Armin Strom as masters of resonance movements wanted to work in partnership with masters of chiming watches, and Greisler knew the perfect person and team: his old friend Alain Schiesser, founder of Cercle des Horlogers, with whom he had worked with in the past at Christophe Claret. Working behind the scenes, Le Cercle des Horlogers has developed around half of the minute repeaters launched by prestigious Swiss brands over the last few years.

Originally the minute repeater mechanism had been envisaged to be in the traditional position at the back of watch, but the team decided that it deserved equal billing with the resonant regulators dial side where it could be appreciated by all. This brought many technical challenges of its own. Armin Strom not only wanted the resonant regulators and minute repeater hammers and gongs to be fully visible on top of the movement dial side; Greisler and his team did not want appreciation of the animated mechanisms to be potentially diluted by the associated gearing necessary to drive the repeater and going train for the time display. So the movements are inverted with the pinions driving the repeater hammers and hour and minutes transversing the two vertically stacked calibers.
 

They say necessity is the mother of invention and that’s certainly the case here. Space constraints meant that there was insufficient room for separate large mainspring barrels for each of the two movements, so Armin Strom developed an innovative single barrel with two independent mainsprings inside, each driving its own movement.

The high visibility of the complications dial side also dictates that the watchmakers have to pay very special attention when assembling and regulating the watch as the slightest scratch or mark on the beautifully hand-finished surfaces would be visible to all. Skeletonized bridges and plates (an Armin Strom specialty) allow visual access through the sapphire crystal dial deep into the movement. While the vast majority of the components were produced in-house at the Armin Strom manufacture, the gongs were made by Le Cercle des Horlogers in a process involving more than 30 different stages including multiple thermic treatments.

While the exact process is a closely guarded secret, it is said to be very similar to Patek Philippe’s process for making gongs. All components are finished to the very highest level, but of special note is the tremblage hand-engraving on the large golden balance cocks supporting the two oscillating balances. While titanium is the perfect metal for both transmitting the resonating sound from the gongs to the ear and ensuring that the watch is relatively light and comfortable to wear, it is a ‘cold’ metal; this coolness is balanced by the warm gold.
 

A body in motion causes vibrations in its surroundings. When another body with a similar natural resonant frequency to the first receives these vibrations, it absorbs energy from it and starts vibrating at the same frequency in a sympathetic manner. For example, a trained singer can hold a note causing a tuning fork tuned to the same frequency to vibrate. For the oscillators of a watch movement to be able to synchronize with each other, they have to be closely tuned. Imagine a small child trying to synchronize steps with an adult; the child is unlikely to synchronize for more than a few steps as the systems are too dissimilar to resonate. Or imagine yourself pushing a child on a swing: the child and the swing make a natural pendulum, which will have an inherent natural frequency (speed of swing back and forth). If you push at the wrong frequency (too fast or too slow) then you are likely to block the motion and slow the swing down; however, if you push at or near the natural frequency of the swing then you will increase the amplitude (distance the swing moves) of the child/swing system.

In horology, the phenomenon of synchronized motion has fascinated watchmakers since the time of Christiaan Huygens (1629-1695). Huygens, inventor of the pendulum clock, was the first to discover the resonance of two separate pendulum clocks, which he logically surmised should keep slightly different time. When hung from a common beam, however, the pendulums of the adjacent clocks synchronized; subsequent researchers confirmed that the common wooden beam coupled the vibrations and created resonance. The two pendulums functioned as one in a synchronous manner. In the eighteenth century, Abraham-Louis Breguet demonstrated his mastery of the physics with his double pendulum resonance clock. An outside shock slowing down one of them increases the speed of the other one by the same amount; but both will strive to get back in resonance, averaging and minimizing the effects of the outside influence as they find their rhythm. What was true for Huygens’ and Breguet’s clocks is just as true for Armin Strom’s wristwatch.

The advantages of resonance are threefold: 1) stabilizing effect on timekeeping, meaning better accuracy; 2) conservation of energy (think of a professional cyclist riding in the shadow of another cyclist in a racing situation); and 3) reduction of negative effects on timekeeping accuracy due to outside perturbation such as shock to the balance staff, which in turn keeps the rate more stable (better accuracy). While the advantages of resonance have been known for centuries, only a handful of clockmakers and watchmakers have created timepieces deliberately and successfully exploiting the phenomenon of resonance, including An