The history fits on a single page. Huygens observed the effect but lacked the mathematics to model it. The French clockmaker Antide Janvier built double-pendulum clocks exploiting the principle in the late eighteenth century. Abraham-Louis Breguet miniaturised paired oscillators into a handful of experimental pocket watches—perhaps three survive—and concluded that coupling depended on vibration through the movement plate rather than proximity or air turbulence. He even tested one in a vacuum. Then silence. For nearly two centuries, nobody touched it.

François-Paul Journe broke that silence in 2000 with the Chronomètre à Résonance, the first wristwatch to employ coupled oscillators without any mechanical linkage between them. Two independent balance wheels, two complete gear trains, one shared mainplate. No spring connecting them, no physical bridge—just micro-vibrations transmitted through rigid metal. The balances must be regulated within five seconds per day of each other for the effect to occur. If that sounds exacting, it is. Journe first attempted a resonance pocket watch in 1983. It took him seventeen years to get a wristwatch to work.

The 2020 revision, housing the calibre 1520, represents a significant mechanical evolution: a single barrel feeding a differential that splits energy equally to two going trains, each equipped with a remontoir d’égalité. The constant-force devices maintain stable amplitude for twenty-eight hours, addressing the original movement’s tendency toward amplitude decay as the power reserve diminished. It is sophisticated engineering in service of an essentially eighteenth-century idea. Journe is explicit about this lineage. His is the only wristwatch, he maintains, that uses “natural physical resonance without any mechanical transmission.” The purity is the point.

Armin Strom, from their manufacture in Biel, took a fundamentally different approach. Their patented clutch spring, introduced in 2016, is a flexible steel element connecting the hairspring studs of both balances—a deliberate, engineered coupling. Where Journe relies on the whisper of energy through a rigid plate, Armin Strom builds a dedicated channel. The clutch spring acts, in their language, as a “third oscillator,” absorbing excess energy from whichever balance is running ahead and feeding it to whichever is lagging. Synchronisation occurs within minutes, even if the balances’ daily rates differ by up to 250 seconds. That tolerance is fifty times wider than Journe’s. The system is robust, forgiving, and visually mesmerising—the sinuous spring oscillating between two exposed balances on the dial side invites sustained contemplation. Whether it constitutes resonance in the Breguet-Huygens tradition, or a different beast entirely, is the sort of question that generates heat in horological circles.

Beat Haldimann, working by hand in Thun without CNC machines, offered yet another architecture with his H2 Flying Resonance: two balance wheels sharing a coupling spring inside a single tourbillon cage, rotating at the centre of the dial. Vianney Halter pushed further still. His Deep Space Resonance places two acoustically coupled balances—hairsprings fixed to opposite sides of a shared wheel—inside a triple-axis tourbillon. No clutch spring, no mechanical linkage. Halter tested his prototype in a vacuum to confirm the coupling was structural, not aerodynamic. The watch is a conceptual proposition as much as a timekeeping instrument: one piece every three years, CHF 1.1 million, inspired by the 2016 detection of gravitational waves from colliding black holes. It exists at the frontier where horology becomes experimental physics made portable.

Here is the uncomfortable question that the trade press tends to avoid. Does any of this actually matter for timekeeping? A well-adjusted modern single-oscillator wristwatch can achieve a daily rate variation of a few seconds. The chronometric advantage of coupled oscillators—their supposed self-correcting property, where one balance compensates for disturbances to the other—has never been rigorously quantified by independent testing across the various systems. No comparative data exist in the public domain. The theoretical benefit is real in physics; whether it is meaningful on the wrist, at scales of a few seconds per day, remains an article of faith rather than demonstrated fact.

There is an even sharper terminological point. As a recent technical analysis in SJX Watches carefully argued, calling these “resonance watches” is, strictly speaking, a misnomer. In physics, resonance describes a system oscillating at greater amplitude when driven at its natural frequency. What these watches actually demonstrate is the synchronisation of coupled oscillators—each with its own motor source, merely locking in phase. The industry uses “resonance” because it is evocative and marketable. Precision of language has never been the luxury sector’s strongest suit.

So which approach represents genuine innovation, and which refines an old method? The answer depends on what you value. Journe’s system is the direct descendant of Breguet’s experiments—philosophically pure, historically grounded, and demanding extreme precision in manufacture and regulation. The 2020 remontoir upgrade is a brilliant engineering refinement of a centuries-old principle. Armin Strom’s clutch spring, by contrast, has no historical antecedent. It is a purpose-built mechanism that solves the fundamental fragility of natural coupling through modern engineering. If innovation means creating something with no precedent to address a known limitation, the clutch spring is the stronger claim. If innovation means pursuing an idea to its logical extreme without compromise, Journe’s refusal of mechanical linkage is the purer position. Halter, characteristically, transcends the debate entirely—his is watchmaking as cosmological metaphor.

