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 the Greubel Forsey Grande Sonnerie timepiece will be realised a year.
Technical details
Model: Greubel Forsey Grande Sonnerie
In titanium – Millésimé
Movement
Special features
Patented hand-wound movement and striking-mechanism
Full striking-mechanism with automatic winding
Petite and Grande Sonnerie timepiece
Minute repeater on demand by crown mounted pusher
Striking modes selection by pusher
Grande and petite sonnerie, silence
Striking power reserve
Tourbillon 24 Secondes
Hours and minutes
Small seconds
Movement power reserve display
Movement dimensions
• Diameter: 36.40 mm
• Thickness: 11.13 mm
Number of parts
• Timepiece: 935 parts
• Movement: 855 parts
• Cage tourbillon: 86 parts
• Weight of the cage: 0.37 g
Number of jewels
• 85
• Olived-domed jewels in gold chatons
Chronometric power reserve
• 72 hours
Barrels
• Two coaxial series-coupled fast-rotating barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension
Balance wheel
• Variable-inertia with gold mean-time screws (10 mm diameter)
Frequency
• 21’600 vibrations/hour
Balance spring
• Phillips terminal curve
• Geneva-style stud
Main plates
• Nickel silver, spotted, with polished beveling and countersinks, straight-grained flanks, nickel-palladium treatment
Bridges
• Nickel silver, frosted and spotted, with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
• Flat black polished steel tourbillon bridge, with polished bevelling and countersinks, straight-grained flanks
Tourbillon
• Inclined at a 25° angle, 24-seconds rotation
• Light alloy cage pillars
• Titanium cage bridges
• Gold counterweight
Gearing
• Involute circle profile
• Tangential inclined gear on fixed wheel and profiled teeth on escape wheel pinion
Movement and striking-mechanism displays
Hours and minutes
Small seconds on a sector
72-hours power reserve on a sector
Striking power reserve on a sector
Three striking modes:
– GS (Grande Sonnerie) strikes the hours and quarters in passing
– PS (Petite Sonnerie) strikes the full hours in passing
– SL (Silence) does not strike in passing
Striking-mechanism
Acoustic
• One-piece cathedral gongs on three levels, two notes, visible through the tourbillon’s lateral window, flat black polished steel gongs block, with polished bevelling and countersinks
• Two flat black polished steel visible hammers, with polished bevelling and countersinks
• Flat black polished hammers bridge, with a raised polished engraving, with polished beveling and countersinks, straight-grained flanks
• Silent speed regulating governor
• Dedicated striking barrel maximising hammer force and striking power reserve (about 20 hours in Grande Sonnerie mode)
• Striking rhythm optimised without pause
Mechanism
• Visible on movement side, straight-grained or circular-grained steel, with polished beveling and countersinks, straight-grained flanks
• Protected with eleven securities, for example when striking is in progress, when time setting, when the dedicated striking barrel is wound down…
• Minute repeater striking hours – quarters – minutes, down to the minute
Automatic winding (only for striking-mechanism)
• Oscillating weight in platinum with relief-engraved texts, flat black polished, with polished bevelling, straight-grained flanks
• Flat black polished gold central plate with relief- engraved “GF” logo, polished beveling and countersinks, straight-grained flanks
• Gold peripheral plate, circular-grained, engraved and lacquered “Grande Sonnerie” with polished bevelling and countersinks
• Flat black polished gold decorative plate with relief-engraved text, with polished beveling and countersinks, straight-grained flanks, with a screwed gold chaton
Exterior
Case
In titanium with asymmetrical convex synthetic sapphire crystal
Transparent back with asymmetrical convex synthetic sapphire crystal
Lateral window with shaped synthetic sapphire crystal
Three-dimensional, variable geometry-shaped lugs
Raised polished engraving “Grande Sonnerie” and “Greubel Forsey” on a hand-punched background
Gold security screws
Hand-polished bezel, caseband and caseback
White gold modes selection pusher, with a raised engraving on a hand-punched background
Hand-engraved individual number
Case diameter: 43.50 mm
Height: 16.13 mm
Water resistance: 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown with pusher: In white gold with engraved GF logo
Dial
Multi-level in gold, black colour
Window showing the hammers and the gongs
Gold hour markers
Gold display sectors
Gold GF logo
Hands
Hours and minutes in gold with Super-LumiNova, small seconds and power reserve in polished gold
Striking modes and striking power reserve in polished gold
Strap and clasp
Hand-sewn alligator
Titanium folding clasp, engraved with the GF logo
