Breguet reinvents this year the minute-repeater, one of the most coveted horological complications by taking an original approach with the Tradition 7087. This timepiece is presented in a completely new light, both in terms of approach and result. Breguet’s watchmakers and engineers made a clean sweep of the usual methods to design their exceptional timepiece around the sound it produces. Using simulations they first synthesised about a hundred thousand sounds, which they classified into categories according to psychoacoustic criteria.
These sounds were listened to and evaluated to identify the two desired notes with the aim of revolutionising sound perception by modern harmonies and tuning. The construction of the timepiece was then undertaken to reproduce the selected sound mechanically. This unprecedented approach determined the choice of every aspect of the watch, the innovations inherent in the shape of the components and the materials used for decoration. The brand’s characteristic styling was therefore carefully planned so as not to interfere with the desired sound.
The gong springs, invented in 1783 by Abraham-Louis Breguet to become the essential components of a minute-repeater, have been entirely reworked and attached to the bezel to favour the transmission of vibrations. The radiating glass that is found on the Reine de Naples Sonnerie au Passage 8978 is here replaced by a radiating bezel screwed to the case band with three pillars allowing the bezel and glass to vibrate freely. This innovation results in improved sound emission, particularly at low frequencies. While the exterior parts of the watch generally transmit mostly the higher frequencies, the radiating bezel offers a wider range with several frequencies below 4,000Hz.
Unlike many minute-repeaters in which the travel of the hammers is parallel to the movement of the watch, this Breguet Tradition 7087 has hammers that strike vertically from the movement towards the bezel. Thanks to this technique, the mechanical vibrations are very efficiently transformed into sound waves. The hammers entailed a supplementary innovation that has been patented: a semi-active buffer. Minute-repeaters usually have a buffer spring to prevent the vibrating gongs from being struck twice. However, because the buffer spring comes into play before the hammer strikes the gong it partially reduces the hammer’s force. The company’s watchmakers have therefore invented a so-called semi-active buffer that maximises the hammer’s energy while eliminating the risk of a double strike caused by the vibration. To achieve this they devised an articulated damper that is synchronised with the strike of the hammer, which is immediately pulled back by a spring.
As in the Classique La Musicale 7800 model, a membrane has been placed on the back of the case. Linked to the bezel, it vibrates the air in the acoustic cavity between the pierced caseback and the membrane. The volume of the minute-repeater is thus increased, while the sounds from the mechanism are filtered. Here Breguet’s research in acoustics resulted in a gold membrane affixed to a sapphire crystal providing an unhindered view of the movement, unlike the metallic glass membrane of the reference 7800.
The materials were also chosen according to the results of Breguet’s scientific research into vibroacoustics. The model thus comes in a white gold or rose gold case with a gong made from the same material. The base-plate and bridges of the movement are in titanium. Along with an appropriate sizing of the parts, this material serves to avoid propagating the noises from the mechanism by filtering their transmission to the exterior. Designed to spread and amplify the sound, the latter is distinguished by its ability to reproduce the sound of the gongs in all its majestic purity. The Manufacture Breguet is the first to use titanium in a movement for acoustical reasons, mainly because this material is so difficult to work with.
In addition to all these innovations is the use of a magnetic governor in this Tradition Répétition Minutes Tourbillon model, as was the case in the Classique La Musicale watch. Unlike a traditional governor, this patented system consists of silver weights passing beneath magnets and slowed down by magnetic fields. An adjustment spring allows the magnets to be moved closer to or farther from the magnetic field. The noise is thus reduced and wear avoided, while the speed is kept constant to maintain the strikes at a steady rhythm however many they may be. Although it’s essentially the same system as that in the Classique La Musicale model, this magnetic governor has been the subject of much calculation and optimisation to adapt it to the minute-repeating mechanism. This innovative device can be seen on the dial side through the sapphire-crystal glass. Beyond its unusual technical features, this Tradition 7087 watch is made as a tribute to the company’s long history, which is why it is naturally endowed with a tourbillon. This emblematic compensation device, invented by Abraham-Louis Breguet in 1801, has made a lasting impact on horological history by preserving the regulating organ from the perils of gravity. But the Tradition 7087’s real compliment to the pocket-repeaters of old is the bayonet pusher to activate the striking mechanism. After releasing the pusher by slightly unscrewing it, the user will be careful to lock it by screwing it in again. Thereafter a simple press will be enough to trigger the audible mechanism. And finally the transmission from the barrel for the strike to the minute-repeater is by chain, as in the old pocket-watches, notably the N°160 watch made for the queen of France, Marie-Antoinette.
Apart from the many innovations improving its acoustic qualities, this watch incorporates other already proven developments. In particular, this self-winding timepiece is fitted with a peripheral rotor. While this system was originally invented to save space, it was selected in this case to make the movement perfectly visible and to maintain the stylistic coherence of the Tradition collection. It is also equipped with the high-energy barrel, which first appeared in reference 5277 and 5377. Finally, this model has a silicon Breguet spring, an invention that is increasingly available in the company’s watch models.
In terms of styling, this unique piece has a contemporary design, which, like the entire Tradition collection, offers the major parts of the movement on the dial side to the admiration of the viewer. The many decorative features cherished by the company are also present. The hours and minutes are shown by open-tipped hands in blued steel, while the dial is engine-turned by hand. The case is decorated with fluting on the case band and has welded lugs.
Model: Breguet Tradition Répétition Minutes Tourbillon 7087
18-carat rose gold with delicately fluted case band
Double-paned sapphire-crystal caseback
Welded lugs with screw bars
Silvered 18-carat gold, engine-turned and offset at 1:30
Individually numbered and signed Breguet
Hours chapter with Roman numerals
Breguet open-tipped hands in blued steel
Self-winding movement with minute-repeater and 60-second tourbillon at 6 o’clock
Numbered and signed Breguet
Titanium base-plate and bridges
Cal. 565DR. 16 lignes, 60 jewels
Magnetic strike governor
80 hours power reserve indicator in an aperture at 12 o’clock
Bi-directional platinum winding rotor on the periphery of the movement
Tourbillon bridge in titanium
Inverted lateral lever escapement with silicon pallets
Breguet balance-wheel on a Breguet silicon spring
Balance frequency 4Hz. Adjusted in six positions
Also available in 18-carat white gold: Reference 7087BB/G1/9XV