Sit in a quiet room wearing one of these and, sooner or later, the watch interrupts you. Not with a buzz or a beep, but with a single clear note that arrives exactly as the hour turns, and then leaves. That is a sonnerie au passage — French for "strike in passing" — a mechanical chime that sounds the hour by itself, with nothing asked of the owner. It is one of the oldest ideas in watchmaking and, for most of the last century, one of the most expensive — which is why nearly every explainer about it is built around watches costing more than a car. This one isn't, because the mechanism behaves the same way in a $1,499.99 watch as it does in a five-figure Swiss one.
Lucky Harvey ZLS402-1 Sound of Nature Big Date, ocean blue — $1,499.99 at PrimeTimepiece.
What is a sonnerie au passage?
It is a striking watch that sounds one note automatically as each hour passes. You press nothing and set nothing. The movement quietly stores a little energy through the hour, releases a hammer against a gong at the top of it, then falls silent for another sixty minutes — one strike, every hour, whether anyone is listening or not.
The name does real work. Au passage, "in passing", tells you the chime happens as time goes by rather than when you ask for it. English-speaking collectors just say passing strike, and Chopard calls its version Strike One because that is literally the behaviour. Everything else in the striking family is defined by how far it departs from that single note.
How does the hour strike actually work?
A cam driven off the minute wheel turns once an hour. As the hour builds, that cam lifts a spring-loaded lever and stores tension in it. At the top of the hour the cam reaches its step, the lever is released, and a hammer snaps against a hardened gong anchored inside the case. The note rings out, the parts reset, and the cycle starts again.
- Timing. The strike train is geared to the minute wheel, so it always knows where the hour is. Nothing to set, no drift from the time display.
- Arming. A snail-shaped cam lifts the hammer lever over the final minutes, tensioning its spring. The watch arms itself.
- Release. At the hour the cam's profile drops away, the lever has nowhere left to rest, and the stored energy goes in one motion.
- The strike. The hammer hits the gong — usually a drawn wire or bar fixed at one end so the rest is free to vibrate — then lifts clear so it doesn't damp the note.
Two things follow. The energy comes from the same mainspring that runs the watch, so every strike costs a little reserve. And it is a mechanical event you can watch happen: on Lucky Harvey's hand-painted enamel snake, hammer and gong bracket sit dial-side in the open, beside the serpent's tongue.
ZLS501-2 enamel snake automaton, $2,399.99 — look to the lower right of the dial and you can see the hammer and gong bracket.
Is a sonnerie au passage a minute repeater?
No, and the gap is enormous. A minute repeater chimes on demand: you push a slide and the watch tells you the time in sound — hours on a low gong, quarters as a double note, remaining minutes on a high gong. To do that it must read the current time off racks and snails, encode it, and pace itself with a governor so the sequence doesn't run away.
A passing strike does a fraction of that job: one note, one moment, no encoding, no user input. The parts count and hand-finishing a repeater demands is why true repeaters from Breguet, Bulgari or Hermès sit in the high five and six figures while a passing strike can be built into a watch selling in the low four. Anyone offering you a "minute repeater" for four figures is selling an hour strike under the wrong name.
Where petite and grande sonnerie fit in
Both strike in passing too, just more of it. A petite sonnerie sounds hours and quarters without restating the hour at each quarter; a grande sonnerie does restate it, chiming hour plus quarters every fifteen minutes like a miniature grandfather clock, usually with a repeater on top. Those are grand complications. A single hourly strike is the family's front door. For the other complications sold at this end of the market, and what the rare tier actually costs, see our complications guide with a buyable example of each.
An alarm is something else again
Alarm watches such as the Vulcain Cricket or JLC Memovox are loud on purpose, run off a second barrel, and only sound once you have set a time and armed them. A sonnerie needs no instruction and marks a fact rather than a plan — nearer a ship's bell than your phone.
Can you turn the chime off?
Yes, and on any watch you would actually wear daily this is non-negotiable. Lucky Harvey's chiming models put a pusher on the case flank at four o'clock that toggles the strike between chime and silent, with a small indicator on the dial telling you which state you are in — so a glance, not guesswork, tells you whether the watch is about to speak. Step by step: how to turn the chime off, and whether silencing it does any harm.
The brand's own callout diagram: date-correction pusher above the crown, chime/silent switch below it, chime indication on the dial.
MeisterSinger follows the same logic on the Bell Hora, which also strikes in passing and also gives the owner a silencer. The function exists because an automatic hourly chime is charming at home and mortifying in a cinema, an exam hall or somebody else's wedding vows. Lucky Harvey advertises its silent mode as a world first for an automatic chiming watch — treat that as the brand's claim, but the feature itself is the one you want.
What makes one hour strike sound better than another?
Four things dominate: the gong, the case, the caseback and your wrist. A longer gong of harder alloy rings longer; how it is anchored decides whether the note sustains or thuds; the case either transmits that vibration or swallows it; and a soft strap against soft skin damps everything. None of it is magic and all of it is audible.
- Case material. Christopher Ward chose grade-5 titanium for the Bel Canto specifically because it improves the resonance and tone of the chime — a useful Swiss precedent, and a reason to hear Lucky Harvey's titanium chiming meteorite model next to the steel ones.
- Caseback. A thick, tightly screwed solid back is good for water resistance and less good for volume; the steel models use exactly that, so the note is intimate rather than loud.
- Gong mounting and damping. Anchored to the movement, the sound stays inside the watch; anchored to the case, the case becomes part of the instrument. Either way, a cuff over the crystal costs you volume.
