Tech Insights - Acoustics under Pressure - GMT Magazine

The year 2016 proved pivotal for watches sounding the time and 2022 looks set to be a worthy successor. It was then that, after decades of incremental advances and marginal improvements, the quality and intensity of minute repeater watches made a double quantum leap. Until then, to put it simply, the case, gongs and minute repeater movement were three separate entities. The gong had to excite the rest of the watch, which was responsible for propagating the sound outwards. Yet all waves need coherence and watch is a naturally heterogeneous, discontinuous medium, which restricts sound. Jaeger-LeCoultre had already invented the crystal gong and welded the gongs to the watch glass to use the latter as a propagator.

Bulgari - The titanium container of the Octo Roma Carillon Tourbillon © Bulgari

“Isolating the resonator from the wrist and the case enables minute-repeaters to vibrate more freely and with a more intense sound.”

Ulysse Nardin Blast Hourstriker © Ulysse Nardin

A double break with Tradition

Six years ago, two innovations changed the state of the art. On the one hand, Audemars Piguet launched its Royal Oak Concept Supersonnerie. It consists of inserting a vibrating part between the movement and the caseback, which is pierced with holes. This component naturally amplifies the chime of movements that the brand did not need to renew. In addition to its formidable auditory efficiency, Supersonnerie saved Audemars Piguet time and money. On the other hand, Chopard revolutionized the manufacture of audible timepieces with its L.U.C Full Strike. Instead of metal gongs screwed to the movement and/or the case, the brand created a system in which the gongs are machined in the same block as the glass, and therefore in sapphire. The transmission is accomplished through a homogeneous medium to a vibratory membrane with direct access to the outside. And since homogeneity is crucial, at Watches and Wonders 2022 Chopard is launching the L.U.C Full Strike Sapphire whose entire case is made of sapphire. Visit our Saga pages to find out more about this first minute repeater entirely clad in transparent corundum crystal.

The caseback of the Audemars Piguet Code 11.59 Supersonnerie - The construction of the Audemars Piguet Supersonnerie system © Audemars Piguet

Membranes

The effectiveness of these two principles has led others to follow suit. On the one hand, Ulysse Nardin worked with the loud-speaker manufacturer Devialet for the Hourstriker. They interposed a vibrating metal membrane, connected to the movement by a lever, with case openings facilitating its expression. On the other hand, in order to separate the chiming mechanism from the shock-absorbing medium represented by the wrist, Bulgari has devised a case-decoupling system. The Octo Roma Blue Carillon Tourbillon features a double structure. First, a platinum grid that encompasses the lugs and ensures a smooth fit on the wrist; and then, a titanium secondary case housing the movement and dotted with resonant zones. The movement chimes, the container resonates and the platinum case does not dampen the sound. New creative paths and techniques are being envisaged for future projects with the Geneva acoustics specialist Goldmund whose high-end speakers are much appreciated by demanding music lovers. Finally, Patek Philippe has synthesized most of the above solutions and applied them to its Caliber R 27 PS. The Ref. 5750 “Advanced Research” adds a circular sapphire piece between the movement and the caseback, under the name of “ff” standing for fortissimo amplification module. Dedicated to the striking mechanism, it vibrates smoothly and its transparency reveals all. In a crowning touch, the sound is transmitted through four apertures in a titanium container. Technologies converge, great minds think alike and listening pleasure wins the day.