In 1998, the 9S mechanical caliber opened a new chapter in the Grand Seiko story. Today, the launch of a new high beat mechanical caliber, 9SA5 represents an advance just as important as the first 9S. It is, beyond doubt, the finest mechanical caliber that Grand Seiko has ever created. A watch offered in a limited edition of 100 will be the first to be powered by this new caliber.
The challenge for any watchmaker who creates a high beat movement is to strike the perfect balance between precision, power and size without compromising on any of these parameters. In developing the 9SA5 caliber, the Grand Seiko development team set out to deliver the same level of stable accuracy as that of their existing 36,000 vph movement but to deliver a longer power reserve. They succeeded in characteristically uncompromising style. Caliber 9SA5 has a precision rate of +5 to –3 seconds a day and a power reserve of 80 hours.
The precision, power and slimness of Caliber 9SA5 are the result of the radical re-design of three key structures and some components within them for which several patents are either already granted or pending.
1. Dual Impulse Escapement
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.
Dual Impulse Escapement © Grand Seiko
2. Grand Seiko Free-sprung Balance
9SA5 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.
Grand Seiko Free-sprung Balance © Grand Seiko
3. Horizontal Gear Train
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.
The movement is as beautifully finished as it is efficient. The bridge has a gently curving outline that is inspired by the shapes of Mt. Iwate and a bend in the Shizukuishi River that runs near the studio where the watch is made.
Caliber 9SA5 © Grand Seiko
Just as Caliber 9SA5 makes a significant and defining statement about the next stage of Grand Seiko’s technical development, the design also has a distinctive look that marks a new beginning. The watch remains true to the Grand Seiko Style that was defined back in 1967 with the celebrated 44GS but it is subtly different in ways that are much more than cosmetic. This new design has all the hallmarks of Grand Seiko but also offers enhanced comfort and legibility.
Grand Seiko 60th Anniversary Limited Edition, Réf. SLGH002 © Grand Seiko
This 18k-yellow gold watch will be available at the Grand Seiko Boutiques in August 2020.
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