A Closer Look at the Greubel Forsey Grande SonnerieBy Cheryl Chia
In a time when watchmaking, in broad strokes, is characterized by an ever-increasing dependence on technology and automation, and when many complications — including perpetual calendars, tourbillons and rattrapantes — have been successfully realized on large production scales, creating a grande sonnerie still remains an atavistic ritual. As with minute repeaters, their immutable intricacy in construction, assembly and adjustment defies the remotest attempt at industrialization, requiring both a dexterous hand and a keen ear.
So much so that the number of watchmakers — as individuals or as brands — capable of building a grande sonnerie on their own, can still be counted on two hands since Philippe Dufour presented the first Grande Sonnerie wristwatch in 1992. The list includes Jaeger-LeCoultre, Patek Philippe, Audemars Piguet, Franck Muller and F.P. Journe.
In 2017, Greubel Forsey entered the fold with what was the most tremendous addition to its already highly impressive canon — the Grande Sonnerie with a 24-seconds inclined tourbillon. Having met at Renaud & Papi (now Audemars Piguet Renaud & Papi), one of the industry’s top repeater makers, Robert Greubel and Stephen Forsey’s desire to create a chiming watch had always loomed large in the background. It took them 11 years of expert labor to bring the watch to completion and, in true Greubel Forsey fashion, make decisive improvements to the complication. That is further combined with the brand’s obsessive approach to finishing, making the Grande Sonnerie the finest of its ilk currently in production.
A grande sonnerie is sometimes referred to as a clockwatch because, as with a mantel clock, it chimes the time — the hours and quarters — in passing or, in other words, automatically without having to be activated by the wearer. Because of its regular chiming, it demands a great deal of energy, hence necessitating a dedicated mainspring barrel. Almost invariably, the strike train in such watches can be set to either one of three modes: grande sonnerie; petit sonnerie, which only strikes the hours in passing; or silence.
In contrast, a minute repeater only chimes the time — hours, quarters and minutes — on demand. As such, the tension required to sound the gongs each time is not nearly as great as that for a grande sonnerie, so all it typically requires is a small secondary spring that is charged when a spring-loaded slider is pulled, or a pusher is depressed. Once released, energy is then discharged to power the strike train. By design, grande sonnerie wristwatches are often also minute repeaters, enabling time to be struck on demand as well as in passing.
On the dial of the Greubel Forsey Grande Sonnerie, there is a small 72-hour power-reserve indicator for the timekeeping mainsprings at five o’clock, and a dedicated 20-hour power-reserve display at two o’clock for the grande sonnerie. A subdial at three o’clock indicates the sonnerie modes, which are adjusted via the selector pusher at four o’clock on the case. Visible through an aperture between 10 and 11 o’clock are the hammers and gongs of the chiming mechanism.
Beyond the acoustics, the watch also incorporates the brand’s landmark complication — a fast-rotating, 25° inclined tourbillon — between seven and eight o’clock. The basis for an inclined tourbillon in a wristwatch is to ensure that the regulator is never in the most extreme — entirely vertical or entirely horizontal — positions, avoiding the full downward pull of gravity and resulting in less variation in rate. This is further bolstered by its high-speed cage, which completes a full rotation once every 24 seconds as opposed to the standard 60 seconds. To reduce load on the going train, the cage has been fashioned from titanium.
Notably, a simpler variation of the movement was designed for the Vacheron Constantin Les Cabinotiers Symphonia Grande Sonnerie 1860 launched that same year. Thus both watches have a similar architecture where the components are contained on three plates with the bulk of the chiming mechanism located on the backplate instead of the dial side. As such, in contrast to most chiming watches where only the hammers and gongs are visible on the backplate, the chiming mechanism is partially visible on the back of the watch with the barrels located on the second plate.
All mainsprings are wound using the crown. Turning it clockwise winds a pair of stacked co-axially mounted mainspring barrels for timekeeping, and turning it counterclockwise winds the sonnerie barrel. Additionally, the sonnerie also has an automatic winding mechanism by means of a platinum oscillating weight visible at the back of the watch.