So set expectations: every passing strike, at every price, is a quiet sound. Across a still room, lovely. On a city pavement, inaudible.
Solid, screwed caseback engraved with a soundwave and numbered out of 300 — secure and water-tight, but no help to the volume.
What does a sonnerie au passage cost?
Less than the internet thinks if you shop outside Switzerland, and a great deal more if you don't. The ladder runs from roughly $1,500 to the price of a house, with a wide empty stretch in the middle where almost nothing is offered:
- $1,499.99 — Lucky Harvey Sound of Nature Big Date, in hammered black, ocean blue, rose-gold brown or purple. 40 mm × 11.95 mm steel, sapphire crystal, big date, in limited runs of 300 pieces.
- $2,399.99 — the same complication in grade-5 titanium with a Muonionalusta meteorite dial, 40 mm × 10.95 mm, 98 g, 5 ATM, limited to 50 pieces.
- $3,795 — Christopher Ward Bel Canto, the watch that proved there was an audience for an affordable hour strike.
- €3,690 and up — MeisterSinger Bell Hora, single-hand and single-note.
- ~£20,000 — Chopard L.U.C Strike One, the same function in haute horlogerie dress.
- High five to six figures — true minute repeaters, for the sake of scale.
ZLS402-2 in hammered black, $1,499.99 — note the two pushers flanking the crown.
Is the movement in-house? The honest version
Partly — and the honest answer is more interesting than the marketing one. The striking module is Lucky Harvey's own. The base going train underneath is undisclosed; the brand refers to exclusive movement manufacturing suppliers, which is a way of saying the calibre is built around a bought-in architecture. Brand-stated figures for the CAL.LH003 are 28,800 vibrations per hour and roughly 40 hours of reserve, with product pages quoting up to about 42.
Before that sounds damning, look at the benchmark: the Bel Canto everybody praises is a Sellita SW200-1 base with Christopher Ward's own FS01 striking module on top — we set the two against each other in our Lucky Harvey versus Bel Canto comparison. Sourced base plus proprietary module is the architecture of accessible chiming — nobody builds a four-figure striking watch from a blank sheet. The useful question is not "in-house or not" but "whose module, and does it work". Lucky Harvey has also entered chiming and automaton pieces in the GPHG three years running: entries, not nominations or awards, but the watches have at least been put in front of the industry. Our brand guide covers the company itself.
What is a passing-strike watch like to live with?
Different from any other complication, because it makes a demand on the room and not only on you. Around 40 hours of reserve means a watch left off the wrist across a weekend needs rewinding, and every strike spends a little of that reserve. Wear it a week and you will know the silent pusher by feel.
Two practicalities. Servicing a striking module is specialist work, not a job for the nearest mall kiosk, so keep the papers and the box. And the brand was founded in 2021 — the company behind the chime — so there is no long service record to lean on — that unknown is the real price of being early to a category, and it deserves saying plainly. Lucky Harvey states a two-year international warranty; buying through a retailer with a clear returns process, a human answering emails and warranty handling in place hedges the rest.
Dressed up, it reads as a textured-dial sports watch — until the hour turns.
Which one should you start with?
If the point is to hear the complication, start with the steel Sound of Nature at $1,499.99: 40 mm, easy to wear, and the least money anyone is asking for a self-striking mechanical watch. The black and ocean blue versions share one movement and one silencer, and our hands-on review of the Sound of Nature covers how the ZLS402 wears day to day. Want a dial nobody else owns and the titanium meteorite at $2,399.99 is lighter, thinner and one-of-one by nature. Want the strike to move something and the enamel snake automaton costs the same — though its PrimeTimepiece page describes that chime as sounding on demand rather than in passing, so read the specifications closely if automatic hourly striking is the specific thing you want. For the wider field, see our round-up of chiming watches at the accessible end and our collectors' favourites.
ZLS413-2 in grade-5 titanium with a Muonionalusta meteorite dial, $2,399.99 — 98 g on the wrist.
Common questions about passing-strike watches
Is a passing strike the same thing as a minute repeater?
No. A repeater chimes on demand and encodes hours, quarters and minutes in different tones; a passing strike sounds one note automatically at the hour and encodes nothing. The repeater's racks, snails and governor are why it costs orders of magnitude more.
Can the chime be switched off?
On the Lucky Harvey chiming models, yes: a pusher at four o'clock toggles between chime and silent, with a small dial indicator showing the current state. An hourly strike you cannot silence is a watch you eventually stop wearing to work.
How loud is it?
Quiet. Across a still room it is clearly audible and rather lovely; in traffic, on a busy street or under a shirt cuff you will miss it. That is true of cheap and expensive striking watches alike, because a wristwatch gong is a few centimetres of metal, not a bell.
What is the least expensive way to own one?
At the time of writing, the Lucky Harvey Sound of Nature Big Date at $1,499.99 is the cheapest genuine automatic hour-striker we know of, against a Swiss entry point of $3,795 for the Christopher Ward Bel Canto. That gap is the reason this article exists.
Does striking affect timekeeping?
Not meaningfully, but it draws on the power reserve, because the hammer is armed by the same mainspring that runs the watch. On a roughly 40-hour movement that matters if you rotate watches: two days in a drawer and it needs winding and resetting before the next hour rings on time.
Where to hear one
The passing strike is the rare complication that is fun rather than merely impressive, and for the first time it can be had for four figures instead of five or six. Browse the Lucky Harvey collection at PrimeTimepiece to see the chiming and automaton models side by side, with full specifications and a straightforward returns process if the watch turns out not to be for you.