So at Baselworld 2018, Seiko introduced a new Presage model. The international model name is SJE073J1. There was a fair bit of fanfare to this model because of the “new” caliber 6L35 that powers it. It promises to be slimmer (3.7mm), running at a higher 28,800 bph and has a fairly large power reserve at 50 hours. This is in comparison to the 6R15 movement that it’s kind of replacing, which runs at 21,600 bph, has a power reserve at 50 hours but is fairly thick at 5.3mm.

The new 6L35 is also factory adjusted to +15 sec / -10 sec a day versus the +25/-15 sec a day of the 6R15.

All in, this seems like a great move by Seiko, except that the Presage is now JPY 240,000 or USD 2,200!

You can see the official Japanese website Basel 2018 announcement here and the English press release here.

I’m fine with all these except for 1 thing, this is not a completely new caliber from Seiko Japan. In fact, it was first introduced way back in 2007 as the 4L25 and was finally discontinued in 2013 as the 4L75, before being resurrected in 2018 here as the 6L35.

The 4L25 and 4L75 movements are hi-beat movements, beating at 28,800 bph and had a power reserve of 42 hours and 50 hours respectively. However both 4L movements only had 25 jewels, 1 less than the 6L35. At the point of introduction, they were one of Seiko’s slimmest automatic movements at 3.6mm thick and measured 25.6mm across. These measurements were by the way also shared by the ETA 2892 and this was no coincidence as Seiko meant for the 4L caliber to be a drop-in replacement for the 2892.

Other than having the same dimensions and movement specifications, Seiko also took the liberty to utilise several Swiss designs in the movement architecture, thus moving away from several design quirks that would have identified it as a Seiko movement. For example, the 4L utilised the reverser wheel design rather than Seiko’s magic lever to wind the mainspring, and also adopted the Incabloc anti-shock suystem rather than its own Diafix antishock system. As others before me have speculated, perhaps this was all done in the hope of attracting Swiss customers.

Also it’ll be interesting to note that even Seiko’s highest end movement in the Grand Seiko 9S (9S6X and beyond, as the 9S5X uses the magic lever) uses the reverser wheel design and not Seiko’s magic lever system.

Not surprising, Seiko did succeed to some extent in this as it was thought that Soprod eventually licensed this design from Seiko and produced the Soprod A-10 caliber from this base caliber. Note that neither company have ever acknowledge who really designed the movement and who licensed it.

The 4L25 movement was introduced by Seiko in 2007 in the SARA 001/3/7/9/11/13 models. At that time, the models were incredibly expensive at JPY 189,000 and did not sell well. They were discontinued in 2008.

The 4L75 movements were introduced by Seiko under the Credor lineage under the GCBW 993/5/7/9 and sold for JPY 260,000 between 2007 and 2013. (Side note: Compare the price of the Presage now against the Credor prices then).

How did I come to the conclusion that the new 6L35 was derived from the old 4L25/75 movements?

The JDM model number of the Presage is SARA015. This was the first important clue that I got. The previous SARA series that was discontinued in 2008 ended with the model number SARA013. Hence it made sense for the new model using the same movement to be numbered in order (i.e. 15 follows from 13. Seiko do not usually use even numbers in its naming system except for special models). This cannot be told from the international model number which was SJE073J1. I have to give credit to akable at plus9time for this fact, as he was the only blogger I’ve seen so far to quote the JDM model number alongside its international model number. Once I’ve gotten the JDM number, I could then compare the dimensions of the old 4L vs the new 6L. The thickness, diameter, power reserve, beat rates were all a match! I then compared pictures of the new 6L35 versus the 4L25 movements. It was oddly difficult to find ANY real life picture of the 6L35 on the Internet and I had to rely on the press image.

The green boxes illustrate what are the smoking guns that they are the same movement.

a) The fine adjuster design looks to be unchanged.

b) The same 3 screw design on the rotor remains unchanged.

c) The slightly oval shaped cut out where the balance bridge meets the main bridge remains unchanged.

