What’s the frequency? A guide to high-beat watches

Laura McCreddie-Doak

Do you know what frequency your watch has? Can you work out from listening to it whether it’s a 18,000 vph model or a more spry 28,800 model? Frequency isn’t something talked about much. It might be there on the specs, but it isn’t something people immediately start explaining when they show off their latest acquisition. Except if it’s a high-beat, that is. But what exactly does that mean, and is it something to brag about?

What is a high-beat watch?

Before we start comparing beats per hour, the first thing to cover is what frequency is when talking about watches. Here that word refers to the number of oscillations the regulating organ – that’s hairspring and balance wheel – performs in a second, which is measured in hertz or Hz, or in an hour, which is when you see a much larger number, such as 21,600 and the letters vph (vibrations per hour) or bph (beats per hour).

A single oscillation sees the balance move in one direction giving you the “tick”, then the other for the “tock”. Most watches run at between 2.5 and 4Hz, or 18,000 to 28,800 vph, with the latter number being the most popular. There are some exceptions. For example, some of the Omegas that contain a co-axial escapement, such as the current Seamaster 300M, beats at 25,200 vph, while at the other end of the scale Grönefeld makes a watch that runs at 1Hz. Generally speaking, the majority of watches sit within that bracket of 2.5Hz and 4Hz.

The frequency of a watch is often related to the size of the balance wheel. The larger the balance, the slower the oscillation, whereas a small balance makes things faster. That said, there are plenty of reasons why you’d want a large balance wheel, as this has its own benefits. From a purely aesthetic perspective, it also gives you the chance to admire the balance’s movement, rather than trying to follow the frenetic back and forth of a smaller wheel.

High-beat watches, as the name would suggest, are watches whose frequency is above 28,800 vph. The likes of Grand Seiko’s SLGH021, Longines’s Ultra-Chron and Zenith’s El Primero movement all come in at 36,000 vph or 5Hz. Audemars Piguet’s Jules Audemars Chronometer goes even higher at 43,200 vph or 6Hz, and Zenith’s Defy Inventor clocks in at an astounding 129,600 vph or 18Hz. The rule tends to be the higher the beat, the higher the price. Interestingly though, during the period of experimentation in the 1960s and 1970s, you could pick up a high-beat for under US$1,000, with Seiko being one of the main players in the space. These days, Seiko handed this technology over to Grand Seiko, but you can still pick up a Lord Marvel for around US$300 on pre-owned sites.

Does it make a difference to accuracy?

The answer is – it can. There are many things that contribute to the accuracy, or rather timekeeping stability, of a watch. Temperature, repeated shocks, and exposure to magnetism are all factors, and not just the frequency. How well the watch is made is also a factor. Having a balance operate at a higher frequency puts strain on the movement, requiring it to have more durable parts and better lubrication. In other words, a high-beat watch needs to be well-constructed in order to retain stability. One of the other ways in which having a high frequency helps to keep said frequency stable is impact recovery. High-beat watches recover faster from impact, so it takes less time to return to its functioning frequency.

However, high-beats also consume energy at a higher rate, meaning that the lever and escape wheel have more contact with each other. This increases the wear and tear on both parts and lowers the possible power reserve, which means there is more need for maintenance. The other issue is regulating the movement. The escape wheel needs a lower inertia to oscillate at a high rate, this means it has to be small, which makes it difficult to regulate.

Grand Seiko mitigates this problem with its Dual Impulse Escapement, which delivers energy both indirectly, like a traditional Swiss lever escapement from the palets, and directly from the balance via a star-shaped gear mounted on the balance itself, making the movement 20% more efficient.

High-beats in chronographs – the two escapement solution

High-frequency chronographs are an interesting intellectual proposition. If you have a watch that’s running at 5Hz, your chronograph can measure tenths of a second. But what if you want it to go higher, say, 100ths? To achieve this, you would have to fit the watch with a movement of 50Hz, which would severely deplete the power reserve.

Luckily there is a solution, one that Guy Semon innovated when he was TAG Heuer’s head of haute horlogerie back in 2011, and it was simple – use two escapements. In the Carrera Mikrograph 1/100th, the timing function ran off an escapement with a frequency of 4Hz or 28,800 vph, with a power reserve of 42 hours, while the chronograph escapement was 500Hz or 360,000 vph and had a power reserve of just 90 minutes if run continuously. This technology was adapted for the Zenith Defy 21, which has time keeping at 5Hz and its chronograph at 50Hz.

In many ways, buying a high-beat watch for its promise of improved accuracy is rather like buying a tourbillon for the same reasons. It’s not really the point. High frequencies are something to talk about, to geek out on. Whether or not they get those -/+ daily rates down is almost beside the point.