There’s really no other way of putting it — the Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar is the most exciting horological development this year and one of the most innovative of all time.

In the lead up to the launch, I keep telling people, it’s not just a new watch; it’s a new kind of watch. The Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar is the first watch in the world that allows you to switch between a high-frequency balance and a low-frequency balance, extending the power reserve by up to 65 days. To use an analogy, it’s equivalent to being able to change gears and optimise fuel consumption according to your needs.

Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar

Here’s some basic facts behind how that works. The mainspring barrel is the energy source in any watch movement, being a coiled spring that unwinds to provide energy to the balance so that your watch can actually keep time. This energy is released in intervals determined by the balance frequency. Energy is released 10 times per second in a 5Hz balance, 8 times per second in a 4Hz balance, 6 times per second in a 3Hz balance, and so on and so forth. As you can extrapolate from this, having a higher balance frequency means your mainspring drains at a faster rate, and having a low balance frequency means a longer power reserve.

Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar

Why don’t all watches run off low frequency balances for longer power reserves then? Because there are performance trade-offs. Low-frequency balances are more easily disrupted than high-frequency ones. You mess with the balance, you mess with chronometric performance. Not a good idea if you want your watch to actually, you know, keep good time.

The Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar can be switched between two modes — Active mode, which runs off a 5Hz balance, and Standby mode, which runs off a 1.2Hz balance. The Active mode is designed for everyday wear, and has four days of power reserve. This is already pretty major, since the most common 5Hz watch out there has like a two-day power reserve or something.

If you’re not going to wear the watch for a while, you can switch it (using the pusher at 8 o’clock) to Standby mode and set it aside. Frequency drops, power reserve extends. For the full 65 days of power reserve, wind the watch before setting it aside.

Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar

Okay, great, but why is the long power reserve so important? Because of the perpetual calendar, you guys! Perpetual calendars are so named because they keep track of the calendar without needing manual input to distinguish between short and long months, and take into account the extra day in a leap year. But let’s be real, the perpetual calendar is only as useful as its power reserve allows it to be. If you don’t wear it for a couple weeks, the next time you pick it up, you have to update all the calendar indications. First of all, nobody’s got time for that. Second of all, what would be the actual point of getting a perpetual calendar over a simple calendar?

Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar

With the Twin Beat system, you can wear the watch just six times a year, once every two months, and still have perfectly accurate calendar indications every time you strap it on. Do you see how major this is? The Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar is the closest thing to a perpetual calendar that actually works in perpetuity.

It is a watch that takes care of itself, and by doing so it takes care of you and your time. It’s incredible that no one ever made something like this before, and Vacheron Constantin deserves all the credit in the world for successfully developing this concept. It is a mechanical and philosophical triumph.

Now, stay tuned for a deep dive into the mechanical innovations involved in the making of this watch, because believe me, there are plenty. See you guys on the other side of SIHH.