Audemars Piguet has become synonymous in the minds of many enthusiasts with the Royal Oak and its bigger, brasher spin-off, the Offshore, which turns 30 this year. But this release is a reminder that it became an incontrovertible member of the trinity by being nothing less than one of the greatest complication makers in the history of watchmaking. The Code 11.59 by Audemars Piguet Universelle RD#4 is the latest in the series of watches dedicated to building on an existing vocabulary of complications and pushing them in new directions. Developed over a period of seven years, the RD#4 isn’t just a grand complication but also one with an incredible number of technical solutions that drastically simplify user experience.

The watch was inspired by the L’Universelle pocket watch movement made by Audemars Piguet in 1899 for German watchmaker Dürrstein, Uhrenfabrik Union Glasshütte. Among its 26 functions were a carillon grande and petite sonnerie perpetual calendar, split-seconds, jumping-second and deadbeat-second chronograph. It was delivered as part of a trilogy, but, for many years, it was the only completed piece in the series. It is regarded by many as a rival to the Henry Graves Supercomplication and has become the centrepiece of the Audemars Piguet museum today.

Traditionally, a grand complication refers to a watch that combines three types of complications – calendrical, chiming and timing. However, in the RD#4, the calendar is a superior form of perpetual calendar that not only has an ultra-thin construction first realized in the RD#2 but also facilitates bidirectional adjustment of the date at any time without risk to the movement, as well as has a 100-year cycle encoded in its gear train, enabling it to account for non-leap years that occur every century. The timing mechanism, on the other hand, is a split seconds and flyback chronograph and the chiming function is a grande and petite sonnerie that incorporates the brand’s Supersonnerie technology first unveiled in the RD#1. Beyond that, it also has a flying tourbillon that houses a high-power balance wheel that debuted in the RD#3. All this is via the Calibre 1000, a full-rotor, self-winding movement that consists of a staggering 1100 parts, which make up 23 functions and 17 devices for greater ease of use and safety.

The basic philosophy behind a grand comp at this point of time in the brand’s history is to create something impressively complicated, but without sacrificing thinness, wearability or practicality. Despite the addition of numerous complications and functions, the watch measures just 42mm in diameter while the overall thickness of the movement is only 8.75 mm and when cased up, just 15.55 mm high, including a hunter case back. To put things into perspective, it is around the same thickness as a Sinn 356 Pilot Chronograph with a Valjoux 7750. Beyond that, all complications can be operated intuitively and with ease via three crowns with co-axial pushers on the right side of the case as well as three push-pieces on the left.

The top pusher on the left is for actuating the minute repeater, while the next two pushers are for advancing the day and the moon phase, respectively, essentially eliminating the need for a stylus. On the other side of the case, the top crown is for selecting the chiming mode while its pusher starts the chronograph. The date can be set bidirectionally via the central crown in the second position and its pusher splits the chronograph hands. And the last crown is for adjusting the month, forwards or backwards, while its pusher sends the chronograph hands back to zero. The remarkable ease of use across multiple functions no doubt belies complex solutions and security measures, which we will elaborate on when more information is available.

Perpetual Calendar

One of the most significant developments in the RD#4 lies with the perpetual calendar. While a regular perpetual calendar only encodes a four-year cycle in its gear train, taking into account leap years, the perpetual calendar in the RD#4 not only takes into account leap years, but also non-leap years that occur every century when the Gregorian calendar omits a leap year. As such, it does not require a manual correction until the year 2400 when the centurial year becomes a leap year once again, whereas a regular perpetual calendar will require an adjustment by one day on March 1 of the years 2100, 2200 and 2300. This makes the RD#4 more accurate than a perpetual calendar, but not yet a secular perpetual calendar, which encodes a 400-year cycle – that is, it takes care of non-leap years in three consecutive centuries as well as the leap year that occurs in the fourth century.

As with the RD#2, the calendar mechanism in the RD#4 has an ultra-thin construction that compresses two levels of a perpetual calendar into one. The end-of-the-month cam has been integrated into the date wheel, while the month cam has been combined with the month wheel. As such, these two wheels, as opposed to cams, are capable of driving or being driven directly.

It’s worth taking a slight detour here and mentioning that the main challenge with a secular calendar lies in having to negate the month program wheel in the event of a centurial year that is not a leap year. Details are scarce at the moment and what we know is that it relies on a 36-month wheel rather than the traditional 48, and as such the leap year is not encoded in this wheel.

The perpetual calendar also incorporates an instantaneously jumping moon phase display whereby two concentric discs, on which six different moon positions are printed, combine to form ten transitory stages from New Moon to Full Moon each month (every 29.5 days).

The moon phase and day can be corrected without the need for tools via two large rectangular pushers on the caseband. While the moon phase and day are adjusted unidirectionally as with a standard perpetual calendar, the date and month can be adjusted both forwards and backwards at any time via the crowns at three and four o’clock respectively.

Grande Sonnerie

The RD#4 is the latest in a series of chiming watches to benefit from the brand’s Supersonnerie technology that was introduced in the RD#1 in 2015.

One of the most crucial, and, moreover, quantifiable aspects of a chiming watch has to do with how well sound is transmitted from the vibrating gongs through the rest of the watch. Because the gongs typically occupy the circumference of the movement at the base, sound loss is inevitable as it has to travel through the movement, dial and crystal as well as laterally through the case band in order to reach the outside of the case.

