Grande Sonnerie

Grande Sonnerie is the most demanding acoustic complication that exists in mechanical watchmaking. It doesn't chime on demand like a minute repeater: it chimes en passant, that is automatically, at every hour and every quarter hour. At every quarter it repeats first the hours elapsed, then the quarters. The mechanism doesn't wait for you to press anything.

The distinction from Petite Sonnerie is precise. Petite Sonnerie also chimes en passant, but it doesn't repeat the hours at every quarter: at the quarter it only marks the quarters, the hour is struck only when the full hour arrives. Grande Sonnerie does more: at every quarter hour it repeats the hour and adds the quarters. The difference in terms of energy consumption is considerable, and almost all movements with Grande Sonnerie mount a second barrel dedicated exclusively to the striking mechanism, separate from the one that drives the timekeeping train.

The three-position selector — Grande Sonnerie, Petite Sonnerie, Silence — is standard structure. Blancpain in its Grand Double Sonnerie adopted four gongs instead of the traditional two, obtaining a richer carillon. Chopard in the L.U.C Grand Strike integrated in the same movement Grande Sonnerie, Petite Sonnerie and minute repeater: three overlapping acoustic functions, which requires a management of levers and gear trains that few manufacturers know how to handle. Audemars Piguet in the Code 11.59 added the silencing function via pusher at 2 o'clock, with a transparent sapphire soundboard that amplifies the sound.

From the workbench I have seen few examples of Grande Sonnerie return for servicing over the decades, and every time the preliminary work is to study the locking logic before touching anything. The cams for memorizing the hours and quarters must be in absolute synchronism with the timekeeping train: even minimal misalignment produces incorrect chiming. It's the point where the watchmaker stops working quickly and begins to count.

The complication fully enters the Grande Complication when combined with perpetual calendar and split-seconds chronograph: these three functions together historically define the pinnacle of mechanical wristwatch complexity.