. When it is used as a braked flywheel it serves the same purpose as the stepper motor in the standard quartz watch configuration. In SD the rotor is in constant motion. In the stepper motor the rotor only moves on command. My sense is that the inherent accuracy of SD is limited because that rotor has to be kept spinning within a narrow range.


I do not believe so - there is indeed some imprecision related to the actual position of the rotor of let's say 10 out of 360 degrees - however that is non-accumulating - so after making the huge number of rotations needed for one entire year the TOTAL imprecision is still 10 degrees out of billions of degrees rotated - so that is NOT the limit - the limit was that initially there was no way to also put all the many extra electronics needed for real T-C in the nanowatt range, and while today that might be possible - there is ABSOLUTELY no marketing reason for it ....


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## South Pender (Jul 2, 2008)

John MS said:


> I suspect that the quartz component of the timing system will always outperform the electro/mechanical component. In other words I believe that the range of accuracy attained by alternately speeding up and slowing down the spinning rotor will always be wider than theaccuracy of the crystal.


This doesn't seem right, given the reported performance--by many owners--of SD watches. In general, from what I've seen (perhaps 10-12 reports now), performance has usually been in the 2-4 sec./month range, which is far superior to what most ordinary (non-TC) quartz watches deliver. If the electro/mechanical component of SD were degrading the performance of the quartz component, wouldn't we expect just the opposite?


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## Catalin (Jan 2, 2009)

South Pender said:


> This doesn't seem right, given the reported performance--by many owners--of SD watches. In general, from what I've seen (perhaps 10-12 reports now), performance has usually been in the 2-4 sec./month range, which is far superior to what most ordinary (non-TC) quartz watches deliver. If the electro/mechanical component of SD were degrading the performance of the quartz component, wouldn't we expect just the opposite?


Actually the 2-4 sec/month is precisely the accuracy of a well-calibrated non-TC quartz that is kept at a rather constant temperature - I have at least 2-3 in that category myself - normally that is a matter of luck but for two reasons that is less so with SD:

- most big watch brands avoid doing too much (like individual checking the actual accuracy) on their lower-cost models, but SD is anything but low-cost;

- even determined manufacturers have real problems matching the variability of electronic parts in non-TC models against the variability of wearing patterns - however with a SD the vast majority of people will wear it in a VERY regular way any time such a monthly test is done (since otherwise the SD will stop in 3 days or so); even those that do not actually wear it will keep the watch on a winder - which still creates a pattern and temperature very stable and much closer to actual wear.

So the bottom line is that the often described accuracy of SD is nothing paranormal ;-) (and many people have that in models at 1/10 or even 1/100 of the price of a SD - as a result of luck or individual calibration).


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## South Pender (Jul 2, 2008)

Catalin said:


> Actually the 2-4 sec/month is precisely the accuracy of a well-calibrated non-TC quartz that is kept at a rather constant temperature - I have at least 2-3 in that category myself - normally that is a matter of luck but for two reasons that is less so with SD:
> 
> - most big watch brands avoid doing too much (like individual checking the actual accuracy) on their lower-cost models, but SD is anything but low-cost;
> 
> ...


Can't quite buy this. First, I don't believe that 2-4 sec./month is anywhere near typical for a non-TC quartz watch. You speak of a "well-calibrated non-TC quartz that is kept at a rather constant temperature." In this, you identify two things that are not necessarily true of an out-of-the-box SD--well-calibrated and kept at a rather constant temperature. Your supposition that Seiko calibrates their SDs more carefully than they do their non-TC quartzes may or may not be true. However, your analysis of a more constant temperature doesn't seem to hold up well to me. Why would keeping the watch on a winder (presumably at room temperature) even out the temperature more than just laying it down on a desk at room temperature when not wearing it? One would have to think that the temperature pattern of change would be the same for a SD as for a standard quartz watch. Further why would putting a SD on a winder (and thus more closely simulating a wearing condition) make the quartz crystal any more accurate than simply placing a regular quartz watch on a table instead?

My conjecture about the superiority of SD accuracy over that of non-TC quartz includes the possibility that the quartz crystals are better-aged and much more carefully chosen.


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## Catalin (Jan 2, 2009)

South Pender said:


> Can't quite buy this. First, I don't believe that 2-4 sec./month is anywhere near typical for a non-TC quartz watch. You speak of a "well-calibrated non-TC quartz that is kept at a rather constant temperature." In this, you identify two things that are not necessarily true of an out-of-the-box SD--well-calibrated and kept at a rather constant temperature. Your supposition that Seiko calibrates their SDs more carefully than they do their non-TC quartzes may or may not be true. However, your analysis of a more constant temperature doesn't seem to hold up well to me. Why would keeping the watch on a winder (presumably at room temperature) even out the temperature more than just laying it down on a desk at room temperature when not wearing it? One would have to think that the temperature pattern of change would be the same for a SD as for a standard quartz watch. Further why would putting a SD on a winder (and thus more closely simulating a wearing condition) make the quartz crystal any more accurate than simply placing a regular quartz watch on a table instead?
> 
> My conjecture about the superiority of SD accuracy over that of non-TC quartz includes the possibility that the quartz crystals are better-aged and much more carefully chosen.


The part with aging MIGHT still be true, but while we have quite a few reports on SD accuracy I dont't really know of anything even remotely serios on aging (after permanent use).

And the second thing on winder use:

- all the good models that I know of are electric and get a little warm when working; also most people tend to keep those in a decently-warm part of the house; and finally being a closed box the warmth is preserved a little better - so all in one I would expect at least 2-3 extra Celsius than when just taking a watch and leaving it on a cold table;

- the vast majority of the SD accuracy reports are anyway from non-winder use, so even if one winder is 'in the cold' my theory still holds perfectly;

- finally on this point - I believe we are still waiting for a very clear report on the accuracy difference over more than one month of a SD 'on hand' vs. same model 'on winder' - but I am very confident we will see a difference perfectly consistent with a well-calibrated non-TC model.

And regarding the well-calibrated part - that might not be as much a 'manual calibration thing' but a 'newer calibration machine/design' thing coupled with maybe 'much tighter quality control for quartz parts' (which as far as I know are a special order in a very, very small size) - the SD is definitely a much more recent development and the entire DESIGN of the calibration machine is very likely 21st century - while for the vast majority of the 'ordinary' Seiko quartz you can definitely see the 'age of the calibration design' dating back when 15s/month was a very high level (and actually even on the not-so-ordinary 8F made in US - I now had one made in 2000 for more than a month in my possession and finally I could understand why so many people were complaining about that - but believe me, my JP-made 8F56 from 2008 is a different class - I guess also a newer/better calibration machine in that factory ;-) ).


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## Eeeb (Jul 12, 2007)

I like collecting older quartz watches that can be regulated by using a trimmer capacitor. If I can't get them to show less than 2-4 seconds error per month when left in the study in the house, I feel disappointed. 

I am occasionally disappointed, but more often am amazed. For the past month I've left an ESA quartz encased by Heuer on my timing machine in a continuous display of instantaneous error rate. It's error rate max has been -0.11 spd. Normally it about -0.05. When the room gets warmer in the afternoon (south facing windows) the error rate can fall to -0.01 spd. 

Based on my observations of error rates the Spring Drive seems to be with the range of any well regulated quartz.


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## ptran (Jul 5, 2008)

Here are my latest numbers:

Sept 1 to Oct 14
* GMT Champagne Dial worn almost daily
* Others on winders
* Average room temperature 23-24C

```
Watch               Drift (s)  Days  s/Day  s/Week  s/Month
Chrono Steel            9.0     43    0.21    1.47     6.28
Chrono Titanium         4.5     43    0.10    0.73     3.14
GMT Champagne Dial      6.5     43    0.15    1.06     4.53
GMT Grey Dial           0.0     43    0.00    0.00     0.00
GMT Steel              -4.5     43   -0.10   -0.73    -3.14
Moonphase 041          -3.0     43   -0.07   -0.49    -2.09
Moohphase 119          -3.5     43   -0.08   -0.57    -2.44
```
Oct 14 to Dec 1
* GMT Grey Dial worn almost daily
* Others on winders
* Average room temperature 21-22C (it got cool enough to turn on my central heating, which is set to 21C)

```
Watch               Drift (s)  Days  s/Day  s/Week  s/Month
Chrono Steel            7.0     48    0.15    1.02     4.38
Chrono Titanium         1.5     48    0.03    0.22     0.94
GMT Champagne Dial    222.5     48    4.64   32.45   139.06 (**)
GMT Grey Dial           2.0     48    0.04    0.29     1.25
GMT Steel             -10.5     48   -0.22   -1.53    -6.56
Moonphase 041          -9.5     48   -0.20   -1.39    -5.94
Moohphase 119          -8.5     48   -0.18   -1.24    -5.31
```
(**) The GMT Champagne Dial experienced a strange glitch in which it ran +27 s/day fast for several days. It eventually returned to keeping accurate time, but the accumulated error over the measurement interval is quite large as can be seen.


