Frequency is one of several factors that help to predispose a watch towards a certain level of precision. In general, a higher frequency can improve the potential precision of a watch since the natural motion of the wrist is less likely to coincide with the natural frequency of the balance; this avoids the creation of constructive (amplitude gained) or destructive (amplitude lost) oscillation interference due to wrist movement.
In other words, a busy wrist that tends to move – for example – in 1.5hz jerks is likely to have a greater effect on a watch that operates at 2.5hz (18,000 vibration per hour) than a high-beat watch such as a Zenith El Primero caliber 400 at 5hz (36,000 VpH). Increasing the rate draws the balance even farther from the normal oscillation frequencies of the wrist. Some recent movements, including the Breguet caliber 574DR (10hz, 72,000 VpH) of the 7727 Classique Chronometrie operate at even higher rates. Montblanc released the Timewalker Chronograph with 360’000 Vph (50Hz). To put things into another perspective, a quartz movement vibrates at a frequency of 32,675 Hz.
Most Common Frequencies
- 18’000 VpH (2.5Hz)
- 21’600 VpH (3Hz)
- 28’800 VpH (4Hz)
- 36’000 VpH (5Hz)
These common frequencies are not the only ones found in watches. Taking high frequency to the next level, TAG Heuer released concept watches featuring a frequency of 3’600’000 VpH (500Hz) and 7’200’000 VpH (1,000 Hz). As frequency rises, you’ll see that traditional balance wheels are replaced.
The TAG Heuer Mikrotimer Flying 1000 (500Hz) places most of the balance mass on an aluminum plate while the Mikrogirder (1,000Hz) uses pivoted tension between two blades. The Mikrogirder tracks time to the nearest 2,000th of a second. The faster the frequency, the smoother the seconds hand sweeps.
Many brands choose to use silicon within the movement to minimize wear, lowering the friction while also helping provide higher frequencies. However, many other factors influence precision, and balance size is a major one. Consider the Kari Voutilainen caliber 28. It operates at a vintage-inspired 18,000 VpH, but the immense size of the balance helps to resist disruptions caused by undulations of the wrist.
Moreover, Voutilainen employs a free-sprung balance (without a shock-susceptible mobile adjuster), a dual direct-impulse escapement (for reduced frictional losses at impulse of the balance) and an overcoil hairspring (for resistance to gravity-induced timing changes).
Collectively, these refinements illustrate the vast scope of chronometric refinements and the danger of judging a timekeeper by rate alone.