What’s difference between Soprod A10 and Seiko 4L25. Soprod A10 reported issues, did Soprod do anything to improve their movement’s quality?

Soprod A10 vs Seiko 4L25

The Soprod A10 and the Seiko 4L25 share the same basic architecture and dimensions. They are both slim (3.6 mm thick) automatic movements with a central rotor, a balance wheel that rotates counter-clockwise, and a date complication at 3 o’clock. They both have 25 jewels, a frequency of 28,800 vph, and a power reserve of about 42 hours. They both use an oscillating pinion for the automatic winding mechanism and have hacking seconds and quick date correction functions.

However, there are also some noticeable differences between them. The most obvious one is the finishing. The Seiko 4L25 has a more refined and elegant appearance, with polished screws, beveled edges, perlage on the bridges, and Geneva stripes on the rotor. The Soprod A10 has a more industrial look, with blued screws, straight edges, circular graining on the bridges, and a plain rotor with an engraved logo. The Seiko 4L25 also has a fine adjustment device for the balance wheel, while the Soprod A10 does not.

Another difference is the escapement. The Seiko 4L25 uses a proprietary Seiko escapement with a Spron 510 mainspring and a Spron 610 balance spring. These are special alloys developed by Seiko that have high resistance to magnetism, temperature changes, and shock. The Soprod A10 uses a Swiss-made escapement from Festina’s own subsidiary mhvj, with a Nivaflex NM mainspring and an Anachron balance spring. These are also high-quality materials, but they are not exclusive to Soprod.

A third difference is the certification. The Seiko 4L25 is not officially certified by any external agency, but it is adjusted in six positions and tested for accuracy by Seiko’s own standards. The Soprod A10 can be certified by COSC (the Swiss Official Chronometer Testing Institute) upon request, but this is not mandatory or common.

Modifications by Soprod

Soprod did not just copy the Seiko 4L25 design, but made some modifications to suit their own preferences and market needs. Some of these modifications are:

– Changing the shock absorber system from Seiko’s Diashock to Incabloc’s Double-Cone.

– Changing the balance wheel material from Glucydur to Glucydur G.

– Changing the rotor bearing from ball bearing to jewel bearing.

– Changing the date wheel font and color.

– Adding various options for dial feet positions, hand sizes, and date window shapes.

– Offering different versions of the movement with open balance wheel or skeletonized dial.

– Offering different modules for complications such as chronograph, moon phase, power reserve indicator, etc.

Issues with Soprod A10

Despite being a well-designed and well-made movement, the Soprod A10 is not without its flaws. Some of the issues that have been reported by users and watchmakers are:

– Poor accuracy or erratic timekeeping.

– Rotor noise or wobble.

– Date change malfunction or misalignment.

– Movement stoppage or failure.

Causes of Soprod A10 issues

It is hard to pinpoint the exact causes of these issues without examining each case individually, but some possible factors are:

– Quality control or assembly errors by Soprod or their subcontractors.

– Damage or wear during transportation or storage.

– Improper handling or servicing by watchmakers or owners.

– Environmental factors such as magnetism, moisture, dust, shock, etc.

Solutions by Soprod

Soprod has not publicly acknowledged or addressed these issues in an official way, but they have made some improvements to their movement over time. Some of these improvements are:

– Redesigning the movement and renaming it as A10-2 in 2012.

– Changing the escapement supplier from Seiko to mhvj in 2012.

– Renaming the movement as M100 in 2016 and refreshing the modular offerings. (The M100 is an improved version of the A10, with different quality levels, finishing options, and versions. The M100 is also considered to be a high-end movement with advanced features, while the A10 is a mass-produced movement.

I could not find any reports of problems with the M100 on the web.)

– Offering COSC certification on request.


The Soprod A10 is a Swiss alternative to the ETA 2892A2 that is based on the Seiko 4L25 design. It has some advantages and disadvantages compared to its Japanese and Swiss counterparts, and it has some issues that need to be addressed. However, it is still a reliable and versatile movement that can power many high-end watches with different complications. If you are interested in buying a watch with a Soprod A10 movement, you should do your research and check the reviews and feedback from other users. You should also make sure that the watch is serviced by a qualified and experienced watchmaker who knows how to handle this movement.

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