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## South Pender (Jul 2, 2008)

Catalin said:


> The part with aging MIGHT still be true, but while we have quite a few reports on SD accuracy I dont't really know of anything even remotely serios on aging (after permanent use).


Couldn't we also be seeing careful selectivity when it comes to quartz crystals destined for SD models? My understanding is that all quartz crystals are not created equal, so that, given the centrality of SD to Seiko's high-end offerings these days, it seems very likely that a very selective cherry-picking may take place with their crystals. Perhaps it is also possible to design and develop better crystals right from the start, and, if so, Seiko would certainly do this for their SD models (and perhaps GS quartz models).


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## Catalin (Jan 2, 2009)

South Pender said:


> Couldn't we also be seeing careful selectivity when it comes to quartz crystals destined for SD models? My understanding is that all quartz crystals are not created equal, so that, given the centrality of SD to Seiko's high-end offerings these days, it seems very likely that a very selective cherry-picking may take place with their crystals. Perhaps it is also possible to design and develop better crystals right from the start, and, if so, Seiko would certainly do this for their SD models (and perhaps GS quartz models).


I believe there is an automated degree of 'cherry-picking' in industrially making any kind of quartz crystal - but the 'general limits' are most often set on design stage - and my feeling is that a quartz manufacture designed in the 80s might very well be slightly inferior to one designed 20 years later in the 00s - so a new ultra-miniature quartz very recently brought to production might automatically show better results (even if with the right quality control in place, the only difference will actually be in yields). The overall dependency on temperature however will most likely be the same (or in very close range) - so those apparently better results in SD are most likely the consequence of a non-nonsense individual calibration ... which is actually a very good thing, since VERY few people have the means to do anything similar to that ... and in many interesting models that is not possible outside the factory ...


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## South Pender (Jul 2, 2008)

ptran said:


> Here are my latest numbers:
> 
> Sept 1 to Oct 14
> * GMT Champagne Dial worn almost daily
> ...


These are very interesting and useful numbers. If we consider the performance of the GMT Champagne Dial as an outlier in the distribution and compute the _mean absolute deviation from 0_ over the 13 other data points (that is, combining time periods), we get 3.53 sec./month mean absolute deviation for these seven watches over a 3-month period. In terms of the performance I have seen reported for ordinary (non-TC) quartz watches, this SD performance is decidedly superior to that. What makes it even more superior is that 6 of the 7 watches have not benefited from the temperature advantages of being worn, and the one that has shows HEQ TC-quartz performance (mean of .625 sec./month over 3 months, which prorates to 7.5 sec./year). What I'm suggesting here is that if you took 7 regular quartz watches and wore one for 3 months and left the remaining 6 unworn in a temperature of 21-24°C, the mean deviation from 0 departure from perfect time would be a good deal greater than 3.53 sec./month.

Another thing in these numbers that I find interesting is that if we consider 5 of the 6 watches (ignoring the outlier) that have been unworn over the two 1.5-month periods, we find in all cases a slight slowing from the first 1.5-month period to the second. The individual shifts are very small, but the average shift over the 5 is highly statistically significant. Thus, with a relatively-small decrease in temperature in the second 1.5-month period, a small, but significant slowing has occurred. One reason I find this interesting is that, with all of my TC-quartz watches, just the opposite has occurred--that is, they have speeded up slightly when the temperature dropped (as when going from being worn to sitting in a drawer). I have observed this now with three Citizen Chronomasters.


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## South Pender (Jul 2, 2008)

Eeeb said:


> Based on my observations of error rates the Spring Drive seems to be with the range of any well regulated quartz.


I guess the problem I have with this assertion is the term "well regulated quartz." Just what does this mean? Are we referring to special regulation that takes place at the factory before the watch is released for sale? Or is it some after-sale regulation that the owner performs or has performed? If the former, are you suggesting that all quartz watches enjoy this good regulation at the factory, or only higher-priced ones? My basis for comparison between SD and a "standard" quartz watch has been the SD compared with a good-quality (not mall-level) non-TC quartz watch as it is in the watch store. I have relatively-recent Cartier and Omega (DeVille) watches, for example, that don't hold to ± 2-4 sec./month, with the Omega closest at about 5-6 sec./month. But could we expect a regular-grade Seiko, Citizen, Hamilton, etc., to perform as well as we have seen from the SDs?


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## Catalin (Jan 2, 2009)

South Pender said:


> These are very interesting and useful numbers. If we consider the performance of the GMT Champagne Dial as an outlier in the distribution and compute the _mean absolute deviation from 0_ over the 13 other data points (that is, combining time periods), we get 3.53 sec./month mean absolute deviation for these seven watches over a 3-month period. In terms of the performance I have seen reported for ordinary (non-TC) quartz watches, this SD performance is decidedly superior to that. What makes it even more superior is that 6 of the 7 watches have not benefited from the temperature advantages of being worn, and the one that has shows HEQ TC-quartz performance (mean of .625 sec./month over 3 months, which prorates to 7.5 sec./year). What I'm suggesting here is that if you took 7 regular quartz watches and wore one for 3 months and left the remaining 6 unworn in a temperature of 21-24°C, the mean deviation from 0 departure from perfect time would be a good deal greater than 3.53 sec./month.
> 
> Another thing in these numbers that I find interesting is that if we consider 5 of the 6 watches (ignoring the outlier) that have been unworn over the two 1.5-month periods, we find in all cases a slight slowing from the first 1.5-month period to the second. The individual shifts are very small, but the average shift over the 5 is highly statistically significant. Thus, with a relatively-small decrease in temperature in the second 1.5-month period, a small, but significant slowing has occurred. One reason I find this interesting is that, with all of my TC-quartz watches, just the opposite has occurred--that is, they have speeded up slightly when the temperature dropped (as when going from being worn to sitting in a drawer). I have observed this now with three Citizen Chronomasters.


The entire set of data mostly suggests two things:

- SD models are SMARTLY regulated at the factory probably also taking into account the (logical) assumption that people WILL wear them when doing any serious long-term accuracy check ; why the same process does not take place with 'ordinary' quartz models costing 10-100 times less is mostly open for debate but I have certain hints ;-)

- SD models also see a clear (and I would not say any smaller than any other normal 32kHz quartz) dependency on temperature.


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## South Pender (Jul 2, 2008)

Catalin said:


> SD models also see a clear (*and I would not say any smaller than any other normal 32kHz quartz*) dependency on temperature.


What is it in the data that suggests this (the bolded part) to you?


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## Catalin (Jan 2, 2009)

South Pender said:


> I guess the problem I have with this assertion is the term "well regulated quartz." Just what does this mean? Are we referring to special regulation that takes place at the factory before the watch is released for sale? Or is it some after-sale regulation that the owner performs or has performed? If the former, are you suggesting that all quartz watches enjoy this good regulation at the factory, or only higher-priced ones? My basis for comparison between SD and a "standard" quartz watch has been the SD compared with a good-quality (not mall-level) non-TC quartz watch as it is in the watch store. I have relatively-recent Cartier and Omega (DeVille) watches, for example, that don't hold to ± 2-4 sec./month, with the Omega closest at about 5-6 sec./month. But could we expect a regular-grade Seiko, Citizen, Hamilton, etc., to perform as well as we have seen from the SDs?


