A Grand Complication model housing a wealth of superlatives, the new Bulgari Grande Sonnerie Perpetual Calendar, Daniel Roth Collection arouses a great sensation in light of the combination of three highly exclusive complications, of the sheer number of its components, of the time required to assemble it, and of its impressive range of functions. 923 parts compose the movement; a master-watchmaker devotes a full year to creating it; and 20 different functions are provided by this one-of-a-kind model that will chime 433,580 notes each year in the course of 35,040 activations.
Presented at Baselworld 2011, this exceptional creation is an artistic masterpiece which, according to the most discerning connoisseurs of fine watchmaking, has already earned its place within the selective circle of the 10 most complicated watches ever presented.
Undeniably mastery
This exceptional watch is a natural heir to the line of Grande Sonnerie models introduced over the years by the Manufacture de Haute Horlogerie Bulgari in Le Sentier, which boasts undisputed and well-established mastery among the handful of companies capable of giving life to such a mechanism. Over the years, this longstanding experience has enabled to perfect the sound function by enriching it with three security systems thus allowing a smooth use with no risk of damage.
Creating such a masterpiece implies handling an imposing range of parameters that represent as many constraints: mastering energy, mastering the intricacies of metallurgy, mastering acoustics, mastering miniaturisation. The list is by no means exhaustive, and it is worth noting in passing that creating a Grande Sonnerie model is not something that is taught in watchmaking schools, since it exclusively depends on experience.
Only a patiently acquired expertise enables a watchmaker to devote an entire year to assembling and adjusting this absolutely unique work of art. The movement components of the Grande Sonnerie are not interchangeable: throughout the meticulous phase of preparation for assembling the parts, many of them are retouched and treated to various hand finishes that will enable the overall mechanism to operate in perfect harmony.
At least one year
While the movement of a Grande Sonnerie watch is already extremely complex in itself, the new model presented by Bulgari this year goes a step further and pushes the boundaries of horological complexity by adding a perpetual calendar to the audible musical indications. Moreover, the movement as a whole is endowed with the ultimate in precision, since the accurate timing of this sophisticated model is ensured by a Tourbillon.
In the case of the Grande Sonnerie Perpetual Calendar the process leading to its birth stretches over at least a year from the moment the watchmaker receives the rough movement parts. Everything is crafted within the Bulgari's Haute Horlogerie Manufacture in Le Sentier, nestled in the Vallée de Joux which remains the historical cradle of Grand Complication models.
Producing and finishing/decorating the movement parts takes six months, and this initial phase is followed by four months of assembly by the watchmaker. It is up to him to perform the necessary manual adjustments to ensure that the movement will run smoothly – after which he entirely dismantles it, cleans and checks the components before taking several more weeks to reassemble them.
A mechanical “conductor”
Grande Sonnerie mechanisms, a speciality in which the Manufacture de Haute Horlogerie in Le Sentier excels, call for a wide range of skills due to the automatic striking function which implies that they chime the quarters four times per hour, while repeating the hours each time. The energy reserve must thus be sufficient to avoid the user needing to rewind the watch every three hours. The Bulgari Grande Sonnerie Perpetual Calendar is therefore equipped with two self-winding barrels: one is dedicated to the usual timekeeping functions of the watch, and the other exclusively serves the striking mechanism and guarantees a full 24-hour power reserve in Grande Sonnerie mode (28 hours in Petite Sonnerie mode, which means the mechanism does not repeat the hours when it strikes the quarters). Finally, this virtuoso model is also a minute repeater capable of chiming the hours, quarters and minutes on request.
Achieving the sounds appears simple, but is in fact anything but: only a few master-watchmakers in the world – of whom three work for Bulgari – truly master this ultimate horological complication striking the hours, quarters and minutes on different tones involving four different notes reproducing the famous Westminster chime – C, D, E, G – so as to enable the ear to “read” the time. The steel hammers and gongs must thus be able to accurately chime the four notes of the scale by alternating between a variety of combinations, each signalling the hours, quarters and minutes according to the pre-selected mode: Grande or Petite Sonnerie, or Minute repeater. Each quarter has its own tune that may involve up to 12 different consecutive notes.
A matter of experience
Much like the string of a musical instrument, the striking mechanism composed of the hammers and gongs must sound the note with great accuracy – a real challenge involving a combination of metallurgical science and acoustics. The steel components are progressively adjusted by hand until the exact note is achieved, and the fundamental prerequisite for this work is once again experience.
First of all, the master-watchmaker meticulously fashions each of the gongs in such a way that they mould the shape of the mainplate. This is a tricky exercise, since the four gongs must be fitted within a confined space without touching each other. During this lengthy and difficult stage, the master-watchmaker must patiently adjust the gongs in order to give them a specific shape and thus position them accurately in relation to the hammers that will strike them.