The Supersonnerie was a game-changer in ramping up the volume of the chimes. The result of eight years of research in partnership with EPFL, the Swiss Federal Institute of Technology Lausanne, it introduced a soundboard between the case back and movement that was made from a special alloy and on which the gongs are attached. The goal was to produce a chiming wristwatch that would match the output levels of a voluminous pocket watch, and in so doing, allows it to be sealed against water. Most sonnerie or repeater wristwatches are not water resistant because gaskets only muffle sound and also, it is difficult to implement gaskets at the slide. The use of a pusher and Supersonnerie mechanism in the RD#4 essentially solves both problems, enabling the watch to attain a depth rating of 20 meters.

However, in the RD#4, the soundboard is crafted in sapphire crystal which has a characteristic ability to act as an acoustic amplifier while being able to showcase the movement. The crystal measures just 0.6 mm thick while the pivotable gold case back has been hollowed out to be as thin as possible and features a series of apertures on the side to boost sound amplification when the watch is worn on the wrist.

The strike train for the grande sonnerie and minute repeater are located on the dial side just before the perpetual calendar and as such, cannot be seen. A refresher: a grande sonnerie chimes the time – the hours and quarters – in passing – that is, it chimes the time automatically without any activation by the wearer. Because of this constant chiming of the hours and quarters, it demands a great deal of energy, thus requiring a dedicated mainspring barrel. In contrast, a minute repeater only chimes the time — hours, quarters and minutes — on demand. As such, the tension required to sound the gongs each time is not nearly as great as that for a grande sonnerie, so it only requires a small secondary spring that is charged when a pusher is depressed. Once released, energy is then discharged to power the strike train. The crown at two o’clock serves as a selector that allows the wearer to switch between three modes – grande sonnerie, petit sonnerie, or silence – while pushing the top pusher on the left side of the case arms the minute repeater.

Another innovation lies in regularizing the silent interval that typically occurs between the striking of the hours and that of the minutes when there is no quarter to be struck. Due to the position and shape of the racks, the time taken for the pin on the hour rack to come into contact with the opening of the quarter rack varies depending on the time, resulting in a dead time between the striking of the hours and that of the quarters, or between that of the hours and that of the minutes. Thus this configuration had to be revised to provide a more direct connection between the racks.

Flying Tourbillon

At six o’clock on the dial is a one-minute flying tourbillon which has a classic three-arm carriage anchored only at its base and houses a free sprung 3Hz balance fitted with poising and timing screws on its periphery. This is a configuration employed in the caliber 2950 as opposed to that in the RD#3 which, among other things, introduced a new balance wheel with weights that sit within its rim and set flush to its surface to minimize air resistance as well as to increase inertia for stable timekeeping.

However, the RD#4 employs the same optimized escapement used in the RD#3 to achieve a balance amplitude of almost 360°. The geometry of the escapement was modified such that the balance is able to accomplish a wider arc without overbanking, which occurs when the impulse jewel on the balance staff receives too much energy from the pallet fork that it rotates all the way around and knocks onto the other side of the pallet fork. This was accomplished by increasing the distance between the pivot of the pallet fork and that of the balance wheel. This way, the impulse jewel can travel further before overbanking, and mainspring torque can be safely increased.

Lastly, while the RD#3 uses a flat hairspring as a height-saving measure, the RD#4 has an overcoil, which is a traditional solution to maintain isochronism.

Split-seconds Chronograph

Last but by no means least, the watch incorporates a split seconds chronograph with a flyback function, making it possible to measure elapsed time with precision and reset that time in a blink of an eye. The chronograph relies on a horizontal coupling system with a rocking function to reduce the potential for stutter.

What’s even more unusual is that automatic winding bridge was designed around the splits-seconds mechanism, with the split wheel, clamp levers, spring and drive lever integrated within the confines of the rotor’s ball bearing housing. This has the benefit of maximising visual access to the movement and minimising thickness, bringing the height of the movement down by 1.1mm. Visible from here is that there is no isolator, which is additional wheel with a lever affixed to it and stacked on top of the chronograph seconds wheel to prevent friction of dragging over the heartcam. This is because the torque is sufficient to overcome the load.

Options

The Code 11.59 by Audemars Piguet Universelle RD#4 is offered in four configurations: white gold case with an opaline black galvanic gold dial, white gold case with an opaline beige PVD gold dial as well as two versions in white and pink gold wherein the dials have been reduced to a flange to showcase the finely decorated openworked movement. While the solid-dial versions are remarkably handsome and legible, which is more than can be said for most grand complications, the abundance of polished inward and outward angles on the openworked versions is enough to make the whole question of legibility obsolete.

Taken together, the fact that RD#4’s immense complexity is complemented not only by phenomenal usability (wearable dimensions, self-winding, water-resistance, ease of manipulation of multiple functions) but also compelling, immediately likeable aesthetics makes the watch the most wholly practical grand complication on the market.

Tech Specs

Code 11.59 by Audemars Piguet Universelle RD#4

Movement: Selfwinding Calibre 1000; 3Hz; 60-hour power reserve
Functions: Grande and Petite Sonnerie; minute repeater; flying tourbillon; “semi-Gregorian” perpetual calendar; flyback chronograph; split-seconds; hours and minutes
Case: 42mm; 18k white or pink gold; 8k hunter caseback opening onto the Supersonnerie sapphire membrane; water resistant to 20m
Dial: Opaline black galvanic gold dial; opaline beige PVD gold dial; openworked dial with black flange paired white or pink gold case
Strap: Black alligator strap with 18-carat gold AP folding clasp. Additional black textured rubber-coated calfskin strap
Price: Upon request