Seiko 7A38 - by the numbers



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Forum Home > In the beginning there was Seiko Quartz - the World's First .... > Seiko Twin Quartz

Posts: 59

As things turned out, +/-15 seconds per month was good enough for most people (even our host). But during the 1970s, Seiko (and others) continued to innovate and push for greater accuracy. By the mid 1970s, the 4883 movement claimed an accuracy of 1 second per month. Even in the 1978v2 catalogue, the 4883 is still hanging around; but it no longer receives star billing. There is a new top model and it's a twin (quartz)!



The two crystals provided a means of thermocompensation to achieve greater accuracy. There is some discussion of the technicalities out there in the forums - starter for 10:


Between 1978 and 1980, a profusion of calibres emerged across five different series:

Series       Calibre  Secs/Yr    Branding                 Functions
92 (Daini)925610Grand QuartzDay, Date
1978922310King QuartzDay, Date

99 (Suwa)99835SuperiorDay, Date
197899805SuperiorTime only

994310Grand Quartz Day, Date

994210Grand Quartz

994010Grand Quartz
Time only

992320King Quartz Day, Date

992120-Time only

992020-Time only

97 (Daini)972320King Quartz
Day, Date
1979972220King Quartz

972120King Quartz
Time only

972620King Quartz

Day, Date, Independent hour hand

96 (Daini)96825SuperiorDate?
198096815SuperiorTime only

966110CredorTime only

964220-, King QuartzDate

964120-, DolceTime only

94 (Suwa)94835SuperiorDay, Date
198094815SuperiorTime only

946110Grand QuartzTime only

944320King Quartz, LassaleDay, Date

944220-, LassaleDate

944120-, DolceTime only

I have probably missed some of the branding possibilities in the table above, particularly with the 94xx and 96xx calibres. At the dressier, squarer, 80s-er end of things, Seiko seemed to be finding their way with how to use marques like Majesta, Credor, Dolce and Lassale.


The 99 series is probably the easiest to find - they appear in every catalogue from 1978v2 to 1985v1 and must have been made in decent numbers. 9923 King Quartz models are affordable but expect to pay good money for a 9983 Superior. Some calibres must have been produced in very small numbers and are difficult to find - for example, I can't even find a picture of a 9682-engined watch.


Here are my twins...


A 9923-7020 from 1979 (JDM):


A 9923-8010 from 1979 (non-JDM so not "King Quartz"):


A 9723-8000 from 1979 (again, non-JDM):


Come the 1985v2 catalogue, the curtain fell and all the twin quartz models disappear. By this time, Seiko already had other HAQ options - eg the "twin mode" 9063 (1983) and 9531 (1985) calibres which made their way into Credor and Dolce models. The related 9581 calibre resurrected the Grand Seiko branding in 1988.


Today (in fact since 1993) the 9F series stands above all other Seiko Quartz movements. Generally specced at +/-10 seconds per year (exceptionally at +/-5), it's interesting to note that Seiko were getting similar results in 1978.


Additional links...


Information on the 9f series:

A nice article on quartz development and thermocompensation, including Seiko Twin quartz:


October 18, 2016 at 4:19 PM Flag Quote & Reply

Posts: 59

A (dainty) 9642-5000 from 1980 bought from Japan. No King Quartz designation on this one.

December 19, 2016 at 9:11 AM Flag Quote & Reply

Posts: 15

Here's a less common round faced 9983-8020:

The crown looks a bit like Credor which will later feature a lot of Seiko's high end Quartzes:


Rated to incredible 5 SPY!




December 22, 2016 at 10:29 PM Flag Quote & Reply

Posts: 108

@ selfdater:

A very nice summary about Seiko Twin Quartz. Amazing watches; not only the movements are great but also the quality of dial, case and bracelets. It´s a bit confusing that non-JDM-models sometimes are labelled "SQ" but have the "Twin Quartz" writing in the dial or bezel.

Here are my Twin Quartz models; all are non-JDM

9723-8000 (1979)

9923-8010 (1979)

And here are two Twin Quartz which I had some time back.

9726-8000 (1981) with a twotone dial

9923-5000 (1979)

And here is a group photo

February 16, 2017 at 7:50 AM Flag Quote & Reply

Posts: 59

That's a nice set of "Twin Quartz" models there, gufi. I certainly would have kept hold of the 9726 (I don't think you're supposed to get rid of them :) ).

I've picked up a few more since I posted - the favourite is probably this 9256-5010 (JDM, Grand Quartz) from 1978. 10s/year and 110,000 yen in 1979...

April 14, 2017 at 2:38 PM Flag Quote & Reply

Posts: 59

This one has its charms but I'm not certain when it's due to come back into fashion. :) A 9441-5000 from 1980, first seen in the 1981v1 catalogue priced at ¥100,000. 

The stylised "D" at 12 o'clock I take to mean "Dolce"; come the 1982v1 catalogue all the 9441s (Suwa) and 9641s (Daini) were labelled as such. The back reads "TGHA" - which I have been told means "Top Gold Hard Alloy". The case is steel in colour and the crown and bezel are gold (or gold coloured.) It has a sapphire crystal, 19mm lugs and is a very discrete 31mm across. 

May 21, 2017 at 11:24 AM Flag Quote & Reply

James In London
Posts: 13

I have been a big fan of the Twin Quartz since I first discovered it 25 years ago, and like the majority of folks in this thread, fell for the Gerald Genta look of the 9723-8000.


September 19, 2017 at 2:00 PM Flag Quote & Reply

Posts: 59

A 9723-8000 just went for £285 on eBay. That's quite strong in my view; I guess someone wanted to get in with the in-crowd.

September 21, 2017 at 4:09 PM Flag Quote & Reply

Posts: 568

I have had a few Twins in the past and let them go :(    When I found this one I had to have it  :P    A JDM   King Quartz 9723-8040 from June 1979   8)    

January 17, 2018 at 2:54 PM Flag Quote & Reply

Posts: 59

Out with the old, in with the new Don? Lovely dial.

January 26, 2018 at 1:45 PM Flag Quote & Reply

Posts: 568

A JDM Twin Quartz 9943-5000 from Sept. 1978  8)     

March 23, 2018 at 7:35 PM Flag Quote & Reply

Posts: 59

Not gold enough, Don :)

My Gold Cap 9943-8000, also from September 1978:

April 6, 2018 at 9:43 AM Flag Quote & Reply

Posts: 568

From Yahoo Japan is this nice 9923-7020.  My Seiko band.  The watch dated June 1979   8)          

April 19, 2018 at 12:41 AM Flag Quote & Reply

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