The process is all the more complex in that the hammers and gongs must faithfully reproduce the four notes of the scale harmoniously and in step with an extremely accurate and regular cadence, according to the adjustments that are performed and that serve to optimise the sound power level, the tone, the rhythm and the precision of the activation. Experience and a good musical ear are of crucial importance here, since the master-watchmakers works on the length and thickness of the gongs to ensure that each note is different and thus emits a distinctive sound.
All the striking mechanism components are individually adjusted. The metal alloy wires are shortened and filed millimetre by millimetre, and their sound is tested by ear each time until the four notes – C,D,E and G – are achieved. From this point onward, the final stage involves putting the movement and its striking mechanism through its paces on a test bench specifically developed by the Manufacture de Haute Horlogerie Bulgari for its Grande Sonnerie models – a software programme that measures the sound, the melody and the cadence. All Grande Sonnerie watches by Bulgari are tested, controlled and tried inside a sophisticated dedicated chamber developed in collaboration with the Swiss Federal Institute of Technology Lausanne (EPFL. This device serves to fine-tune and enhance the sound quality of these masterpieces to a peerless degree of excellence. Given the number of components housed within the restricted space inside the case of the Grande Sonnerie Perpetual Calendar, the sound intensity is quite simply exceptional.
Perpetual Calendar: next adjustment in 2100
This pure watchmaking masterpiece single-handedly symbolises the degree of mastery the Brand has achieved in the field of Grande Sonnerie models. The Manufacture de Haute Horlogerie Bulgari has gone a step further by combining the Grande Sonnerie with one of the most poetic complications: the Perpetual Calendar. This complex device provides a full set of calendar information while automatically taking account of the lengths of the various months as well as of leap years: days of the week, months, years, date and moon phases.
The sophisticated Perpetual Calendar developed by the Manufacture Bulgari will operate accurately without any need for adjustment until the year 2100, while taking account of months with 28, 29, 30 and 31 days. At that point, since 2100 will be a leap year, a correction will be necessary to enable the mechanism to once again provide precise calendar information until the year 2200, also a leap year.
The regulating organ ensuring the smooth running of the mechanism with bidirectional automatic winding, optimised by the heavy 18-carat gold oscillating weight, is enhanced by the delicately crafted Tourbillon mechanism visible through the back of the watch. The generous sapphire crystal opening simultaneously ensures optimal sound amplification as well as an ideal view of the movement and its components, particularly by revealing the steady dance of the hammers hitting the gongs when the striking mechanism is activated.
The Grande Sonnerie Perpetual Calendar has an 18-carat pink gold dial featuring a specific colour finish – anthracite and snailed treatments combined with black lacquer and openworking – that makes each model truly unique. Each display is carefully arranged and enables one to read off the day of the week and months on two sapphire discs at 9 and 3 o'clock, while the moon-phase appears at 12 o'clock next to the striking-mechanism power-reserve display. At 6 o'clock, the date is shown by a hand running over a graduated day of the month circle combined with a leap-year indication.
A complex case construction
The sapphire crystal on the back of this masterpiece reveals the beating heart of the watch and its steel parts finished in harmony with the noblest watchmaking traditions, along with its four hammers, the tourbillon carriage, and the centrifugal governor serving to regulate the cadence of the striking mechanism. The mechanism is housed within an elegant 18-carat pink gold case featuring a complex construction and fitted along its sides with a minute repeater pusher at 9 o'clock, the strike/silence and Grande/Petite Sonnerie selectors at 11 and 7 o'clock respectively. The crown at 3 o'clock serves to adjust the usual timekeeping functions of this timepiece that is guaranteed water-resistant to 30 metres.
This Grande Sonnerie Perpetual Calendar is a one-of-a-kind creation. It is delivered with a sophisticated packaging echoing the design of vinyl record players, and equipped with an integrated watch winding system and a natural amplification of the chime.
Technical sheet
Movement
Manufacture movement, Cal. DR 5307, comprising 923 parts & 82 jewels.
Grande Sonnerie with Westminster chime, 4 hammers, Perpetual Calendar, Minute Repeater, Tourbillon & Moon Phases.
Indication of the hours and minutes, day of the week and months, leap years, moon phases and date; double power-reserve indication for the movement and the striking mechanism.
Case
18-carat pink gold, crown at 9 o'clock for time adjustments; strike/silence and Grande & Petite Sonnerie selectors at 10 and 7 o'clock respectively, minute repeater pusher at 9 o'clock.
Sapphire crystal set into case-back revealing the movement.
Water-resistant to 30 metres.
Dial
18-carat pink gold with alternating lacquered finish, opaline anthracite & snailed surface treatment, openworking; semi-transparent sapphire discs indicating the days and months.
Strap
Black alligator leather strap, 18-carat pink gold triple-blade folding clasp.
