Following the success of Jaeger-LeCoultre’s highly complicated Master Grande Tradition Gyrotourbillon Westminster Perpetuel earlier this year at SIHH 2019, the grand maison once again showcases just how far they can go with chiming watches; the most prestigious and exalted domain of mechanical savoir-faire. Introducing the new Master Grande Tradition Repetition Minutes Perpetuelle.
Limited to 30 pieces in a neoclassical silver-grained dial and 30 pieces in a deep blue translucent guilloche enamel dial, the new Master Grande Tradition Répétition Minutes Perpétuelle combines two of the most highly revered complications; a perpetual calendar and a minute repeater. Despite the multiple complications and the automatic winding system, all of which are known to add bulk to a timepiece, the case is only 13.7mm thick; surprisingly slim for a minute repeater. The 18k white gold case measures 43mm in diameter and comprises more than 80 separate hand-finished parts. Particular attention was paid to the ergonomics, from the deeply convex bezel and broad bevels on the lugs to the smoothly tapered minute repeater slide. Parts are alternately polished, satin-finished or sandblasted, the latter being highly challenging to execute on the exterior segments of a watch.
A dial of solid white gold is decorated with guillochage on century-old rose engines, each round of guilloché work repeated several times in order to achieve the correct depth of engraving. The perpetual calendar counters are then precision laser-welded onto the dial, before the remaining spaces are filled with translucent enamel in another multi-stage process. The enamel is then polished, resulting in the final dial of shimmering vitreous blue that changes in hue with the light and angle.
An extremely innovative security zone appears in the dial aperture near the axis of the hour and minute hand. This indication appears between the hours of 10pm and 1am, when adjusting the time or calendar is not advised due to the possibility of stressing or even damaging the movement.
A Chime like No Other
At the heart of the Master Grande Tradition Répétition Minutes Perpétuelle is a self-winding calibre 950 movement with an entirely novel gong configuration, that resurrects the idealised chime of antique pocket sonneries. Instead of lying flat in overlapping coils like the most commonly seen minute repeater gongs, the gongs of the Master Grande Tradition Répétition Minutes Perpétuelle depart radically from convention by incorporating unprecedented height and space. Two gongs, welded together at their base, travel in the same direction around the periphery of the movement, making one near-complete tour before dramatically arching upwards, traversing the entire height of the movement. They then diverge and take a terminal semi-arc around the other side of the movement, stopping just before their ends meet.
By maximising the space occupied by the element that creates sound vibrations — the gongs — the calibre 950 boosts its capacity for sound transmission. Further increasing this capacity is the proximity of the gongs to a larger proportion of the watch case, according to the acoustic principles that instinctively guide us where to position a relatively weak audio source in relation to a resonator (such as when a personal music player is placed in a glass dish to amplify the sound).
Signature chime innovations of Jaeger-LeCoultre, such as the square gong cross-sections and the articulated “trebuchet” hammers, ensure that the gongs are struck with the greatest possible impact and the least interference from hammer recoil. These set the stage for the meticulously engineered acoustic profile of the Master Grande Tradition Répétition Minutes Perpétuelle chime.
The lower-pitched gong takes a helical path from gong heel to tip. Though irregular in shape, its unidirectional flow allows it to vibrate in a way that creates the harmonic overtones giving fullness and balance to bass notes.
The higher-pitched gong switches direction, effectively folding back on itself like the tines of a tuning fork. This configuration emphasises the fundamental vibration of the gong, producing a purer tone that imparts the clarity and brilliance prized in treble notes.
This new optimised combination of chime volume and acoustic quality marks out new territory for Jaeger-LeCoultre in sonnerie watches, an expansion that is fully supported by the other customer-centric aspects of the Master Grande Tradition Répétition Minutes Perpétuelle.
The winding rotor of the calibre 950 is hidden within the movement, positioned between the perpetual calendar and minute repeater mechanisms, in order to a have full view on the mechanism at the back of the watch. The Master Grande Tradition Répétition Minutes Perpétuelle is thus continuously supplied with energy without the need to obscure a single finely finished component, whether chamfered, satin-finished, decorated with côtes de Genève, or any combination of the above.