I have 4 caliber 9000 models all bought in 2009 (and the backs were never opened) - one seems to be around 2-3 sec/month when worn 8/24 and another one in the range 3-4 s/m, while the other two are around 4-6 s/m (but those with very little wear) - and ALL are on the FAST side; so obviously:

a) it is mostly a matter of luck - which is partially to be expected since I paid for all 4 together in the range of 1/10 of the price of a high-end SD;

b) have you ever tried to wear the Omega or the Cartier at least 8/24 for a month ? or as an alternative to leave them in a slightly warmer spot ? I have noted that ALL my decent models except the E510 seem to be clearly happier (even after only one month) on my (slightly warm) wireless router :think:


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## Catalin (Jan 2, 2009)

ptran said:


> Here are my latest numbers:
> ...
> The GMT Champagne Dial experienced a strange glitch in which it ran +27 s/day fast for several days. It eventually returned to keeping accurate time, but the accumulated error over the measurement interval is quite large as can be seen.


I find that glitch by far the most unusual thing in all those results - but actually the entire set of data is very important and relevant to further talk that will certainly take place in this forum and others like it ;-)


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## Catalin (Jan 2, 2009)

South Pender said:


> What is it in the data that suggests this (the bolded part) to you?


Obviously the fact that ALL the models kept on winder in those most recent two tests have shown a (IMHO large but perfectly consistent) change in the range of 2-3 seconds/month by only changing the average temperature with probably less than 3 degrees Celsius - in my E510 that would most likely result in a change under 0.2s/m and in the 8F56 certainly under 0.5s/m.


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## South Pender (Jul 2, 2008)

Catalin said:


> Obviously the fact that ALL the models kept on winder in those most recent two tests have shown a (IMHO large but perfectly consistent) change in the range of 2-3 seconds/month by only changing the average temperature with probably less than 3 degrees Celsius - in my E510 that would most likely result in a change under 0.2s/m and in the 8F56 certainly under 0.5s/m.


OK, but have you perhaps assumed a linear relationship in your conjecture about the E510 and 8F56--i.e., that the changes you have observed in the past would linearly prorate down to the figures you have presented? On another point, haven't you noticed an _increase_ in rate (rather than the decrease seen here with the SD watches) with your HEQ watches when exposed to cooler ambient temperatures?


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## South Pender (Jul 2, 2008)

Catalin said:


> (b) have you ever tried to wear the Omega or the Cartier at least 8/24 for a month ? or as an alternative to leave them in a slightly warmer spot ? I have noted that ALL my decent models except the E510 seem to be clearly happier (even after only one month) on my (slightly warm) wireless router :think:


That's a good idea and one I have been contemplating. I thought I might get a heating pad and leave it plugged in, with the watches on a rack maybe 2 or 3 inches above the surface of the pad. As for the Omega and Cartier, I have worn them very, very little--only for the occasional dressy occasion--and nowhere near 8/24. With a couple of new HEQ additions (one in gold and one in silver), I'm going to sell both.


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## ptran (Jul 5, 2008)

Catalin said:


> I find that glitch by far the most unusual thing in all those results - but actually the entire set of data is very important and relevant to further talk that will certainly take place in this forum and others like it ;-)


I find the glitch rather worrisome. I wonder if there's a faulty electrical contact exposed by the change in temperature/environment, or if there's a bug in the electronics that caused it to hang for a while. The watch is keeping accurate time now, so I'm not sure if I'll be successful pursuing a warranty repair on it... Thoughts?


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## webvan (Dec 11, 2008)

I can't see any good reason for this to happen, I would check with Seiko, when is the warranty running out?

As a side note, which SD do you prefer? I'm dying to get the GMT Silver with its big blue sweeping hand ! I'd say your SDcollection is second to none!


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## Catalin (Jan 2, 2009)

ptran said:


> I find the glitch rather worrisome. I wonder if there's a faulty electrical contact exposed by the change in temperature/environment, or if there's a bug in the electronics that caused it to hang for a while. The watch is keeping accurate time now, so I'm not sure if I'll be successful pursuing a warranty repair on it... Thoughts?


I agree that the warranty might be the first factor in determining what to do next ... if there is not much of it left you should just change the 'wearing plan' a little so as to try to subject the watch to the same scenario - for instance wear it for a week and then put it back where it is now - if the problem appears again I believe an email to Seiko might be needed ...

How was the power reserve before moving that one on winder ? how was it in those days when it was too fast ? and how is now ? Could it still be something like for instance a glitch from the winder - for example if it was not set correctly and was not winding the watch enough, or maybe it was 'shaking' the watch waaay too much (I can see a scenario in which a perfect SD might become slightly inaccurate when 'shaken' at a specific frequency - but to get so many seconds it might need to be shaken at that precise frequency for an hour or more ...)


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## ptran (Jul 5, 2008)

webvan,

My favourite SD is the Galante SBLA033 I recently got (GMT, chocolate brown, ostrich strap). To me, it strongly evokes Jules Verne, both in style and in the unique/unusual hybrid technology.

My least favourite is the metal bracelet GMT SNR009. Over time I grew to dislike the large power reserve "slash". The dial would look so much better with a more subtle power reserve.

I prefer the original moonphase SD (SNR011) over the 2nd design (SNR017). The original looks more opulent in person.

In photos, I thought I would like the newer stainless steel chrono (SPS003) more than the original titanium chrono (SPS001), but on my wrist, the original titanium chrono looks and feels better.

The leather strap GMTs are both really nice. Their dials look much better in person than in photos. The champagne dial, for example, often looks salmon coloured and matte in photos, but it really is "champagne" coloured and glittering metallic in person.

Spring Drives are so well made that you really need to view them in person, and closely, to see the details that will make the difference between like and love. Photos do not capture the craftsmanship and detailing.

Catalin,

There's plenty of warranty left on the watch, so I can still afford to keep it under observation.

While wearing it on my wrist, the power reserve is always pegged at full. It drops by 8 hours each night on the night stand, but after a couple hours of wear it's full again.

When I moved it onto the winder for the 2nd set of measurements, the winder kept it full continuously. The winder rests for only one or two hours between cycles, so it was never more than 2 hours from full.

It was either the 4th or 5th week into the 2nd set of measurements when it started run +27 s/day fast.


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## webvan (Dec 11, 2008)

Thanks for the insight, wasn't aware of the SBLA033, certainly an original design :









I passed on a heavily discounted SNR013 earlier this year and kicked myself for it, but then saw the SNR015 and as you say pictures don't do it justice, I was blown away!


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## John MS (Mar 17, 2006)

South Pender said:


> This doesn't seem right, given the reported performance--by many owners--of SD watches. In general, from what I've seen (perhaps 10-12 reports now), performance has usually been in the 2-4 sec./month range, which is far superior to what most ordinary (non-TC) quartz watches deliver. If the electro/mechanical component of SD were degrading the performance of the quartz component, wouldn't we expect just the opposite?


Several messages back I was arguing that in my mind it would be unlikely that a watchmaker could controlling the revolutions of of a physical object like a spinning rotor as tightly as the oscillations of a quartz crystal could be controlled.

Most buyers of high-end watches (me included) would expect their timepiece would deliver accuracy commensurate with it's price and the competition. For the SD that competition is hiughly accurate quartz timed watches like Seiko GS, Citizen Chronomaster, etc.

I find it strange that Seiko would assign a poor accuracy rating to the SD and yet deliver watches that many owners report that will perform to a tighter standard. I wonder if some of the real-world accuracy observations occur when the watch is not worn daily but stored in one position for an extended period.


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## South Pender (Jul 2, 2008)

John MS said:


> Most buyers of high-end watches (me included) would expect their timepiece would deliver accuracy commensurate with it's price and the competition. For the SD that competition is hiughly accurate quartz timed watches like Seiko GS, Citizen Chronomaster, etc.
> 
> I find it strange that Seiko would assign a poor accuracy rating to the SD and yet deliver watches that many owners report that will perform to a tighter standard. I wonder if some of the real-world accuracy observations occur when the watch is not worn daily but stored in one position for an extended period.


