Stephen Forsey, co-founder of the Greubel-Forsey watches in a chat with Hiren Kumar Bose on the Grande Sonnerie which is one of the contenders for the best in ‘mechanical expression’ title of GPHG 2018
With Hours, Minutes, Small Second, Power reserve, Striking power reserve, Grande Sonnerie, Petite Sonnerie, Minute repeater on demand, and Tourbillon 24 Secondes packed in a 43.5 mm case. That itself says why it took 11 years of R&D to make this. Do you consider it the pinnacle of watchmaking at Greubel Forsey and an achievement in horology in general?
Quite simply, the Greubel Forsey Grande Sonnerie deliberately redefines the striking wristwatch for the 21st century. To do this we had to study and research every single aspect, such as attaining extended strike mechanism power reserve, imagining and constructing a completely new striking mechanism including no fewer than 11 security mechanisms for a previously unseen level of comfort and peace of mind for the collector. Combining and integrating the 935 components into an existing and very comfortable 43.5 mm x 16.13mm case. Over three years of dynamic on the wrist testing and refinements were part of our R&D which included a number of subprojects, like for example (but not exhaustive) achieving a strong and pleasant sound for the acoustics with 30m water resistance. This by itself required some four years of work in our laboratory.
I’m told Greubel-Forsey has filed two patents too. What are they for?
There are indeed two patents, one of which is for our unique 24 seconds Tourbillon and another one in the striking mechanism. The Grand Sonnerie is such a concentration of many innovative elements built upon our years of experience in striking mechanisms that there are many innovative factors which combine together to make this Grande Sonnerie such a groundbreaking timepiece.
Do take us through the astounding acoustics of the Grande Sonnerie?
Our many years of experience with antique and modern striking and repeating watches was, of course, fundamental in ensuring the creation of this unique Grande Sonnerie because you can only finally appreciate the acoustic result when the timepiece is finally complete! We, therefore, knew how to make a particularly detailed study of the essential areas such as the acoustics, hammers, gongs and striking mechanism. The titanium case enabled us to create a unique acoustic resonating cage, which like a stringed instrument, provides the loudest possible volume and the pure chime is remarkable, particularly when combined with the 30m water resistance. The extremely pure crystalline strike is also ensured thanks to the one-piece double cathedral gongs which are on three levels with respectively sounding high and low notes. The silent speed regulating governor also does away with any inelegant background noise from the striking mechanism. This timepiece has three striking modes: 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). There is also a minute repeating function operated by the pusher on the winding crown which can be used in any of the 3 striking modes.
This timepiece takes watchmaking to another level with it’s a silent speed regulating governor, unlike the traditional strike speed regulation mechanisms. Comment.
This silent striking speed regulation is part of the unique and innovative construction. It incorporates an innovative inertia flywheel which we have specially designed to eliminate the buzzing tic-tac sound habitually made by traditional strike speed regulation mechanisms which use a simplified escapement.