Realised after eleven years of R&D and comprising 935 parts, the Grande Sonnerie is Greubel Forsey’s most complex creation to date. For their very first Grande Sonnerie, the prestigious watchmaking house founded by Robert Greubel and Stephen Forsey has filed two patents. Dressed in a titanium case it houses an acoustic resonance cage and eleven security functions.

This Grande Sonnerie has powerful acoustics. It is water resistant to 3 atm. It is ergonomically designed for optimum ease of use, while an exceptional repeater power reserve enables it to run for about twenty hours in “Grande Sonnerie” mode. The timepiece is equipped with a silent striking regulator and a Tourbillon 24 Secondes, all housed within the standard dimensions of a Greubel Forsey case.

The most important elements and indications (such as the tourbillon, the cathedral gongs, the striking hammers, and the power reserve and mode indicators) were incorporated with the greatest care to ensure architectural balance. The watch designers succeeded in housing the 935 parts comprising this timepiece and its exterior in a space measuring 43.5 mm in diameter and 16.13 mm high.

The movement is manually wound, but the striking mechanism features a self-winding system which provides about 20 hours of power reserve in Grande Sonnerie mode. The minute repeater and its additional striking mechanism sound the exact time on demand, down to the minute. Beating at 21,600 vibrations per hour, the movement assures a 72-hour chronometric power reserve.

This timepiece has three modes to choose from: Grande Sonnerie (which strikes the hours and the quarters in passing), Petite Sonnerie (which strikes the full hours in passing) and Silence (which does not strike in passing). The pure and rich sound of the Grande Sonnerie is enhanced by an acoustic resonance cage made from titanium. Only five to eight pieces of this timepiece will be realised a year.