When Patek Philippe releases a watch with “Advanced Research” in its moniker, you can be well assured that it will be something special in both its outward aesthetics and its inner technology. The most recent example was in 2017, when the Swiss high-horology maison released the Aquanaut Travel Time 5650G, the first timepiece equipped with the new Spiromax balance spring as well as a groundbreaking “compliant” time-setting device. This year, Patek Philippe, through the labor of its top-notch R&D division, has applied an ingenious new innovation to a chiming watch, a grand complication that has been one of its historical specialties. Here is a closer look at the Ref. 5750P “Advanced Research” Minute Repeater.
The essence of Patek’s technical accomplishment in this very limited timepiece (just 15 pieces) is that it features a method of amplifying the volume of the repeater’s time strike in a purely mechanical manner while simultaneously preserving the acoustic quality and doing so while maintaining the smallest possible dimensions. A module added to the bridge side of the movement works like a mechanical loudspeaker, using a triple-patented system with an ultra-thin oscillating sapphire wafer rather than the traditional vibrating membrane. This angular motion of this rigid, free-moving wafer produces a better propagation of sound in the confined dimensions of a watch case, while its transparent sapphire construction preserves a clear view of the movement through an exhibition caseback.
The minute repeater gongs are connected to the wafer by a steel sound lever that resembles a tuning fork on its other end. The hammers strike the gongs, the gongs transmit their oscillations to the sound lever, the lever amplifies them and transfers them to the wafer, which amplifies them even further by exciting the air layers above and below the sapphire crystal for a noticeably louder chiming sound. This system (which Patek Philippe refers to as “fortissimo”) helps propagate the sound waves on all sides of the watch case, which is made of platinum, a precious metal known for presenting the greatest acoustic challenge for a minute repeater watch. The fortissimo module solves the challenge with its use of an insulation rim made of a high-tech composite material that uncouples the amplifier from the movement; after the sound is routed from lever to wafer, it propagates through four narrow openings in a titanium ring at 12, 3, 6, and 9 o’clock and exits through a narrow slot between the caseback and caseband — ensuring that the case material chosen does not influence the sound quality. Furthermore, the fortissimo module allows the watch’s chimes to be heard at a six-fold larger distance than other repeaters — without sacrificing, Patek promises, the “harmonic quality and acoustic richness” for which its chiming watches are renowned.
The movement, Caliber R 27 PS, also replaces the steel minute repeater hammers of previous versions with new ones made of platinum, which provide a softer strike without reducing the rich resonance of the sound produced. The movement also uses platinum for the microrotor that winds the watch, replacing previous microrotors in gold; the metal’s greater density allows for the same winding power but a thinner design and thus a greater overall thinness for the caliber and, accordingly the case: at 40 mm in 950 platinum, the elegantly rounded case is just 11.1 mm high, just .57 mm thicker than Patek Philippe’s Ref. 5178 minute repeater with cathedral gongs.
The elaborately constructed, five-part dial has an openworked design inspired by spoked wheels on vintage automobiles, with a latticework motif underpinned by a snailed black background. The pattern is repeated on the small seconds disk at 6 o’clock, which uses a small marker rather than a conventional hand to trace the passing seconds as the disk spins. A pair of white-gold Dauphine hands indicate the time on kite-shaped hour markers in blackened white gold.
The rear side of the case offers through its sapphire window a view of the movement, including key elements like the hammers and gongs of the repeater and the tuning-fork-like sound lever, as well as the centrifugal governor with its pierced Calatrava cross emblem, a historical symbol of Patek Philippe. Maintaining a power reserve between 43 and 46 hours, the movement features other patented devices emerging from previous Advanced Research projects, including a Gyromax balance spring in Silinvar. Its platinum microrotor provides one more glimpse of the dial’s crisscrossing pattern, created with a special laser light-absorbing surface texturing technique. All 15 pieces of the Ref. 5750 “Advanced Research” Minute Repeater are mounted on a shiny orange alligator strap with black contrast stitching and a platinum folding clasp. The price is on request.