“If you are at the top in watchmaking, you also have to prove it,” declares Thierry Stern, the CEO of Patek Philippe while introducing his latest masterpiece.
The Ref. 6301P Grande Sonnerie is a six complication wristwatch with a black enamel dial and a platinum case. Almost a decade in the making, this grand complication is the manufacture’s first wristwatch that “presents the grande sonnerie as the epitome of horological complications in its purest form.” It is complemented by a petite sonnerie and a minute repeater on demand.
“As a watchmaker, it is not only about learning how to create such a piece, which can take 15 to 20 years, you also need talent. Not every watchmaker who studies for twenty years will be able to work on a grande sonnerie. They need more than that. I like to say that it may be passion… There has to be a harmony in the piece that you build. There has to be an aesthetic of it. That is something you need to have in your heart. You cannot learn it in a school,” says Stern.
In addition to the three chiming complications stated above, the 6301P has three visual complications. There are two power reserve indications – movement power-reserve indicator and strike work power-reserve indicator- and the jumping seconds.
One of the greatest challenges for the engineers of grande sonneries is mastering energy flows and power reserves. Unlike in minute repeaters which are triggered on-demand, the grande sonnerie needs to have sufficient power reserve to automatically sound the required number of time strikes with uniform acoustic quality.
“It was very important for us to have a watch that can work for a really long time, both in terms of minute repeater, grand sommerie and the movement,” says Stern. “The grande sonnerie will work for 24-hours. That means 1,056 gongs in 24-hours. The power reserve for the time mechanism is 72-hours. So that a very powerful watch, especially if you look at the thickness of the watch. It is only 12mm thick. That was one of my targets. I did not want a watch that was too thick.”
To achieve these objectives, the engineers developed a new movement based on the calibre 300 of the Grandmaster Chime – the 20-complication watch launched to celebrate the watchmaker’s 175th anniversary in 2014. The resulting calibre GS 36-750 PS IRM accommodates 703 parts within its 37×7.5 mm dimensions.
The engineers also endowed the calibre GS 36-750 PS IRM with two tandem-connected twin mainspring barrels, one for the going train and the other for the chiming mechanism. The two twin mainspring barrels are wound with the crown pushed in and rotated clockwise to wind the going train and counterclockwise to wind the strike work. The four mainsprings feature slip bridles to avoid over tensioning. The strike work also possesses a uniform torque characteristic to assure optimized sound intensity.
The 6301P has three hammers of identical size and mass to guarantee a uniform strike for all three pitches – low, medium and high. This technical option requires more energy than systems with two gongs, thus the two twin mainspring barrels. It also complicates the watchmaker’s work when tuning each gong to achieve the much-coveted Patek Philippe’s signature sound.
The hours are struck on the low-pitched gong. The quarter hours are marked by one- to three-strikes in a high-low-medium sequence. The melody for the first quarter-hour (15 minutes) sounds once, for the second quarter-hour (30 minutes) twice and for the third quarter-hour (45 minutes) three times. Each quarter-hour sequence is automatically preceded by the number of elapsed hours, and followed by the number of quarter hours.
The petite sonnerie mode strikes the full hours but omits the repetition of the hours when striking the quarter hours. In the silence mode, the automatic time strike is switched off altogether. The selection of the strike work mode is performed with an innovative slide switch in the caseband at 6 o’clock. The petite sonnerie is selected by sliding the switch to the left, the grande sonnerie mode is in the middle, and silence mode is on the right.
The minute repeater is triggered by pressing the pusher in the crown at 3 o’clock. It strikes the number of hours the quarters as in the grande sonnerie mode, plus the number of minutes that have elapsed since the last quarter-hour on the higher-pitched gong. The minute repeater can be triggered at any time, even if the slide is set to the silence mode.
The small jumping seconds display at 6 o’clock has a mechanism derived from another 175th-anniversary model – the Ref. 5275 Chiming Jump Hour. The mechanism used to produce the jumping hour in the 5275 was modified to count the seconds in the 6301P. The small seconds hand jumps along the “railway track” minute scale every second, recalling the regulator clocks that were used in old watchmaking ateliers to synchronize the time.
The calibre GS 36-750 PS IRM can be admired through the sapphire-crystal case back, and as always, it fulfils all the strict aesthetic requirements of the Patek Philippe brand – that the complexity of a movement should never lessen its beauty and elegance. Some of the aesthetic details include the design of the movement bridges, especially the barrel bridge (a key element of grande sonneries), the transversal balance bridge, and the many reentrant angles that are very difficult to polish. The centrifugal governor, which regulates the speed of the time strikes, is decorated with exquisitely smoothed and polished finishes.
Another of Patek Philippe’s key principle is that a grand complication must also be pleasant to wear in everyday situations. “When I started my career at Patek, people did not wear their watches. Such a watch would have been put in a safe. Today the customer is wearing it every day. So the watches need to be stronger and easy to use,” says Stern.
“The main idea, for me, was that this watch should be wearable every day, 24-hours a day. So it had to be something very slim, very discreet… The watch is 44.8 mm wide. For Patek, that’s quite large. But for the market, where a lot of brands have watches going up to 45 or 46mm, 44.8 is really something quite impressive. It’s a beautiful watch to wear.”
The platinum case design is based on the Ref. 5370 split-seconds chronograph presented in 2015. There is a balance in its curves and rounded contours. The concave bezel offers a perfect transition from the slightly cambered sapphire-crystal glass and the countersunk satin-finished case flanks.
“It was quite clear in my mind to choose this design… The challenge for me was to make it in platinum for the Grande Sonnerie. It sounds crazy because platinum is the worst material for sound. It has about 30% more density [than 18K gold]. So the sound does not like to get out of this case. That’s why I said: we are going to work on platinum. I know it is going to be difficult with the sound. I know it is going to be difficult to fabricate the case, but we are Patek Philippe,” says Stern.
Like all Patek Philippe platinum cases, the 6301P has a small diamond set into the caseband at 12 o’clock, instead of the usual 6 o’clock position because of the slide switch for selecting the strike work mode.
As difficult as it was to fabrication the platinum case, Stern confesses: “the biggest challenge for me was the dial.” He then elaborates: “The complexity, when you are doing a black enamel dial like this, is to make the colour totally black. This comes from the purity of the materials you choose, the way you work on it, how you clean it, cook it, set it on the dial, its thickness, how we finish it, polished it… On this type of watch, I will lose three dials to make only one. But that’s the price we have to pay. For me, it was very clear. I am not willing to have a dial that is not perfect.”
The black grand feu enamel dial has a “glacé” finish. The applied Breguet numerals are slightly slanted for a classic look. The leaf-shaped hands are luminescent white gold. The displays for the hours, minutes, and subsidiary seconds at 6 o’clock are well proportioned. They are accompanied by the two power-reserve indicators: for the movement at 9 o’clock and for the strike work at 3 o’clock. Both are presented as semicircular scales identified with the inscriptions “Mouvement” and “Sonnerie” respectively. The timepiece is worn on a hand-stitched shiny black Alligator strap with square scales and a fold-over clasp.
As a matter of policy, Stern was unwilling to divulge the annual production numbers. However, he said: “now that we know how to fabricate it, I would say it would take us about a year, minimum, to fabricate such a watch. When I say minimum, it’s really the minimum because there can be a lot of problems. I am the last [of these problems] because I have to validate the watches and I am very strict.” He also added, with a hint of mischief: “The price is 1.25 million Swiss Francs. For that, you can also have the leather strap.”