I understand your argument, and you may be right (about the relative difficulty of controlling revolutions of a rotor as opposed to the vibrations of a crystal). However, I don't know that your comment that "Most buyers of high-end watches (me included) would expect their timepiece would deliver accuracy commensurate with it's price and the competition" is consistent with my observations. Don't you think that most buyers of high-end watches (in general) buy them more for the prestige factor and their aesthetics than for accuracy? As for SD, again, I wouldn't consider 2-4 sec./month a "poor accuracy rating," but would add that SD buyers are, I would think, more interested in this new and clever technology (perhaps coupled with the generally high aesthetic quality of the watches that have this technology) than in accuracy per se.


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## webvan (Dec 11, 2008)

Actually Seiko rate the SDs at 1spd, which is not bad, but it's hard to understand why they are being so conservative based on what SD owners are seeing.


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## Catalin (Jan 2, 2009)

John MS said:


> Several messages back I was arguing that in my mind it would be unlikely that a watchmaker could controlling the revolutions of of a physical object like a spinning rotor as tightly as the oscillations of a quartz crystal could be controlled.
> 
> Most buyers of high-end watches (me included) would expect their timepiece would deliver accuracy commensurate with it's price and the competition. For the SD that competition is hiughly accurate quartz timed watches like Seiko GS, Citizen Chronomaster, etc.
> 
> I find it strange that Seiko would assign a poor accuracy rating to the SD and yet deliver watches that many owners report that will perform to a tighter standard. I wonder if some of the real-world accuracy observations occur when the watch is not worn daily but stored in one position for an extended period.


I do not believe Seiko has ever positioned SD against the class of GS quartz and Chronomaster - the marketing IMHO points very clear on positioning SD against the high-end automatic models from companies like Omega and Rolex - but with a MUCH bigger precision compared to those (and with a very clear factor of 'uniqueness' and in-house design which is IMHO somehow similar to that of the co-axial).

I also believe that normal SD owners never bother about whether the accuracy of the SD is in the same league as the Chronomaster or just in the slightly inferior class of the Seamaster Quartz - they are generally happy they get (far) more than ten times better accuracy than a Rolex, with a finish that is most likely superior in many aspects - so we should all appreciate the valuable feedback that we get from those very few owners obsessed with accuracy ... just like us ;-)


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## Eeeb (Jul 12, 2007)

webvan said:


> Actually Seiko rate the SDs at 1spd, which is not bad, but it's hard to understand why they are being so conservative based on what SD owners are seeing.


People might realize the watch was really quartz if they published quartz-level accuracy claims. Seiko wants to keep selling to folks who would never buy a quartz... or, at least, never pay SD prices for a quartz.


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## Pecktime (Dec 10, 2009)

Eeeb said:


> People might realize the watch was really quartz if they published quartz-level accuracy claims. Seiko wants to keep selling to folks who would never buy a quartz... or, at least, never pay SD prices for a quartz.


So true! :-!


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## John MS (Mar 17, 2006)

Catalin said:


> I do not believe Seiko has ever positioned SD against the class of GS quartz and Chronomaster - the marketing IMHO points very clear on positioning SD against the high-end automatic models from companies like Omega and Rolex - but with a MUCH bigger precision compared to those (and with a very clear factor of 'uniqueness' and in-house design which is IMHO somehow similar to that of the co-axial).
> 
> I also believe that normal SD owners never bother about whether the accuracy of the SD is in the same league as the Chronomaster or just in the slightly inferior class of the Seamaster Quartz - they are generally happy they get (far) more than ten times better accuracy than a Rolex, with a finish that is most likely superior in many aspects - so we should all appreciate the valuable feedback that we get from those very few owners obsessed with accuracy ... just like us ;-)


I've only read a few Seiko advertisements and press releases for the 
Spring Drive. But, of those I have not seen a comparison of the quartz timed Spring Drive to a balance wheel timed mechanical movement. Likely because the comparison would be ludicrous. Something like comparing the times of a mid-level race horse to a farmers draft horse in a track race.

SD watch owners may be different from owners of other high-end quartz timed watches in that they don't pay attention to it's accuracy. I would find that unusual in part because many owners of high end watches that I'm familiar with tend to be quite aware of their watch and it's performance. Because the watch is timed with a quartz crystal it's performance should be compared to other quartz timed watches - say the Pulsar PSR 10 or Citizen Chronomaster.

I wonder whether the anecdotal accuracy we read about reflect the results of daily wear. It is certainly conceivable that SD accuracy is impacted by positional variance, and I wonder if some of that variance is being cancelled out by careful storage.


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## Catalin (Jan 2, 2009)

John MS said:


> ...
> I wonder whether the anecdotal accuracy we read about reflect the results of daily wear. It is certainly conceivable that SD accuracy is impacted by positional variance, and I wonder if some of that variance is being cancelled out by careful storage.


There are basically no valid technical reasons why a SD should exhibit positional variance in the easy-to-measure range.

However if you follow the actual values posted in this thread you will note the same kind of thermal variance as in any standard 32kHz non-TC quartz - and I will have to say with very nice and CONSISTENT results ...


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## John MS (Mar 17, 2006)

Catalin said:


> There are basically no valid technical reasons why a SD should exhibit positional variance in the easy-to-measure range.
> 
> However if you follow the actual values posted in this thread you will note the same kind of thermal variance as in any standard 32kHz non-TC quartz - and I will have to say with very nice and CONSISTENT results ...


I think there are some unknowns about the SD performance and positional variance could be one of them. If the movement is left in one position gravity and drag on the spinning rotor will be constant. Change positions and those forces change and the crystal/IC timing circuit will have to recognize the change and initiate a compensating adjustment. Change positions frequently and the circuitry may be in a continual state of playing catch-up. There may also simply be a significant sample to sample variance in performance.

On the one hand we can safely assume Seiko has assigned an error range to the SD that is the result of many hours of their testing and evaluation. On the other hand we have a few SD owners who have provided anecdotal results that indicate a tighter range of error. There has to be a reason for such a disparity. I doubt it is the result of Seiko providing new owners with a surprise gift by delivering a new very expensive watch movement performs much better than specification. That would not speak well of the good design and quality control that Seiko is known for.


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## Catalin (Jan 2, 2009)

John MS said:


> I think there are some unknowns about the SD performance and positional variance could be one of them. If the movement is left in one position gravity and drag on the spinning rotor will be constant. Change positions and those forces change and the crystal/IC timing circuit will have to recognize the change and initiate a compensating adjustment. Change positions frequently and the circuitry may be in a continual state of playing catch-up. There may also simply be a significant sample to sample variance in performance.
> 
> On the one hand we can safely assume Seiko has assigned an error range to the SD that is the result of many hours of their testing and evaluation. On the other hand we have a few SD owners who have provided anecdotal results that indicate a tighter range of error. There has to be a reason for such a disparity. I doubt it is the result of Seiko providing new owners with a surprise gift by delivering a new very expensive watch movement performs much better than specification. That would not speak well of the good design and quality control that Seiko is known for.


First regarding the 'performs much better than expected' part - that seems to be only a PERCEPTION thing - if some owner will keep the same SD on a very good winder for 4 consecutive 1-month tests at a constant 12 Celsius, then 20 Celsius, then 28 Celsius and then 35 Celsius the errors in at least one of the tests will be very likely close to 8-10 seconds/month - and if we have a really unlucky piece we might even see close to 12-15s/month - which is what Seiko guarantees - so Seiko can not promise anything more than that without risking to be proven wrong by a very clear test!!!

Now regarding the mechanical/positional errors - that is almost certainly not the case - and that is a result of how the design of the entire regulation is done - basically you have a permanent magnet which is the rotor and a coil (actually two but we will not go to those optimizations) - the rotor has to spin 8 times/s which means that the electronic circuit will have to see 16 half-pulses every 32768 periods of the quartz - but any decent electronic implementation will not just measure on each spin of the rotor and try to match that to 32768/16 or 32768/8, but instead will keep something like accumulated counters over a very long amount of time - and with that the 'aim' of the circuit (I am vastly simplifying here on how the actual algorithm works) will be so after let's say about 84934656000 quartz ticks (which is 32768 * 3600 * 24 * 30 - so about one month) the number of spins from the rotor (which is on the glide wheel) to be about 8 * 3600 * 24 * 30 = 20736000 (no matter what the friction is, or the power in the mainspring) - at any moment it might be off by even one rotor spin but at the end of the interval that will only mean an error of 1/8 of a second when compared to the 'quartz master' - which however can be itself off probably even close to 10-15s in that interval in the worst case scenario ...