The red boxes highlights where the important differences are

i) The balance wheel has a different design now. Previously, the 4L had a smooth balance wheel, while the 6L now has studs on the circumference

(Edited: There is no difference in the balance wheel used. 6L is still using the smooth balance wheel, but now the studs are gold, compared to the silver studs used in the 4L)

ii) More importantly, the anti-shock system is now conformed to Seiko’s flower-shaped antishock, and no longer uses the Incabloc antishock. This also brings it in line with the so-called higher end Seikos (i.e. 9S/9R/8L/4S), which uses the flower shaped anti-shock versus the tadpole/rectangular shaped anti-shock used in the lower end Seikos (i.e. 7S/4R/6R/8R).

The 6L35 appears to be a mix of the 4L25 and 4L75 as it has the power reserve of the 4L25 (45 hours), but the accuracy of the 4L75 (+15/-10 sec) rather than the 4L25 which was slightly less well adjusted. This helps to explain the rather high pricing of this Presage which really is more in line with the pricing of the Credors powered previously by the 4L75.

Why then did Seiko make an imperfect clone of the 4L given that all the fundamental specifications of the movement are the same? I suspect that this was due to the licencing arrangement between Soprod and Seiko regarding the 4L and Seiko had to work around this by changing, cosmetically, certain parts of the 6L including the balance wheel and anti-shock system in order to avoid infringing their agreement with Soprod.

This then brings us to the next question of why Seiko had to bring back the 4L caliber to power its new Presage models.

Firstly, as many people have correctly noted, Seiko movements are generally never thin. For example, all modern GS are at least 13mm thick. Having the 3.6mm thick 6L movement would allow Seiko to introduce true thin dress watches below 10mm and better compete with its European counterparts.

Secondly and more importantly, Seiko likely made a huge expense in designing and manufacturing the 4L family, and it was only used in models from 2007 – 2008, with it then being relegated to the Credors until 2013. Seiko probably had to recoup the capital it invested in building the machines to manufacture the 4L family, and was waiting for the right opportunity to utilise the 4L movements in watches that could fetch a higher price. After all, it’s pretty telling that the 4L/6L is the first ever movement that went from an upper tier line (Credor) to a lower tier line (Presage). Every other movement generally stayed within its own price bucket/line, with the exception of the Seiko 4S, which moved upward to power the Credor from its pedestrian origins powering the normal Seiko mechanical timepieces.

The time is now right for Seiko to introduce ever higher priced watches that do not carry the GS designation which requires manpower intensive work in adjusting and then certifying each and every watch. By introducing the 6L powered Presage (probably the most expensive time only Presage ever), Seiko could hope to recover some of the investment made in its movement, while getting consumers used to ever higher price points in the Presage range. This would then allow Seiko to creep the price points of its top tier Credor and Grand Seiko lines upwards as well.

(Side Note @ 4 April 2018: It was brought to my attention below by akable that if the 6L was really a close clone of the 4L, then it will no longer qualify for the “Trimatic” branding that Seiko had associated with the Presage line as it will no longer be using the magic lever winding system.

The “Trimatic” line refers to the usage of Seiko’s magic lever winding mechanism, Diashock anti-shock system and proprietary SPRON alloy used to manufacture the mainspring and balance spring. See here for an explanation.

I went to the Seiko Japan Presage website today and I did not find any mention of the “Trimatic” term any longer. Perhaps it is no longer in use.

We will know for sure if the 6L is indeed “Trimatic” once real life photos of the movement surface.)

Resources

https://www.watch-wiki.net/index.php?title=Seiko_4L25

https://www.watch-wiki.net/index.php?title=Soprod_A-10

https://www.plus9time.com/blog/2018/3/22/baselworld-2018-seiko-presage

https://www.seikowatches.com/au-en/products/presage/special/sje073j1/

https://www.seiko-watch.co.jp/news/baselworld/posts/791/20180322

http://forums.timezone.com/index.php?t=tree&goto=1993179&rid=0

http://swanson.jp/X/tsSEIKO/SKOSARA.html

http://housekihiroba.jp/shop/g/g454342001/