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Soprod Newton

Last Update: July 30, 2020

Introduced in 2020, the Soprod “Newton” is an inexpensive Swiss movement designed for mass production. It is a modern movement and does not appear to be related to the earlier Soprod A10 family, which was based on a Seiko design. Key elements include a full balance bridge supporting the exposed balance at 6:00, suggesting that an open heart version is also in the works.

The initial Newton model features a date-only calendar

The Newton movement measures 11.5 ligne (25.60 mm) in diameter and is not especially thin, even for a central-rotor automatic, at 4.60 mm. It includes a date-only calendar with semi-instantaneous changes and quick adjustment using the crown, a stop-seconds device, and fast 28,800 A/h (4 Hz) operation. It has 23 jewels and is rated for 44 hours power reserve.

The Newton by Soprod is offered in two quality versions:

“Sophisticated” – Plus or minus 7 seconds per day, adjusted in 3 positions
“Top-Flight” – Plus or minus 4 seconds per day, adjusted in 5 positions

Each movement is tested by Dubois Laboratory and earns a “Chronofiable Certificate” after a number of tests.

The initial Soprod Newton movement, identified as “P092” on the plate, is presumably the first in a family of related movements from Soprod.

The Newton design is quite different from the Soprod A10 or M100 movement

Soprod’s previous offering was an ultra-thin automatic based on the Seiko 4L25 design. Introduced in 2004, the Alternance 10 (later called A10 or M100) was a high-end movement with advanced features and a radically different design more competitive with the ETA 2892A2. In contrast, the Newton is thicker and more plain in design. Notable differences, apart from the use of a full balance bridge, include the location of most components below plates and bridges on the top and a single-screw rotor with five ball bearings (unlike the triple-screw, 7-ball A10). This places it in competition with the common ETA 2824-2 (and similar Sellita SW200-1) in mainstream watches. But the Newton is quite different in design from this movement as well, with a smaller balance on the opposite side and the bridge.

Soprod Newton Family

Last Update: July 30, 2020

Introduced in 2020, the Soprod “Newton” is an inexpensive Swiss movement designed for mass production. It is a modern movement and does not appear to be related to the earlier Soprod A10 family, which was based on a Seiko design. Key elements include a full balance bridge supporting the exposed balance at 6:00, a robust design with plates over most gears, and a central winding rotor supported by five ball bearings and a single screw.

The Newton design is quite different from the Soprod A10 or M100 movement

Seiko 7S Family

Last Update: June 12, 2019

The Seiko 7S family was a widely-produced automatic watch movement produced from 1996 to the present. The NH family is also produced by Seiko Instruments (SII) but sold by Time Module (TMI) to third-party watch makers. The 7S family was the basis for the following 4R and 6R families.

The Seiko 7S was developed for reliability, economy, and ease of maintenance. It features a simplified design to reduce component count and cost, and some components are made of plastic to reduce the need for lubrication. Although it lacks hacking and hand-winding, it has bi-directional automatic winding thanks to the Seiko Magic Lever system. It oscillates at 21,600 A/h and returns respectable accuracy, though Seiko did not often specify the exact number. 7S movements were available in both 21- and 23-jewel versions, were revised many times (resulting in “A”, “B”, and even “C” variants), and were produced in factories in Singapore, Malaysia, and Japan.

The “B” series movements, introduced in October 2006, feature a new balance staff with open-ended stud carriers. The “C” series of about 2011 was more substantially revised, with over a dozen parts changes incompatible with previous movements.

The date-only 7S25 (and similar 7S35 and 7S55) are considerably rarer than the day-date 7S26 (and similar 7S36). Some date-only or time-only watches in fact use the day-date movement because it is so much more common, and the entire family is sometimes referred to as “7S26” due to its ubiquity.

TMI produced 7S movements as the NH25 and NH26 for third-party watch manufacturers. These were based on the updated 21-jewel 7S25B and 7S26B.

SII Cal. NH25 is the OEM equivalent of Seiko Cal. 7S25

	21 Jewel	23 Jewel
Date Only	7S25A 7S25B 7S25C NH25A	7S35A 7S35B 7S35C 7S55A 7S55B
Day-Date	7S26A 7S26B 7S26C NH26A	7S36A 7S36B 7S36C

Miyota 8215

Last Update: June 6, 2019

Part of the Miyota Cal. 8200 family, Cal. 8215 was introduced in 1977 and remains in production as of 2020. Cal. 821A is substantially similar but better finished, with ribbing on the reverse side and a slotted rotor. A gilt version of each is also available.

All members of the Miyota 8200 family have indirect seconds, which causes a noticeable wobble to the central seconds hand. When struck, the seconds hand can appear to pause for up to 2 seconds due to slack in the movement.

Similar date-only movements in the Miyota 8200 family include Cal. 8210, 8210A, 821A, 8215A, and the hand-winding 8260 and 8260A.

Cal. 8215 is used by SevenFriday. Cal. 821A is used by Laco.

Sea-Gull’s Cal. ST1612 is similar in design to the Miyota 8215.

	Date at 3:00	Date at 6:00

Black on White Date Wheel	8215-21A 821A-43D 821A-43A	8215-1TH 821A-43Z
White on Black Date Wheel	8215-1AV	821A-43K