Minute Repeater Resonance: Armin Strom Masterpiece 2 Is A World First Two-In-One

Press Release

Minute Repeater Resonance: Armin Strom Masterpiece 2 Is A World First Two-In-One

The Minute Repeater Resonance is not simply a masterpiece, it’s Masterpiece 2!

Minute Repeater Resonance by Armin Strom, the world’s first and only resonance chiming wristwatch, offers two-in-one for double the pleasure. Two complications, resonance and minute repeater; two vertically-stacked independent movements; two forms of resonance (oscillators and sound propagation); two independent mainsprings in one barrel; and two top development teams in Armin Strom (resonance) and Le Cercle des Horlogers (repeaters).

Inspired by the Bern’s centuries old chiming tower clock, the Minute Repeater Resonance is limited to just 10 pieces in celebration of the 10th anniversary of the Armin Strom manufacture. Masterpiece 2 highlights both the phenomenon of resonance and the sonorous chiming of the time by placing all of the action up front and center dial side.

Activated by a slider on the left side of the case band, two hand-polished hammers at 11 o’clock and 1 o’clock respectively chime the hours and minutes on two three-dimensionally curved gongs encircling the hour/minute subdial. The hammers are visually and technically balanced by the two independent regulators – one for each of the two movements – at 5 o’clock and 7 o’clock.

The case is in Grade 5 titanium for optimal sound transmission (and comfort), and its 47.7 mm diameter allows for a generous volume for the sound to propagate from. The sonorous chimes are also enhanced by attaching the gongs directly to the case.

 A specially developed security system maximizes ease-of-use by protecting the minute repeater from accidental damage by blocking operation during time-setting and winding. Fully visible between the two oscillating balances is Armin Strom’s patented Resonance Clutch Spring – the key to Armin Strom’s mastery of resonance – and the result of three years of intensive research and development. While it has been long known that resonating coupled oscillators in watch and clock movements improves accuracy, less known is that resonance also conserves energy. Armin Strom’s laboratory testing has revealed gains in precision of 15-20%.

Under a virtually invisible sapphire crystal dial, the dual balances oscillating in synchronization and the two hammers striking the time, the Minute Repeater Resonance stages an unparalleled horological spectacle for both the eyes and the ears. The Armin Strom Minute Repeater Resonance is a limited edition of 10 pieces in Grade 5 titanium in honor of the 10th anniversary of the manufacture. There will be no more editions.

Minute Repeater Resonance: Inspiration

For the 10th anniversary of its fully integrated manufacture, Armin Strom decided to develop a world-first masterpiece fully highlighting the brand’s savoir-faire. As the industry leaders in resonance, including the brand’s laboratory-certified resonance technology was an easy choice. But Armin Strom’s chief watchmaker Claude Greisler wanted something more: a grand complication. Inspiration for a minute repeater came from an unusual source: a sixteenth-century tower clock. Armin Strom is based in Bienne in Switzerland’s canton of Bern, and Greisler wanted to pay homage to the region. While the French-speaking region of Switzerland is known for a multitude of famous historical timepieces, Bern has far fewer. But it does have one landmark clock that everyone in the region knows: the thirteenth-century Zytglogge. The clock in this tower has not only served as the city’s main clock for more than 500 years, the tower also served as the reference point for travel times indicated on stone markers along the main cantonal roads.

This clock tower supposedly helped Albert Einstein hone his special theory of relativity while working as a patent clerk in Bern. The impressive tower clock is animated with automatons: four minutes before the change of the hour, a cock crows, a bear (the symbol of Bern) makes his rounds, and a jester takes the liberty of announcing the hour in advance. And at the top of the hour (and on the quarters), the clock chimes the time for all to hear.

Serge Michel & Claude Greisler

Minute Repeater Resonance: Development

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.


In the pursuit of horological accuracy, precision, and rate stability, resonance has usually involved using two independent movements connected to allow fine tuning of the distance between them. Until Armin Strom, precise adjustment of the distance between the two regulators has been necessary to incite resonance. However, the Armin Strom Resonance Clutch Spring eliminates the necessity for fine tuning the distance, ensuring a much more reliable and efficient resonant system only taking up to 10 minutes to synchronize. The idea of resonance has endured for three centuries for a reason, but that doesn’t mean you can’t improve upon it.

Armin Strom’s patented Resonance Clutch Spring is an innovative way of upgrading an old concept, one that is horology’s very reason for being: precision and accuracy. Note that the CSEM (Centre Suisse d'Electronique et de Microtechnique) has officially certified Armin Strom’s resonance system based on the clutch spring as being a true system in resonance.

What is resonance?

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

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