Audemars Piguet Royal Oak Repeater Supersonnerie
Audemars Piguet is famous – rightly famous – for many things; among them the Royal Oak’s instantly recognizable eight-sided bezel and distinctive overall case architecture. What’s less well known in the general watch enthusiast community, however, is that there is quite a lot more to the history of Audemars Piguet than the Audemars Piguet Royal Oak Repeater Supersonnerie itself. In fact, for much of its history, one of the most distinctive elements of Audemars Piguet’s identity was its expertise as a complications maker. It’s a revelatory experience, if you can get there, to visit the Audemars Piguet museum, as HODINKEE did not long ago, and actually see and hear some of its historical production of minute repeaters. With the Audemars Piguet Royal Oak Repeater Supersonnerie , Audemars Piguet Royal Oak Repeater Supersonnerie put together a genuinely fascinating fusion of some of its newest visions of watch design, and some of its most historically – well, resonant – areas of technical mastery. The Royal Oak Concept Supersonnerie is a pretty major step in the evolution of minute repeaters, so before getting into the nuts and bolts, let’s talk a little bit about what a minute repeater is and how it does what it does. The minute repeater’s a very old complication; what it basically does is chime the hours, quarter hours, and the number of minutes past the most recent quarter hour – generally, on two gongs that sound two different notes. In a repeater, the time rings “on demand” or whenever you want to hear it (as opposed to “in passing,” as in a grandfather clock that rings the hour without you having to do anything). To operate a minute repeater, you usually have to press a slide set into the case-band, which winds a small mainspring barrel that powers the repeater gear train (otherwise every time you operated the repeater you’d run down the mainspring barrel). Minute repeaters are considered a “high” complication, and continue to be an acid test of real watchmaking skill, because making one that works well and sounds great is still something you can’t really automate. A repeater isn’t just a mechanism, it’s also a musical instrument, and the tempo and tone quality have to be painstakingly adjusted by hand. Getting a really great tone, a pleasing tempo, and adequate volume out of a repeater requires not just a lot of mechanical ingenuity; it also takes an understanding of casemaking, an instinctive grasp of musical metallurgy, and a great ear.
Traditionally the best repeaters were pocket Audemars Piguet Royal Oak Repeater Supersonnerie watches with gold cases, which delivered on all fronts: good volume; warm, pleasing tone; stately tempo. Getting the same out of a wristwatch is exponentially more difficult. The smaller case of a wristwatch (in some instances much smaller) smaller gongs, and weaker striking force in the hammers represent seemingly unsurmountable limits on performance. So it’s all the more amazing when you actually travel to Le Brassus and visit the AP museum, as we’ve been lucky enough to do, and hear just how much volume and warmth of tone you can get out of a wristwatch – below is our video, shot at AP Le Brassus in 2014 and we’d encourage you to give it a look, before going any further, as it really demonstrates just how amazing AP’s minute repeater production has been over the years. A lot of this knowledge was nearly lost during the 1970s and 1980s but fortunately Audemars Piguet has a significant number of pieces in its museum that offer clues to how to optimize the sound of a repeater. The investigation into the physical properties of its earlier phenomenal repeating watches was the spur behind the eight-year research program that finally culminated, last year, in the showing of a complex repeater with tourbillon and chronograph, in a Royal Oak Concept case, known as the Audemars Piguet Royal Oak Concept RD#1. This watch was shown last year but under certain restrictions, and especially notable was the dearth of really solid technical info.
As it turns out that was thanks to the fact that the Audemars Piguet Royal Oak Repeater Supersonnerie represented three patents pending, and since then the patents have been granted, which means Audemars Piguet can discuss the innovations in this watch in depth. The Supersonnerie, by the way, looks pretty much identical to the Concept RD#1 seen last year except for the coloration of the chronograph seconds hand, chronograph minutes hand, and the outer chronograph minutes track (all three orange last year, and yellow in the production piece we’re showing you now). So here we go. The first patent has to do with the gongs. AP puts a great deal of stock in maintaining and improving classical watchmaking, so these gongs are a classical material: hardened steel. They’re also tuned in a classical fashion: by filing the point where the two wire gongs are attached to the foot, or block, that holds them; and by carefully filing down the tips of each gong to adjust the tone. The patent here is really for the manufacturing process. Whether or not a repeater is pleasing to the ear has a lot to do with the musical interval between the two gongs – the process, which we hope to hear more about later this week, has to do with being able to make the gongs so that they come to the watchmaker already very close to optimum in terms of good tone and pleasant interval.
That said, as AP’s Claudio Cavaliere was kind enough to explain to us, you can’t take the watchmaker out of the equation entirely. Making a mathematically and sonically exact gong would be possible, but the result would sound, to the human ear – and as the sound is interpreted in the auditory cortex of the brain – somewhat artificial. Since a “pleasant” tone is a subjective experience, the gongs still need to be tuned by hand. The second patent has to do with the case construction. In a traditional repeater the main problem is that the foot of the gongs – the block to which they are attached – is screwed onto the mainplate. The movement mainplate is optimized not for the best acoustic properties, but for the best mechanical properties. Rigidity is less a problem than sheer mass; the bulk of the movement absorbs a great deal of sound energy rather than transmitting it to the parts of the watch that actually can in turn, vibrate, therefore amplifying the sound. AP has gotten around this dilemma and allowed both volume and tone to be optimized by fixing the gongs, not to the mainplate, but to a copper alloy resonance membrane sandwiched between the plate and the case back. If you look at the rear view of the movement above, you’ll see the hammers, but no gongs – that’s because the gongs are attached to the resonating membrane.
The case back itself has apertures that allow sound to be transmitted to the ear with minimum obstruction. This combination of materials and case architecture is key – you can make a repeater louder, but doing so without producing an unnaturally bright, artificial tone is not so easy and this is where the Supersonnerie really shines. The fact that the copper “sound board” can be made hermetically sealed to the inner case, allows the watch to have much better water resistance than is typical for a repeater: 20 meters. The third patent is for the regulator, or governor. The governor is what’s responsible for controlling the tempo of the chime, and in the Vallee de Joux (and elsewhere for that matter) the oldest and most tried and true method is using an anchor escapement at the end of a gear train linked to the repeater spring barrel. In modern times, centrifugal or air resistance governors have been developed as well. The advantage they have is that they are almost totally silent; the tradition anchor governor/regulator makes a distinct buzzing noise. For many connoisseurs this is considered the hallmark of traditional construction, but AP has developed a design for a traditional anchor governor that significantly minimizes the extraneous sound. This has been done by creating a special shape for the (steel) anchor that allows it to act almost like a shock absorber, so that the energy of impact is deadened; AP tells us that despite the use of a traditional anchor and steel for the material, the result of the new design is an anchor governor that is almost totally silent. Now that the veil of secrecy has been lifted a bit, you can probably see that there is a LOT more to tell about this watch but those are the basics. We’re very, very excited to get more deeply into this extremely interesting new vision of the minute repeater in coming weeks.