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## South Pender (Jul 2, 2008)

Eeeb said:


> People might realize the watch was really quartz if they published quartz-level accuracy claims. Seiko wants to keep selling to folks who would never buy a quartz... or, at least, never pay SD prices for a quartz.


I don't see this. Seiko _does_ publish quartz-level accuracy claims (see link below).

http://translate.google.ca/translat...0CAsQ7gEwAQ&prev=/search?q=SBGA011&hl=en&sa=G

You'll notice that they clearly state ± 15 sec./month. This is standard, accepted quartz accuracy.

_Note:_ Seiko states the accuracy as ± 15 sec./month _and_ ± 1 sec./day (sometimes in the same description, as above). If we consider accuracy deviations as linearly cumulative, it's hard to reconcile both claims!

I think that the answer to webvan's point about Seiko's accuracy claims being conservative relative to observed accuracy by owners is simply that they don't want purchasers disgruntled because they are not getting the ± 2-4 sec./month accuracy that most people get returning the watches for recalibration. They know that _everyone_ will do better than ± 15 sec./month, and will be happy with this (quartz) level of accuracy in such a beautiful and innovative watch.


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## GX9901 (May 13, 2009)

I've owned my Spring Drive (SNR021) for a solid month now (33 days to be exact). It has gained, to the best of my ability to decipher, just under 3 seconds. During this time, I wore it quite a bit. I think it probably spent around 5 full days off the wrist while averaging maybe 8-10 hours per day on my wrist the rest of the time (this is just an educated guess). Prior to buying the watch, I did some research on Spring Drives and concluded that I should expect it to operate within standard quartz accuracy range. I desired this watch because I was intrigued with the Spring Drive technology and the design of the watch. I didn't expect to get HEQ level accuracy out of this watch. So based on the expectations I had set for myself, I have been totally satisfied with the watch.


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## John MS (Mar 17, 2006)

Catalin said:


> First regarding the 'performs much better than expected' part - that seems to be only a PERCEPTION thing - if some owner will keep the same SD on a very good winder for 4 consecutive 1-month tests at a constant 12 Celsius, then 20 Celsius, then 28 Celsius and then 35 Celsius the errors in at least one of the tests will be very likely close to 8-10 seconds/month - and if we have a really unlucky piece we might even see close to 12-15s/month - which is what Seiko guarantees - so Seiko can not promise anything more than that without risking to be proven wrong by a very clear test!!!
> 
> Now regarding the mechanical/positional errors - that is almost certainly not the case - and that is a result of how the design of the entire regulation is done - basically you have a permanent magnet which is the rotor and a coil (actually two but we will not go to those optimizations) - the rotor has to spin 8 times/s which means that the electronic circuit will have to see 16 half-pulses every 32768 periods of the quartz - but any decent electronic implementation will not just measure on each spin of the rotor and try to match that to 32768/16 or 32768/8, but instead will keep something like accumulated counters over a very long amount of time - and with that the 'aim' of the circuit (I am vastly simplifying here on how the actual algorithm works) will be so after let's say about 84934656000 quartz ticks (which is 32768 * 3600 * 24 * 30 - so about one month) the number of spins from the rotor (which is on the glide wheel) to be about 8 * 3600 * 24 * 30 = 20736000 (no matter what the friction is, or the power in the mainspring) - at any moment it might be off by even one rotor spin but at the end of the interval that will only mean an error of 1/8 of a second when compared to the 'quartz master' - which however can be itself off probably even close to 10-15s in that interval in the worst case scenario ...


You are making a assumption about the design which may or may not be true. The fact is after years of development and testing of the SD Seiko assigned an error rate that one would associate with the least expensive quartz timed watches made. The SD is one of the more expensive quartz timed watches made today. We can only guess at why Seiko feels the SD is not particularly accurate. My guess is that their error rate was based on a large sample of watches over time. I do not buy the argument that Seiko intentionally underrated the watch because it was new. I've never seen that from Seiko or any other watch maker.


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## Catalin (Jan 2, 2009)

John MS said:


> ...
> I do not buy the argument that Seiko intentionally underrated the watch because it was new. I've never seen that from Seiko or any other watch maker.


Oh, we perfectly agree on that !!!


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## webvan (Dec 11, 2008)

That 1spd or 15spm rating is new to me, I'd only ever seen them advertise 1spd...

Maybe the OP could lend one of his SD's to djwquest to see if Seiko are using any kind of "magic" on theur SDs!


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## Catalin (Jan 2, 2009)

webvan said:


> That 1spd or 15spm rating is new to me, I'd only ever seen them advertise 1spd...
> 
> Maybe the OP could lend one of his SD's to djwquest to see if Seiko are using any kind of "magic" on theur SDs!


I do not believe the 'standard timers' can see the SD correctly ... more likely with a custom PC-based setup like the one Moleman had ... but even on that one I would be very curious on what can be measured ...

Oh, and on the 1spd vs 15 spm - that might also be further proof that the long-term counters I was describing could actually go off in one direction or another quite a few rotations of the glide wheel, but probably at the end of a long period the watch will still try to account for it ... and of course it can also be extra-safety from Seiko to limit any complains from waaay too hurried customers ;-)


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## South Pender (Jul 2, 2008)

Catalin said:


> Oh, and on the 1spd vs 15 spm - that might also be further proof that the long-term counters I was describing could actually go off in one direction or another quite a few rotations of the glide wheel, but probably at the end of a long period the watch will still try to account for it ....


I don't understand this. My point above was that if a movement is exhibiting a linearly cumulative rate deviation (from exact time) of 1 second per day (meaning that any rate deviation is not random, but rather consistent in a particular direction), it will be 30 seconds deviant, not 15 sec., at the end of a month. My observations (and those of others too if I'm reading their comments correctly) have been that rate deviation works this way. In all of my watches, whatever the deviation has been after, say, three months has been three times what it was after one month, etc. Sometimes there have been a few small perturbations in the series--for example, only 2.75 the deviation after 3 months as after 1 month, but, with an extension of the series to, say, 6 months, the multiplicative factor is very close, meaning very close to 6 times the one month rate. My one watch that has followed this pattern almost perfectly (with no perturbations to speak of) has been my SD. For example, one month after I began the timing series, it was something like + 3.4 sec. (as closely as I could tell; this is difficult with a sweeping second hand); after two months, it was something like + 6.7; after three months, + 10, etc. For these reasons, the ± 15 sec./month specification (which is seen in many SD descriptions and ads) seems logically inconsistent with ± 1 sec./day.


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## Catalin (Jan 2, 2009)

South Pender said:


> ...
> My one watch that has followed this pattern almost perfectly (with no perturbations to speak of) has been my SD. For example, one month after I began the timing series, it was something like + 3.4 sec. (as closely as I could tell; this is difficult with a sweeping second hand); after two months, it was something like + 6.7; after three months, + 10, etc. For these reasons, the ± 15 sec./month specification (which is seen in many SD descriptions and ads) seems logically inconsistent with ± 1 sec./day.


I guess that the 'difference' makes some sense only from 1 day to 1 month, not from 1 month to 3 months - the idea being that for one day if ALL errors (and I mean every single possible error) accumulates ONLY in one direction you can see for that day an error of 1s - but the probability to have ALL those errors keeping accumulating ONLY in that direction for 1 month is something so unlikely that it can be safely ignored (unless of course there is a real problem with the watch).


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## John MS (Mar 17, 2006)

Catalin said:


> Oh, we perfectly agree on that !!!


Hooraay! :-!


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## South Pender (Jul 2, 2008)

Catalin said:


> I guess that the 'difference' makes some sense only from 1 day to 1 month, not from 1 month to 3 months - the idea being that for one day if ALL errors (and I mean every single possible error) accumulates ONLY in one direction you can see for that day an error of 1s - but the probability to have ALL those errors keeping accumulating ONLY in that direction for 1 month is something so unlikely that it can be safely ignored (unless of course there is a real problem with the watch).


