Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar Marks Another Power-Reserve Milestone

Back in 2019, Vacheron Constantin wowed the watch-enthusiast community with a perpetual calendar watch that was, for lack of a better term, the most “perpetual” such timepiece ever introduced. The Traditionnelle Twin Beat Perpetual Calendar incorporated a patented technology that enabled it to run for at least 65 days without winding or re-setting. It accomplished this unprecedented feat thanks to its movement, Caliber 3610 QP, which uses two separate balances oscillating at two frequencies — a "slow," energy-saving 8,640 vph (1.2 Hz) and a speedy 36,000 vph (5 Hz) — and a mode selector that enables the wearer to switch from "Active" to “Standby” mode, the latter for extended periods of non-wear. As if this horological invention were not impressive enough, today Vacheron introduces a new version of the timepiece with an optimized movement that extends the months-long power reserve to a full 70 days.

So what’s new in Vacheron Constantin's latest perpetual calendar? The clever architecture at the heart of the movement is still the same, with two independent gear trains powered by a series-connected co-axial double barrel; two balances are driven by a single mainspring barrel for efficient energy distribution, and the balance wheels, only one of which can operate at a time, are linked by a differential. A push-button-operated system, set into the case side at 8 o’clock, switches between modes while the movement continues to display the time and all the calendar indications, despite the necessity of stopping one balance to start the other. 

In this new version of Caliber 3610 QP, Vacheron uses three differentials — the first one to ease the transition between gear trains; the second, to split the energy from the mainspring to the slower, 1.2-Hz “Standby” gear train and its larger balance wheel, which also incorporates a specially developed hairspring, thinner than an actual human hair; the third, to efficiently distribute the energy between two power-reserve indicators, which are designed to use a single hand in a single counter with two scales. Additionally, Vacheron’s watchmakers developed a new, patented double-gear spring-winding system that requires four times less torque to drive the calendar’s instantly jumping displays; this means that date changes are much less energy-intensive, resulting in enough saved energy to add five full days of autonomy to the movement’s already precedent-shattering power reserve, from 65 days to 70.

The 42.5mm case of the Traditionnelle Twin Beat is made of 950 platinum and checks in at a relatively slender 12.3mm thick despite the array of complication and horological sophistication offered by its inner mechanism. The dial consists of a lower sapphire section that reveals the movement’s mainplate, sandblasted and treated with NAC galvanic coating, and an upper section in 18k gold, finished in slate gray and a radiating, hand-applied guilloché pattern. The Dauphine hour and minute hands are made of white gold, while the calendar displays (plus the dual-mode power reserve) are laser-etched onto the dial’s sapphire glass surface with a frosted finish that offers contrast and high legibility against the movement beneath. 

The back of the 480-part movement features a similar array of NAC galvanic finishes, along with hand-bevelled bridges embellished with côtes de Genève.The mainplate is sand-blasted, while the large mainspring barrel cover has a circular satin finish. Like the vast majority of Vacheron Constantin’s in-house calibers, this one has earned the prestigious Hallmark of Geneva for its elite level of both horological excellence and aesthetic beauty. The watch is mounted on a textured calfskin strap with a pin buckle in 950 platinum. The MSRP has yet to be announced, but the original version was priced just shy of $200,000; let’s see if those five extra days equal a few extra bucks up front. You can learn more at vacheron-constantin.com