News SIHH 2012

The creation of a minute repeater watch requires not only decades of experience in some of the most exacting aspects of Haute Horlogerie, but also an in-depth knowledge of musical theory and of the physics of sound, combined with the ability to create a miniature instrument that is capable of transforming the precise, mechanical measurement of time into a universe of pure harmony.

Master Grande Tradition à Répétitions Minutes

Even the least musically-inclined listener will immediately notice the difference

The Watch Quote™ - January 31st, 2012



The unstinting commitment of engineers and master watchmakers in Le Sentier to the highest possible level of excellence in the field of Minute Repeater movements has been amply demonstrated in recent years.

Faithful to their customary approach, they have striven to uncover the techniques employed by the master watchmakers of days gone by. They have also been keen to go even further, never hesitating to take on new challenges by applying contemporary methods and technology. Having paid tribute and acknowledged the achievements of the past, today's watchmakers have not been slow to take up the gauntlet.


Innovation

In 2005, the launch of the Master Minute Repeater Antoine LeCoultre (Calibre 947) had already created a sensation with its patented crystal gong, constituting a major breakthrough in the world of watch sound. The gong heel was soldered to the watch's sapphire crystal so as to make the most of the sapphire crystal's properties of velocity to magnify the intensity and purity of the sound vibrations emitted.

After several years of research aimed at creating the purest sound possible, Jaeger-LeCoultre perfected a totally new shape of gong, used for the first time ever on the Master Minute Repeater watch in 2007. Consisting of a single part extending from the heel to the actual gong itself, this new design has a square cross-section rather than the traditional round cross-section, and a larger surface area that comes into contact with the hammer, which for its part can also strike with increased force. The gongs meanwhile were made out of a material for which Jaeger- LeCoultre possessed, and still possesses, the exclusive and confidential formula.

A succession of technical innovations were inspired by the Calibre 947, which consolidated its place in the history of watch sound when in 2009 Jaeger-LeCoultre unveiled the first minute repeater watch with a two-week power reserve combined with a regulator display.


Performance: exceptional sound

The magnitude of the project that the watchmakers had taken on gradually revealed itself during the course of a series of detailed studies undertaken with a view to achieving a sound hitherto unknown for a minute repeater watch. The first priority was to define the characteristics of the sound required and to establish parameters for it.

Sound is made up of four main components.

The volume is the strength of the sound as it is perceived. Expressed in decibels, it represents the sound pressure level to which the ear is exposed. It is a direct function of the acoustic pressure exercised on the eardrum. A variation of 10 decibels represents a doubling of the pressure exercised on the eardrum, and therefore a doubling of the perceived volume.

The second component of a sound is its duration. This represents the time that elapses until the sound emitted loses 20 decibels. The durations measured are of the order of a few hundred milliseconds.
The two other characteristics of a sound are its richness and pitch. The richness depends on the number of partials (or tones) perceived. The higher the number of partials, the more the sound is colourful and harmonious. The pitch corresponds to how high and harmonious is the value of the note struck, and to the respect for the principle of a third between two notes.

At the Manufacture, all measurements are taken using a microphone placed at a given distance from the sound source, but also with the assistance of a laser so as to obtain measurements that are not disturbed by the ambient medium.

Jaeger-LeCoultre specialists have studied each of these parameters so as to obtain the best possible combination. The result is quite simply breathtaking. The Jaeger-LeCoultre Master Grande Tradition à Répétitions Minutes produces a sound that has never been heard before in a wristwatch. With 64 decibels, durations of over 600 milliseconds and a richness of 9 partials, the sound produced surpasses any performance previously obtained with a wristwatch.

Even the least musically-inclined listener will immediately notice the difference.

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Minute repeater watches

The quest for a major watchmaking achievement


The technical difficulty of a repeater watch lies in the complexity of the mechanism that serves to read the time shown by the hands so as to transcribe it through a succession of strikes that, in the case of minute repeaters, count out the hours, quarter-hours and minutes. In the case of minute repeater watches, the barrel spring stores up all the energy needed to launch into the mechanical ballet that is to follow, thanks to the angular shifting action of the bolt. At the same time, what are known as the hour, quarter and minute racks (parts which have a series of aligned teeth) are wound up and set in position. An ingenious form of disconnecting-gear makes it possible to take out of action the strike-train and the centrifugal governor during the winding process. While the racks are being wound up, the hammers of the two gongs move aside from their positions to let the racks pass. This is why a minute repeater mechanism must never be re- wound when it is ringing.

Once the winding process has been completed, the energy of the barrel spring is liberated through the speed regulator, which uses the principle of centrifugal force to maintain a constant striking speed for the hammers.

The quality of the sound is largely dependent on the rapidity of the striking. If the hammer stays in contact with the gong, the latter's vibrations will be seriously disturbed, and the sound emitted will be of mediocre quality. The setting of the striking action is an essential and extremely delicate aspect of minute repeaters.

The production of sound by a watch depends on this mechanism, which requires the presence of two circular gongs rolled up inside the case, and of small hammers to strike them at regular intervals.

The sound quality of a watch that gives an acoustic indication of the time largely depends on the gongs, the essential parts for producing sound, in much the same way as in a piano the strings are struck by the hammers. The case then amplifies and enriches the sound emitted by the gongs by adding a variety of tones and harmonies to it.

Jaeger-LeCoultre Master Grande Tradition à Répétitions Minutes

Technical specifications.


Movement :Mechanical hand-wound movement,
Jaeger-LeCoultre Calibre 947,
Crafted, assembled and decorated by hand
Frequency: 21,600 vibrations per hour
Power reserve:15-day
Parts :413
Jewels :43
Height :8.95 mm
Diameter:34.7 mm
Functions:Hours, minutes,
Minute repeater,
Power reserve,
Barrel torque indication
Dial:Gold-plated, openworked
Markers:rhodium-plated applique markers
Hands :Dauphine type
Crown:1 crown for winding the watch, and for setting the hours and minutes
Push-piece :1 catch to activate the minute repeater
Case :ø 44 mm
Thickness:15.6 mm
Material :18-carat pink gold
Grystals :Sapphire
Water-resistance:5 bar
Straps :Chocolate-brown alligator-skin strap with pin buckle in 18-carat gold
Reference :Q50125 50 18-carat pink gold

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