Well, wouldn't that assume a certain random off-setting (bidirectional) pattern of rate errors? If, instead, errors are always in the same direction, then it seems to me that we wouldn't expect this. However, maybe what we have--consistent with your explanation--is a lesser pattern of perturbations that can augment or reduce the consistent rate deviation over short periods of time. Along these lines, here's a paragraph from the Citizen Chronomaster manual that may be getting at much the same thing:

The monthly accuracy of this watch cannot always be determined simply by dividing the annual accuracy of ± 5 seconds by 12. Monthly accuracy may differ by approximately ± 2 seconds depending on conditions of use (such as temperature changes between seasons), amount of time the watch is worn, and other factors.

And, as you've said several posts back, maybe it is to guard against the obsessive-compulsive rate-checkers (like me) concluding after one day that the watch is out of spec, when all that's happened is that the initial sync'ing with the atomic clock was off a little or there was a sudden large temperature change. ;-)


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## Mechanikus (Mar 8, 2008)

First of all let me wish all of you Merry Christmas!

Then I congratulate *ptran* to the gorgeous collection of Spring Drives.

Finally I would like to contribute with my experience.

I have one SD:
http://www.mechanikus.hu/w_GSSD.htm

I am also bit accuracy addict:
http://www.mechanikus.hu/_p_accuracy.htm

I have been testing some watches (100 pieces / cca. 21 th samples) and developed my definitely amateur - in the sense having no specialized laboratory so measure with what you have and use your brain - method:
http://www.mechanikus.hu/_p_rank.htm#methods

My Spring Drive accuracy test was very simple: wore it for 2 years and checked against radio-controlled clock in Germany.
That is what I have found:
http://www.mechanikus.hu/sta_GSSD.htm

My point of interest was where is Spring Drive in terms of accuracy compared to other important watches:
http://www.mechanikus.hu/_p_rank_compare.htm


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## webvan (Dec 11, 2008)

Wow, impressive work, thanks for sharing !


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## Hans Moleman (Sep 24, 2007)

Very impressive indeed.
Thanks for putting all this time into the research.

The start stop effect caught my eye.



> I have also met another phenomena what is not in the focus the *stop and restart effect*. Obviously for different reasons but it can be experienced at mechanical and electrical watches as well. What we can see is that having tested a watch for a reasonable period of time what allows to analyse the average and standard deviation of daily deviations if the watch is stopped for some days after restarting it the average of the new run of tests can be quite far from the average of the previous run while the standard deviation remains more or less the same.


That is an amazing observation.
Could an oscillator have a range of own frequencies?
It just happens to settle on a frequency within that band?

If that were the case all calibration needs to be done on running watches only.
I know that an oscillator needs time to resettle after a restart. You are taking it a bit further though in stating that it settles on another frequency. Who knew?


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## Mechanikus (Mar 8, 2008)

Hans Moleman said:


> Very impressive indeed.
> Thanks for putting all this time into the research.
> 
> The start stop effect caught my eye.
> ...


I am happy that you have found it interesting.

First I realised stop/restart effect at a mechanical a Poljot deck watch
http://www.mechanikus.hu/sta_PDW.htm

Another mechanical example when my wife wore Helvetia just for a day and that changed the characteristic of the watch:
http://www.mechanikus.hu/sta_Hel_2.htm

The first electric encounter of stop/restart effect with Bulova Accutron Masonic after battery replacement:
http://www.mechanikus.hu/sta_BAM.htm
I did not analyse it fully, but when another Accutron produced the same:
http://www.mechanikus.hu/sta_BAIN.htm
I did the analysis.

Finally Seiko just shows the first signs:
http://www.mechanikus.hu/sta_SKAR.htm

In case of tuning forks and quartz watches my impression is that the new battery or the bit different capacitor may change the parameters of the control loop.


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## Mechanikus (Mar 8, 2008)

webvan said:


> Wow, impressive work, thanks for sharing !


That is my pleasure.
I have also published it in Hungarian watch magazine. When I have time I will translate and share it.


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## BenL (Oct 1, 2008)

webvan said:


> Wow, impressive work, thanks for sharing !


+1

This is great stuff. Thanks so much.


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## Eeeb (Jul 12, 2007)

Thanks. I seem to remember discussing this site several years ago but it must have evolved some


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## artec (Oct 31, 2006)

With all due respect, ".... will be very likely....." doesn't seem a very scientific test result.... while you may well be right, and I have no data that points otherwise, do you have evidence to support the "very likely"? I'm sure I haven't seen everything about SD accuracy data but I don't remember seeing any data on temperature effects.

I think most people understandably equate the 15 sec per month specification to how they can expect the watch to perform as it is worn on a more or less day to day basis, and in those terms, SDs in general do seem to perform better than spec.



Catalin said:


> First regarding the 'performs much better than expected' part - that seems to be only a PERCEPTION thing - if some owner will keep the same SD on a very good winder for 4 consecutive 1-month tests at a constant 12 Celsius, then 20 Celsius, then 28 Celsius and then 35 Celsius the errors in at least one of the tests will be very likely close to 8-10 seconds/month - and if we have a really unlucky piece we might even see close to 12-15s/month - which is what Seiko guarantees - so Seiko can not promise anything more than that without risking to be proven wrong by a very clear test!!!
> 
> Now regarding the mechanical/positional errors - that is almost certainly not the case - and that is a result of how the design of the entire regulation is done - basically you have a permanent magnet which is the rotor and a coil (actually two but we will not go to those optimizations) - the rotor has to spin 8 times/s which means that the electronic circuit will have to see 16 half-pulses every 32768 periods of the quartz - but any decent electronic implementation will not just measure on each spin of the rotor and try to match that to 32768/16 or 32768/8, but instead will keep something like accumulated counters over a very long amount of time - and with that the 'aim' of the circuit (I am vastly simplifying here on how the actual algorithm works) will be so after let's say about 84934656000 quartz ticks (which is 32768 * 3600 * 24 * 30 - so about one month) the number of spins from the rotor (which is on the glide wheel) to be about 8 * 3600 * 24 * 30 = 20736000 (no matter what the friction is, or the power in the mainspring) - at any moment it might be off by even one rotor spin but at the end of the interval that will only mean an error of 1/8 of a second when compared to the 'quartz master' - which however can be itself off probably even close to 10-15s in that interval in the worst case scenario ...


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## Hans Moleman (Sep 24, 2007)

This is what I found about powering off a quartz oscillator.



> All OCXOs reach their final stability after some days of operation. To achieve maximum stability, the OCXO should not be turned off since it will take some time until the OCXO reaches the final frequency. Furthermore the final frequency is different from the frequency before turn-off of the oscillator. This retrace problem is well known by all manufacturers and might cause problems after a long power-off time e.g. measurement equipment, which is turned off for weeks.


http://www.kvg-gmbh.de/71.0.html?&L=3

Mechanikus, you were spot on!


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## Mechanikus (Mar 8, 2008)

Eeeb said:


> Thanks. I seem to remember discussing this site several years ago but it must have evolved some


You have perfect memory. I posted some notes mid-2008 then I had a busy time in my professional life I could not regularly visit the Forum. Now I am back. 
Obviously my interest in technology resulting in accuracy is the same.


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## Catalin (Jan 2, 2009)

Mechanikus said:


> First of all let me wish all of you Merry Christmas!
> 
> Then I congratulate *ptran* to the gorgeous collection of Spring Drives.
> 
> ...


I have a curiosity on your measuring methodology - how often do you measure the time on the models that you have under tests and how is your procedure for doing that ?


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## Mechanikus (Mar 8, 2008)

Catalin said:


> I have a curiosity on your measuring methodology - how often do you measure the time on the models that you have under tests and how is your procedure for doing that ?


On that page
http://www.mechanikus.hu/_p_rank.htm

in section Methodology you find details and even the test protocol in XL, but the most important facts:

How often?
Mechanical (including Spring-Drive), tuning fork, balance-wheel watches daily. Old quartz as Omega 1301 (8192 Hz) are also checked also daily.
Modern quartzes monthly.

Procedure 
I read the difference of the time on tested watch and the Radio-controlled clock. I record it and calculate the daily/monthly difference.
Those differences are the basic data the daily / monthly deviation. I calculate the average and standard deviation of the daily / monthly values.

