Review: Armin Strom Mirrored Force Resonance ST22-RF.75

Our hands-on review of the new Armin Strom Mirrored Force First Edition ST22-RF.75 with lot of pictures and price CHF 58,000

The Armin Strom Mirrored Force Resonance ref. ST22-RF.75, the new generation of the acclaimed model first introduced in 2016, is definitely one of those wristwatches that you would like not to have to return once the review has been completed.

With its distinctive resonance technology, contemporary design and Haute Horlogerie finishes, the new Mirrored Force Resonance is indeed one of our favourite timepieces launched in 2022.  

This unique wristwatch, characterised by two balance wheels on the dial side, features a patented dual regulator mechanism that increases precision and rate stability by taking advantage of the resonance physical phenomenon.

Due to resonance, two oscillating mechanisms can transmit vibrational energy between each other, each affecting the other’s rate (to learn more about mechanical resonance applied to watches, you can read our feature article "In pursuit of precision: mechanical resonance and watches").

After several years in research, Armin Strom found that the most effective way to create resonance was to link the two oscillators via a shared suspension, their patented Resonance Clutch Spring. 

Developed and produced in-house, this sophisticated spring connects two sets of oscillators - mainsprings, gear trains, escapements, and balances - which influence each other and eventually synchronize at a preferential frequency.

When the two balances find a concurrent rhythm in opposite directions, there are three key benefits: a stabilizing effect on timekeeping, a conservation of energy, and a reduction of negative effects on timekeeping accuracy due to outside perturbation.

For example, an outside shock that slows one of the balances down increases the speed of the other one by the same amount; both balances will strive to get back in resonance, thereby averaging and minimizing the effects of the outside influence as they find their rhythm.

Crafted from a single piece of steel, the Resonance Clutch Spring quickly bring the balance wheels into resonance while also contributing to make the watch more resistant to shocks or vibrations. In fact, a theoretical precision would be pointless without reliability and consistency.

Following our presentation article of last May, we had the opportunity to spend a few days with the new Mirrored Force Resonance ref. ST22-RF.75 and we are now delighted to share our pictures and impressions. 

Presented in stainless steel in this first edition, the case design has been beautifully streamlined with more slender proportions (43 mm x 11.55 mm vs 43.40 mm x 13 mm of the previous generation).

The small embossment at 6 o'clock is a nod to the Armin Strom “lip”, a signature element of the brand that was originally designed to offer a surface for personalizing the watch with engraved initials.

The clean lines of the case are highlighted by its meticulous finish alternating polished and satin-brushed surfaces. Water resistance is guaranteed up to a pressure of 3 ATM (approx 30 metres / 100 feet).

The watch sits nicely and comfortably on the wrist (the one in our pictures is 17.7 cm / 7") thanks to the ergonomically designed and slimmer lugs.

The raised sapphire glass box makes it possible to appreciate the three-dimensional architecture of the movement from multiple angles while also amplifying the play of light.

The two balance bridges have been openworked to better harmonise with the two synchronized balanced wheels and the skeletonised hands indicating hours and minutes on the offset dial on the right. 

Created in a warm “Black Gold” colour exclusive to this series, this elegant opaline dial is enhanced by the snailed outer chapter. The stainless steel hands are manually crafted by Armin Strom.

At 11 and 7 o'clock we find the two running seconds indicators which rotate in mirrored clockwise and counter-clockwise motions visually tracking the state of resonance.

A rapid pressure on the push button at 2 o’clock enables the seconds to be reset to zero and synchronized, for example, with a time signal. 

The complete dial is indeed perfectly executed and finished, with the two connected oscillators offering a truly mesmerizing effect.

If the power reserve has been exhausted and the movement requires to be wound again, the twin balance wheels will synchronize in less than ten minutes. In case of a disturbance such as a shock, it takes only a few minutes for the two balances to find their resonant rhythm once again.

This behaviour is explained by the fact that the resonance clutch spring connects the balance spring studs which receive the impulses rather than the balance wheels.

While improving the watch’s overall precision, the beauty of the resonance implementation used by Armin Strom also stands in the possibility to observe this phenomenon, and admire how the two resonant regulators work in a sympathetic manner, while wearing the watch on the wrist.

The caseback of the Mirrored Force Resonance is another pleasing surprise. The transparent sapphire crystal showcases more elements of the manufacture Calibre ARF21, a 276-part hand-wound movement that beats at the frequency of 3.5 Hz (25,200 vibrations per hour).

Guaranteeing a power reserve of 48 hours, the two skeletonised mainspring barrels can be observed while they simultaneously wind. The symmetry of the movement is accentuated with its mirrored arrangement of open bridges and gears, an open execution that brings to mind the history of the brand as a preeminent maker of skeleton watches. 

The ratchet wheels and pawls take their inspiration from those found in pocket watches and provide a smoother tactile experience when winding.

The engraved main plate outlines the specific characteristics of the Mirrored Force Resonance in raised text.

The impeccable Haute Horlogerie finishes include wide hand-polished chamfers on the bridges and countersinks and a mix of satin-brushed and mirror-polished surfaces.

The First Edition of the Mirrored Force Resonance is limited to 25 individually numbered (xx/25) pieces and is made even more special by the two finger-style bridges between the ratchet wheel and barrels that are crafted in white gold. 

The watch is matched to a blue alligator leather strap with white stitching and a double-folding stainless steel clasp whose perfect execution is a demonstration of the attention that the brand pays to even the smallest details.

Delivered with a 10-year warranty instead of the usual Armin Strom 5-year warranty, the new Armin Strom Mirrored Force Resonance First Edition ref. ST22-RF.75 has a price of CHF 58,000 / Euro 61,600 / US$ 59,000 which is an attractive price for an exclusive Haute Horlogerie timepiece at this level of complexity, craftsmanship and rarity. arminstrom.com