Before the creation of Spring Drive, the choice was stark. Either you chose a mechanical watch and enjoyed its traditional character and autonomy but tolerated its relative imprecision or you wore an electronic watch that was up to ten times more accurate but required a battery. In 1999, Spring Drive resolved this dilemma by combining the best of both the existing two watch technologies in a watch powered by a mainspring that offered accuracy of one second a day. Spring Drive was then, and remains today, one of horology’s greatest advances.Now, two decades on, Grand Seiko introduces a new generation Spring Drive caliber that is slimmer, even more precise and has a greater power reserve. Caliber 9RA5 takes Spring Drive technology to a new level of excellence and opens a new era in the history of Grand Seiko.
The goal was ambitious. The Grand Seiko team aimed to create a Spring Drive watch that, in size, performance and functionality, would set a new standard for any spring-powered watch. Their creation, Caliber 9RA5, does precisely that. In comparison to the 9R6 caliber that is the mainstay of the current collection, Caliber 9RA5 delivers a five-day power reserve, an increase of 60%. Its monthly precision rate has risen from ±15 seconds a month to ±10. The movement depth has been reduced from 5.8mm to 5.0mm and the speed of the date change has been greatly increased.