About SD.

What you can see on http://www.mechanikus.hu/sta_GSSD.htm

The chart of daily deviations shows that the daily difference values varied between 0 and 1. Since the dial is not very big I did not guess 1/2 or 1/3 second just recorded the day when the next second was clearly reached.

I just see that the above sentence I have to insert into methodology. Thanks.


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## South Pender (Jul 2, 2008)

Very interesting work, Mechanikus. I do, however, have questions about your methodology. Unfortunately, in your analyses of daily accuracy (with the Spring Drive), you have treated the measurement as a dichotomous variable (0, 1), and your standard deviation estimate will be much larger than is truly the case. Presumably you used some decision rule like: if less than .5 sec., record 0; if more than .5 sec., record 1. But daily deviation is not a binary variable, is it? You can see the distortion in st. dev. estimates when comparing that for the day figures with that from the monthly figures, where the latter is only 1.72 times the former. In actual fact, the st. dev. of daily deviation will be much lower than .4504. One also wonders about the mean daily deviation, with the data measured so imprecisely, but the effects with the mean will be much less than with the st. dev.

I was also wondering whether you were defining deviation as the _algebraic or absolute_ difference between "hh:mm:ss displayed on reference clock and xx:yy:zz shown on tested watch." I wondered about this particularly with your daily measurements since not one, over 730 days, was negative in your graph.


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## Mechanikus (Mar 8, 2008)

South Pender said:


> Very interesting work, Mechanikus. I do, however, have questions about your methodology. Unfortunately, in your analyses of daily accuracy (with the Spring Drive), you have treated the measurement as a dichotomous variable (0, 1), and your standard deviation estimate will be much larger than is truly the case. Presumably you used some decision rule like: if less than .5 sec., record 0; if more than .5 sec., record 1. But daily deviation is not a binary variable, is it? You can see the distortion in st. dev. estimates when comparing that for the day figures with that from the monthly figures, where the latter is only 1.72 times the former. In actual fact, the st. dev. of daily deviation will be much lower than .4504. One also wonders about the mean daily deviation, with the data measured so imprecisely, but the effects with the mean will be much less than with the st. dev.
> 
> I was also wondering whether you were defining deviation as the _algebraic or absolute_ difference between "hh:mm:ss displayed on reference clock and xx:yy:zz shown on tested watch." I wondered about this particularly with your daily measurements since not one, over 730 days, was negative in your graph.


Thanks for your interest in my work. Your remarks are well targeted and worth to be thought over.

Let me start with the last one what is a fact. The behaviour of my Spring Drive was a strictly monotonous increasing function: a clear drift gaining time. Actually I find that it is the second best behaviour of a watch. The best would have been the constant 0 deviation.

Regarding my decision that I do not split a second in my tests.

There are several reasons, but the most important one is practical: although there is a measurement set-up in my mind with high speed camera taking pictures upon the signals of reference clock then analyse the angle of the second hand between the two second signs of the dial to define the fraction of second, but sorry to say I do not have the means to do that.

Obviously I tried with my eyes only. It worked only with dial size of 2.5-3 inches like aircraft clocks and the deck-watch at regular dial sizes reading out fraction of second is simply not reliable.

I had two choices:
1./ Doing nothing.
2./ Study with imperfect set-up but keeping the scientific rules and keeping in mind that my experiences can only be compared among themselves.

The practical decision had a big advantage: besides my fulltime job on that simple way I could manage to record data of several watches in parallel using only a reasonable amount of time for that.

Actually I think that the difference between the monthly and daily st.dev. values can only partially be related to the readout method the equally or more important element is the number of data used to calculate the standard deviation. 
That is why on one hand I set an admission criteria of one year for quartz and 50 days for mechanicals on the other hand I studied the convergence of the best data as well.

Being engineer as first graduation I understand that any modelling - including decisions about measurement method - is imperfect but there are two goals to follow control/minimise the effect of imperfection and compare only comparable data (apple to apple).

I evaluate my results as they deserve: interesting figures describing relationships inside their own circle.


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## South Pender (Jul 2, 2008)

^^Understood. We _do_ have to work with the tools we have, and your results are really valuable. As for the difference in standard deviations, once a reasonably large sample has been gathered (as is the case with your data), there is practically no relationship between magnitude of St. Dev. and number of data points on which it was calculated.


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## Catalin (Jan 2, 2009)

Mechanikus said:


> ...
> There are several reasons, but the most important one is practical: although there is a measurement set-up in my mind with high speed camera taking pictures upon the signals of reference clock then analyse the angle of the second hand between the two second signs of the dial to define the fraction of second, but sorry to say I do not have the means to do that.
> ...


I believe another member of this forum has already used something similar to that with very promising results.

IMHO the absolute best results will be by using:

a) a fast (>1 GHz) PC connected to the internet on a decent connection and synchronized to one of the major internet time servers just before the tests (this probably provides better than 10 milliseconds errors on the time on the computer);

b) a decent 'watch program' on the computer that will display the time including some fractions of a second in a very careful way (so as to always have very constant and small delays); unfortunately none of the major operating systems around are not even soft-realtime but I have modified one of my own programs on Windows and I believe the errors are in the same 10-20 ms interval and more important - very constant;

c) a decent display with better than 60Hz refresh rate

d) a decent camera that can do 25 (maybe even 50) frames/s

e) a program that can display the movie from the above camera 'frame by frame'.

With all the above I believe you can easily measure with a precision better than 100 milliseconds (and even down to the actual time for each frame on the camera) - of course probably nothing better than 10 ms but even at 100 ms the results will be more than 10 times better than what we normally get with a 'human eye' ... I plan on testing with the above setup from January like 4 of my HEQs and I will keep you posted on that ...


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## artec (Oct 31, 2006)

While this may be viewed as a bit off-topic in terms of most of the recent comments, it's still relevant to SD accuracy in general......

I'm wondering to what extent the accuracy of the SD can be attributed to the use of the quartz timing system that replaces the escapements used by Seiko in their high end mechanicals versus any improvements in the SD's gear-train (the part of the works that doesn't replace the escapement). The COSC chronomater spec for mechanicals is -4/+6 sec a day, I believe, and I haven't seen daily variations for an SD that are as large as that. I think I know the answer but I'd be interested in the views of others who are more familiar with mechanicals than I am (not very difficult!).

Not many of the high end mechanicals that one sees tested in the magazines are within COSC figures, which seems to argue that most of the excellent results reported for SDs are due to the improvement delivered by the quartz and glide-wheel. 

Another question that occurs to me is whether the reduced effect of gravity on the glide-wheel and its brake by comparison with the same effect on the balance-wheel and escapement is responsible for the improvement in the SD's time-keeping over other mechanical movements.

And finally, does anyone know whether the strictly mechanical part of the SD movements is the same as that used in the other high end mechanical movements used by Seiko, or is an upgrade?

My SBGE 001 has gained a tad under two seconds since December 22nd, equivalent so far to about 3 seconds a month. No grumbles!


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## Frenchyled (Oct 14, 2007)

Good questions Artec...
I am like you, I want to understand. 

I have two Spring Drive, one SNR001 and one GS SBGE009..the two have not exactly the same precision after about 8 weeks :
SNR001 : - 3s
SBGE009 : -4s

But it is really nice that in about one week it is impossible to see +/- 1s where some quartz and all mechanicals are worst.
Even my Citizen Chronomaster is not so good. (but I thing it's a problem  )


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## Catalin (Jan 2, 2009)

Frenchyled said:


> Good questions Artec...
> I am like you, I want to understand.
> 
> I have two Spring Drive, one SNR001 and one GS SBGE009..the two have not exactly the same precision after about 8 weeks :
> ...


If you have a Citizen Chronomaster which is worse than a second/week I believe it is a huge problem :-d


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## artec (Oct 31, 2006)

I agree with Catalin.... if your The Citizen (I promised ppaulusz not to call them Chronomaster!) is worse than 1 sec per week, it is misbehaving. If you bought it new or if it's still in warranty, you can send it back to Citizen in Japan via Higuchi or Seiya or whomever you bought it from for them to massage it and soothe its troubled brow.