What unites all of them is something the chronometric argument misses. Resonance—or coupled oscillation, if we are being rigorous—is one of the vanishingly few areas where independent watchmakers are conducting genuine mechanical research rather than elaborating on established complications. It is not a tourbillon, endlessly replicated. It is not a perpetual calendar, solved a century ago. It is a phenomenon still imperfectly understood at the scale of a wristwatch, still yielding different solutions from different minds, still capable of surprise. That may matter more than any rate variation measured in seconds per day.

About the Author

Sergio Galanti is an independent brand strategist and writer in the luxury watch industry. He is the editor of WatchDossier, a publication devoted to the cultural and philosophical undercurrents of modern horology.

No compensation or brand affiliation influenced this essay. Opinions are the author’s own.

Subscribe watchdossier.ch to receive more insights on luxury, craftsmanship, and collecting.

The orthodoxy is now so thoroughly established that it requires no argument, only repetition. A watch powered by a proprietary movement is understood to be, by its nature, superior to one animated by a purchased calibre. The reasoning, if one can call it that, is circular: the in-house movement is better because only serious manufacturers produce in-house movements, and they are serious manufacturers because they produce in-house movements. No external evidence disturbs this loop. The movement’s actual performance—its accuracy, its reliability, its serviceability, the elegance of its construction—is largely beside the point. What matters is origin. What matters is blood.

One recognises the structure. Every theology requires a hierarchy of purity. In mediaeval Christendom, relics were ranked by their proximity to the sacred body: a bone outranked a garment, which outranked a stone touched by a garment. The horological hierarchy operates identically. A fully proprietary movement outranks a movement with outsourced components, which outranks a base calibre with proprietary modifications, which outranks an unmodified ETA or Sellita, which occupies the doctrinal position of the unbaptised. That a modified ETA 2824 may keep better time than an in-house calibre designed last year and debugged incompletely is a heresy no collector forum is equipped to process.

The language surrounding manufacture status confirms the theological parallel. Brands do not simply announce that they have built a movement; they “achieve” manufacture status, as one achieves salvation. Press releases speak of “mastery,” “independence,” “sovereignty.” The watchmaker who designs his own escapement has not completed an engineering task. He has performed a sacrament. The collector, in turn, does not evaluate this achievement; he bears witness to it. He speaks of the movement with the reverence of a congregant describing the reliquary: he may never see it function, may understand nothing of its mechanics, but he knows, with the unshakeable certainty of faith, that it is holy.

What the doctrine requires, above all, is ignorance of the industrial reality it sanctifies. The Swiss watch industry is, and has always been, a collaborative manufacturing ecosystem. The Vallée de Joux and the Jura arc operate as a network of highly specialised suppliers—of mainsprings, balance wheels, jewels, cases, dials, hands, hairsprings—whose interrelations are so dense and so longstanding that the notion of pure self-sufficiency is less a fact than a founding myth. Even the most vertically integrated maisons purchase components. Even the most celebrated calibres contain elements fabricated elsewhere. But the doctrine of in-house does not accommodate nuance. It requires a binary: either the temple is pure, or it is profane.

The supply chain, accordingly, is treated as a sacred mystery—something that exists but must not be examined. A brand will proudly display its movement through a sapphire caseback while maintaining studied silence about which components were sourced, from whom, and under what arrangements. The collector does not ask. To ask would be to introduce empiricism into a system sustained by belief. It would be like requesting an audit of a miracle. The transaction depends precisely on the opacity: the watch is valuable because its movement is in-house; the movement is in-house because the brand says it is in-house; and the brand’s assertion is sufficient because the brand possesses the authority that in-house status confers. The serpent has its tail firmly in its mouth.

None of this is to argue that proprietary movement development is without merit. A company that invests in calibre design accumulates genuine expertise, earns genuine independence from supplier disruptions, and may produce genuine innovations—though this last outcome is considerably rarer than the marketing literature suggests. The objection is not to the practice but to the theology erected around it. When a manufacturing decision is elevated to a moral category, when the origin of a movement’s components determines not its functional quality but its spiritual worth, something other than engineering is being transacted. What is being transacted, quite precisely, is belief.

And belief, in luxury as in religion, is not incidental to the system. It is the system. The collector who pays a substantial premium for an in-house calibre over a demonstrably competent Sellita equivalent is not making an engineering assessment. He is paying an indulgence. He is affirming his membership in a community of the doctrinally correct. He is purchasing, along with the watch, the consoling certainty that he has chosen well—not by the vulgar standards of function, but by the higher standards of faith.

Voltaire observed that if God did not exist, it would be necessary to invent him. The watch industry, confronted with a market in which mechanical timekeeping is technologically obsolete, has understood this principle with exquisite clarity. If the in-house movement did not exist as a doctrine, it would be necessary—commercially necessary, existentially necessary—to invent it. It has been invented. And the faithful, as always, are the last to notice.

WatchDossier · Voltairian Series

About the Author

Sergio Galanti is an independent brand strategist and writer in the luxury watch industry. He is the editor of WatchDossier, a publication devoted to the cultural and philosophical undercurrents of modern horology.

No compensation or brand affiliation influenced this essay. Opinions are the author’s own.

Subscribe watchdossier.ch to receive more insights on luxury, craftsmanship, and collecting.

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