Spring Drive Cal. 9RA5
Grand Seiko’s Famed Hybrid Movement Just Got a Significant Upgrade
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Grand Seiko’s Spring Drive movement is unique in watchmaking — a type of hybrid caliber, it combines a mechanical watch’s mainspring with a special speed control mechanism incorporating an integrated circuit, and electronic brake and a quartz crystal. The result is a movement that combines the best of mechanical watchmaking with the accuracy of battery-powered watches. (At the 1999 debut of the original Spring Drive, the movement was accurate to one second per day.)
But over 20 years have passed since then, and Grand Seiko has improved its signature technology by leaps and bounds. The new Caliber 9RA5 features a 5-day power reserve, an accuracy of ±10 seconds per month, and a thickness of just 5mm. Improved rigidity and shock resistance means a movement that even meets ISO standards for dive watches, and a new sensor helps compensate for inaccuracies resulting from temperature fluctuations.
The hybrid nature of the new 9RA5 is evident in the smooth glide of the sweep seconds hand, a dead giveaway that the watch in question isn’t a simple battery-powered quartz watch. Finished to a high degree that’s reflective of Grand Seiko’s emphasis on craftsmanship, the new movement is debuting in a dive watch, the Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M, which features a helium scape valve; a 46.9mm high-intensity titanium case that’s 40% lighter than steal; and, of course, 600m of water resistance. A power reserve indicator at 10 o’clock is divided into 10 sections to give a highly accurate picture of remaining power, and the watch is designed for easy disassembly and servicing.
The new Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M is a limited edition of 700 pieces and ships with a special Grand Seiko 60th anniversary box and a blue silicon strap — it’ll be available worldwide in August with a price of $11,100.
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