Girard Perregaux

AndrewD
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Improving the sound of the 1966 Minute Repeater

Girard-Perregaux invested an enormous amount of effort into obtaining the best volume and quality of sound from their Repeater. Classically gold has not been considered the optimum material for sound propagation. Some repeater designs use the superior sound conduction properties of steel and others have exploited the front crystal as a vibrating surface. The engineers at GP have optimised the sound from the 1966 Minute Repeater in three ways:

*  The gold case is relatively thin which is apparent from the lightness of the watch, despite its proportions.

*  The internal case volume has been maximised by using a rear convex sapphire so there is a larger amount of vibrating air.

*  And finally, the inner surface of the case back has been diamond polished to reduce acoustic interference.

Normally the outside of the case is polished with a diamond to produce a perfectly smooth and beautiful finish but this diamond polishing process has been applied to the inner surface of the 1966 Repeater as well. This is not something that is visible from the outside as you look into the movement, but it has the effect of improving the propagation of the sound. The same effect is used inside a brass musical instrument such as a trumpet or saxophone. All the surfaces are polished to allow the sound to run smoothly without perturbation.

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