Creating a Grande Sonnerie is not for the feeble minded. This is an undertaking which sits within the holiest of the holy within the ranks of complicated watchmaking. The ultimate complication. The big Kahuna. The Grande Sonnerie. Greubel Forsey, famed for their inclined tourbillons now join these rarefied ranks, and announces their own Grande Sonnerie.
The Greubel Forsey Grande Sonnerie will be made in a small series of 3-5 watches a year. Shown here is the launch version in titanium case and black dial.
With two patents filed, the development of the Grande Sonnerie has taken Greubel Forsey some eleven years of research and development. Needless to say, the watch is extremely complicated. No fewer than 935 parts, two patents and the development of an acoustic resonance cage incorporating eleven security functions. This is indeed a monumental watch.
The dial side of the Greubel Forsey Grande Sonnerie shows all the indications with clarity.
Since the beginning of their partnership, Robert Greubel and Stephen Forsey have been thinking of their own cotemporary intepretation of the summit of the complication: the Grande Sonnerie. The watch promises to represent the quintessence of their expertise and ideal of watchmaking.
The watch is loosely based on their Tourbillon 24 Seconds, and housed in a standard Greubel Forsey case, with the characteristic protutions for the tourbillon assembly.
The rear features Greubel Forsey’s famed miniature writing expressing a special message to be discovered by the owner.
The important elements and indications such s the tourbillon, the cathedral gongs, the striking hammers, and the power reserve and mode indicators are incorporated into the architecture of the dial and design. All 935 components are housed in a case measuring 43.5mm in diameter and 15.13mm high.
The Greubel Forsey Grance Donnerie in Titanium, showing both the dial side and the case back.
The Grande Sonnerie is well and truly Greubel Forsey’s most complex creation to date. 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 sounds the exact time on demand, down to the minute. The specific characteristics of this timepiece include, in particular: 21,600 vibrations/hour and 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.
The GF movement.
Five to eight pieces of this timepiece will be realised a year. We look forward to photographing this watch in Geneva during the SIHH next week, and bring you our detailed review with our usual analysis.
The Greubel Forsey Grande Sonnerie is priced at CHF 1,150,000 before taxes, the buyer should not be of faint heart either.
Greubel Forsey Grande Sonnerie Full Technical Specs
In titanium – Millésimé
Hand-wound movement with patented tourbillon • Patents pending
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
Movement
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 bevelling
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, straightgrained
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
• 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 power reserve on a sector
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 bevelling
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 bevelling
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 bevelling
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 bevelling
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 dimensions
• Diameter: 43.50 mm
• Thickness: 16.13 mm
Water resistance of the case
• Water-resistant 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