I've done that with two of them, though they weren't nearly as bad as a second a week..... more like 15 or 20 seconds a year. The first one I sent back has now gained a little over a second since July 22nd last year.



Frenchyled said:


> Good questions Artec...
> I am like you, I want to understand.
> 
> I have two Spring Drive, one SNR001 and one GS SBGE009..the two have not exactly the same precision after about 8 weeks :
> ...


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## Frenchyled (Oct 14, 2007)

I own this The Citizen  since 1st of May 2007 and already returned it for the same problem (more than 1s a week) in december 2007 but it seems the problem was not corrected  
I asked Katsu and he told me to wait the fifth year before returning it a second time to him, so I am waiting 2012 impatiently


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## webvan (Dec 11, 2008)

ptran said:


> (**) The GMT Champagne Dial experienced a strange glitch in which it ran +27 s/day fast for several days. It eventually returned to keeping accurate time, but the accumulated error over the measurement interval is quite large as can be seen.


How has the GMT Champagne been behaving? Still don't own an SD...came across a gently used SNR011 for a decent price (€2.8k) sort of tempted...


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## ptran (Jul 5, 2008)

webvan said:


> How has the GMT Champagne been behaving? Still don't own an SD...came across a gently used SNR011 for a decent price (€2.8k) sort of tempted...


It's been keeping good time since. Gained three seconds relative to NIST over the three winter months (Dec/Jan/Feb).


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## artec (Oct 31, 2006)

ptran said:


> It's been keeping good time since. Gained three seconds relative to NIST over the three winter months (Dec/Jan/Feb).


I bought an SBGE 011 and sold my SBGE 001. Although I really liked the 001, it just seemed too big.
I got the 011 on February 12th and set it that day. It's now April 2nd, exactly seven weeks and I can't detect any drift at all. I check it every morning against the 24/7 time signal from WWB and you could set WWB by the SD! Amazing! I know it's only a matter of luck and statistics, but it's still amazing!


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## South Pender (Jul 2, 2008)

artec said:


> I bought an SBGE 011 and sold my SBGE 001. Although I really liked the 001, it just seemed too big.
> I got the 011 on February 12th and set it that day. It's now April 2nd, exactly seven weeks and I can't detect any drift at all. I check it every morning against the 24/7 time signal from WWB and you could set WWB by the SD! Amazing! I know it's only a matter of luck and statistics, but it's still amazing!


Absolutely fabulous, Artec! Can you tell us your wearing pattern with this watch? I found my SD to do better _off_ the wrist and at room temperature (say 68-72° F, and wound every 2-3 days) than on.


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## ptran (Jul 5, 2008)

I haven't graduated to a Grand Seiko yet. The SBGE's do look fabulous.

I find that my SDs run slightly faster at wrist temperature than at room. The difference isn't huge, around -0.07 s/day off the wrist vs on.


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## South Pender (Jul 2, 2008)

ptran said:


> I haven't graduated to a Grand Seiko yet. The SBGE's do look fabulous.
> 
> I find that my SDs run slightly faster at wrist temperature than at room. The difference isn't huge, around -0.07 s/day off the wrist vs on.


Well, that's pretty close to what I found with my one SD. The difference between rate when worn and rate when stored at room temperature was -1.8 sec./*month *with my SD (SBGA011). This corresponds reasonably closely to your result of -.07 sec./day, which would be about -2.1 sec./month.


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## nathantw666 (Aug 6, 2007)

I have nothing to add other than WOW! I LOVE YOUR WATCH COLLECTION!



ptran said:


> In case anyone's interested, I measured the drift of my Spring Drive watches (all run-in) over the course of 6 weeks and here's what I got:
> 
> 
> 
> ...


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## webvan (Dec 11, 2008)

Catalin said:


> First regarding the 'performs much better than expected' part - that seems to be only a PERCEPTION thing - if some owner will keep the same SD on a very good winder for 4 consecutive 1-month tests at a constant 12 Celsius, then 20 Celsius, then 28 Celsius and then 35 Celsius the errors in at least one of the tests will be very likely close to 8-10 seconds/month - and if we have a really unlucky piece we might even see close to 12-15s/month - which is what Seiko guarantees - so Seiko can not promise anything more than that without risking to be proven wrong by a very clear test!


Thought I'd bump this up to see if there is more data available now? I'm still intrigued that most SD owners see +/- 2 spm accuracy, worn or unworn, when there is no logical reason that this can be achieved by a 32Khz non TC quartz. You can't even really argue it's precise tuning as the variations between room and worn should generate significant variations based on what we know of 32Khz movements, something like 40/50 spy at best.

Also, the formatting of the original tables seems to have been messed up by the recent migration, would be great if the OP could fix it ;-)


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## Eeeb (Jul 12, 2007)

Self reported incidental accuracy data is prone to reporting skew. People with worse than normal numbers don't tend to brag about it... I suspect that is operating here. But we won't know until we get some more controlled data.


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## webvan (Dec 11, 2008)

Yes it would be nice to have some results in a an environment with some control, I'd need to get the mini-fridge and an SD...you already have the fridge ;-)


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## Catalin (Jan 2, 2009)

Eeeb said:


> Self reported incidental accuracy data is prone to reporting skew. People with worse than normal numbers don't tend to brag about it... I suspect that is operating here. But we won't know until we get some more controlled data.


Definitely true!

However I would also add the fact that wearing very often a quartz watch will 'stabilize' it a lot - I have seen that in my kinetic which is surprisingly consistent (but being more than ten times less expensive than a SD the factory calibration was in a clearly lower class).


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## webvan (Dec 11, 2008)

Glad I found this thread again !

Got a GMT SD earlier this year, the beautiful SNR015 and it's performed extremely well : 
- Room temperature : +12 spy
- Warm (placed on a router) : +39 spy

So a difference of 27 spy, or 0.074 spd and rereading the messages above I see that ptran had noted a speed increase of 0.07 spd too.

Not on par with TC watches but clearly competitive with the high frequence 262Khz movements (Seiko 8Fxx and Bulova/Citizen Precisionist). Now the question is, how do Seiko do it and why do they only rate it at +/- 15 spm...


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## Leirbag Paey (Oct 21, 2011)

my Spring Drive GMT is still in sync with my iPhone after over a year

wear it almost everyday and it's never seen the insides of a winder


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## videogameland (Oct 24, 2011)

hmm :think: :think: :think:


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## agentdaffy007 (Apr 12, 2012)

I am going to revive this thread. Just wondering what kind of accuracy people are now getting with their Spring Drive watches!

What's the wearing pattern?


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## Eeeb (Jul 12, 2007)

agentdaffy007 said:


> I am going to revive this thread. Just wondering what kind of accuracy people are now getting with their Spring Drive watches!
> 
> What's the wearing pattern?


Spring Drives are non-compensated quartz timed watches. One whose calibration is matched to its average ambient temperature can achieve, like any quartz so calibrated, on the order of one or two seconds per month. You can scan the various threads on the topic but most do not achieve this level.

To the extent that wearing patterns cause variance in the average ambient temperature, they will cause variance in accuracy. Wearing usually causes a higher ambient temperature.

The average ambient temperature will vary from person from location and over time. So a very precise calibration can not be pre-made by Seiko.

Based on reports it appears Spring Drives probably have been made with aged crystals (causing less variance due to aging which is worst when new) and have been more carefully calibrated than the typical Seiko quartz.

I guess that is a Microsoft answer - lots of information but not really what you wanted to know. LOL


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## webvan (Dec 11, 2008)

Probably aged and hand picked too, mine is close to a TC watch -> https://www.watchuseek.com/f9/my-spring-drive-accuracy-report-316507-12.html#post4381643


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## PJ S (Apr 29, 2013)

Rather than re-write it all, have a wee read here.


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## clweb (Feb 17, 2015)

Eeeb said:


> Self reported incidental accuracy data is prone to reporting skew. People with worse than normal numbers don't tend to brag about it... I suspect that is operating here. But we won't know until we get some more controlled data.


I have not so good results, but acceptable. I have my SBGA011 since 12 weeks and it has +18seconds during this time. It is within the specs (15s/month) and good on a dayly basis (0.21s/24h).
Maybe it will change with time, as the watch is brand new from Japan.


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