Seiko caliber 9SA5
Self-winding movement with Dual Impulse Escapement.
Diameter: 31.6mm, Thickness: 5.18mm
Instant date change
The escapement is entirely new and was developed in-house. It enables the escapement wheel to transmit power directly to the balance, leading to an efficiency increase. It is unique in that, in one direction, power is transmitted directly to the balance while in the other it is via the pallet fork, as in a traditional escapement. Both pallet fork and escapement wheel are made using MEMS technology.
The 9SA5 furthermore uses a new and special free-sprung balance developed for this caliber. It retains its precision for longer and is more resistant to shock and friction. While the current Caliber 9S uses a flat hairspring, 9SA5 uses an overcoil, whose curve shape was decided after more than 80,000 simulations with the result that its performance is optimized in every possible position. The uniqueness is that it can improve the isochronism. The secret lies in the precision manufacture of the components as well as the extraordinary adjustment skills of the watchmakers at the Grand Seiko Studio Shizukuishi.
The new caliber is 15% slimmer than the current Grand Seiko high beat caliber, thanks to the innovative horizontal layout of the barrel and gear trains.
In addition to these three new components, Caliber 9SA5 has other features that contribute to its extraordinary performance. Two barrels, arranged in sequence, enhance the power reserve, the date change is virtually instantaneous and the positioning of the winding stem close to the rotor allows the watch to sit closer to the wrist.