Introduced in 2020, the 9SA family of movements are the next generation “Hi-Beat” movement from Grand Seiko. Following on the Seiko 9S8 family of Hi-Beat movements, this family includes numerous improvements, including an 80 hour power reserve. Other advances include a new dual-impulse escapement, the implementation of a free-sprung balance, and a redesigned horizontal gear train.
Specifically, Seiko highlights the following advances in the 9SA series:
- Dual Impulse Escapement – Seiko’s new escapement features a three-pointed anchor similar to the George Daniels/Omega Coaxial or Audemars Piguet three-pallet escapement. This transmits power directly to the balance in one direction and through the pallet fork in the other. These components are manufactured using MEMS technology for extreme precision.
- Free-Sprung Balance – Seiko adopts a free-sprung balance with an overcoil, similar to those used by other high-end watchmakers. The shape is unique to Seiko. The balance wheel also has a new square notched profile with square headed screws for adjustment.
- Horizontal Gear Train – The gear train was redesigned to place all components on the same plane, resulting in a slimmer profile. The movement also adopts a balance bridge design not previously seen in a Seiko calibre.
Seiko 9SA Family
The 9SA family movements operate at 36,000 A/h (10 Hz) yet achieve 80 hours power reserve thanks to precision materials and a novel double-impulse escapement. This escapement, similar to George Daniels famed Coaxial design, is paired with a free-sprung balance, a first for Grand Seiko. The movement wheel train is entirely new as well, designed so all of the gears sit are in a single plane, reducing movement thickness. This is possible thanks to a larger 31.86 mm diameter, up from 28.40 mm in previous Grand Seiko movements.