Also visible on the reverse is a pair of cams pivotably mounted on the central axis of the movement — a quarter snail with four steps and minute snail with four arms, each with 15 steps — that are responsible for translating the movement of the hands to sound. As the center wheel rotates once per hour, it governs the rotation of the minute and quarter snail. The quarter snail has a pin that advances the tooth of a 12-hour star, which is fixed to an hour snail. Each of these snail cams is sampled by a lever of a complex shape with a feeler tip and both internal as well as external toothing. Each lever lifts a pallet that in turn actuates the hammers.
However, Greubel Forsey’s key innovation lies in eliminating the silent interval that typically occurs between the striking of the hours and that of the quarters, or between that of the hours and that of the minutes when there is no quarter to be struck. Due to the position and shape of the racks, the time taken for the pin of the hour rack to come into contact with the opening of the quarter rack varies.
To eliminate this dead time, the shape of the racks has been revised, and additional toothing has been added on the inner part of the quarter rack. The hour and quarter racks are now directly connected by means of a driving hook articulated on the hour rack that picks up the internal tooth on the quarter rack. This makes it possible to regularize the intervals.
The speed at which the gongs are struck is controlled by a gear train driven by the sonnerie barrel. Along this gear train is a flywheel governor that reduces the unwinding rate of the mainspring by means of providing inertial resistance, thus setting the tempo of the chimes. In contrast to an anchor governor which makes a distinctive buzzing noise, the flywheel governor is almost inaudible. Also visible on the back of the watch is a spiral spring that is charged when the minute repeater is armed via a pusher on the crown.
The entire movement is surrounded by a pair of cathedral gongs made of hardened steel, with each encircling the shaped movement almost twice over, offering a richer, deeper tone with a longer reverberation. One of the challenges in constructing cathedral gongs lies in draping them around the movement without touching each other as well as the case and the movement. In this instance, they also have to accommodate the complex asymmetric shape of the case and movement.
Everything is further housed in an inner titanium case to amplify the volume of the chimes. And as a result of this, the case could be sealed against moisture, with a depth rating of 30 meters, and yet deliver a clear and strong strike. The high-polish case is also made of titanium, which in addition to making a grand complication practical on the wrist, transmits sound extremely well due to its low density.
Safe and Sound
It is clear that Greubel Forsey made the decision not only to produce an incrementally better sonnerie, but also to enhance practicality. Naturally, as parts count starts to climb in a movement — a whopping 935 components in this case — mechanisms become a lot more fragile with more possible points of failure. As such, just as important as its sheer complexity are the security systems installed to prevent costly damages. To ensure flawless and continuous interaction of all the moving parts in such a highly complex ensemble, an elaborate string of safety and blocking mechanisms have been integrated into the movement.
Further, to ensure that a chiming sequence is not prematurely terminated when the mainspring is depleted, a mechanism automatically blocks the sonnerie barrel when the power reserve is too low to complete a full chime.
In effect, these mechanisms, along with its remarkably clear dial as well as its water-resistant titanium case, have made the Grande Sonnerie one of the most wholly practical and intuitive on the market. Although it is by no means a small watch, its dimensions of 43.5mm by 16.13mm start to seem reasonable when you consider the immensity of the movement. And in contrast to other chiming watches, its thickness does not feel incongruous to the design of watch.
It sounds almost cliché at this point, but as with all Greubel Forsey watches, the Grande Sonnerie is as technically impressive as it is meticulously finished. All screw heads are black polished and enhanced by chamfered slots while the jewels are embedded in polished gold chatons. The two striking hammers visible on the dial side have a flat black polish finish, along with hand-beveled edges and polished countersinks. The steel tourbillon bridge features a black polished top surface with polish bevels and four interior angles. On the reverse, the bridges and platinum rotor are also black polished along with being relief-engraved with the tenets of the brands. Even the bridge underneath the automatic winding rotor is decorated with a frosted finish and relief-engraving.
Due to its labor-intensive nature, production is extremely limited. But for those keen to meet this sonic masterpiece in person, there is one currently available at the new Sincere Haute Horlogerie (SHH) boutique at The Shoppes at Marina Bay Sands in Singapore.