What is the frequency often heard in mechanical watches?

Q: What is the frequency of a mechanical watch?

　The term "frequency" is often seen in articles about mechanical watches. What is its role and meaning?

A: Value indicating the number of amplitudes of the balance

　This is a value that indicates the number of oscillations of the balance wheel, which is the heart of the watch. In theory, the higher the oscillation frequency, the more accurate a mechanical watch will be, but the shorter the power reserve and the more likely parts will wear out. Conversely, the lower the oscillation frequency, the longer the power reserve and the less likely parts will wear out, but the more likely it is that accuracy will be compromised.

Currently, 28,800 vibrations per hour (= 8 vibrations per second, 4Hz per second) is the mainstream.

　Older mechanical watches often had a frequency of 18,000 vibrations per hour, which means that the balance wheel vibrates 18,000 times per hour. Converting 18,000 vibrations per hour to seconds equals 5 vibrations per second. Converting this to Hz, which indicates the amplitude of left and right movement, gives half that, at 2.5 Hz per second.

　Currently, the frequency used by most watches is 28,800 vph (= 8 vph, 4 Hz/s). Taking into account accuracy, a long power reserve, and the durability of components, this is currently considered the optimal frequency for mass-produced wristwatches. However, some skilled manufacturers also produce models with higher frequencies, such as 36,000 vph or 72,000 vph.

　Advances in materials and machining precision have made parts less susceptible to wear than in the past, but because manufacturing costs are higher, models that boast high frequencies tend to be more expensive. Current high-frequency models include the following:

Main high vibration models

36,000 vibrations/hour (=36 vibrations/second, 18Hz/second)

Zenith "DeFi Inventor"

36,000 vibrations/hour (=20 vibrations/second, 10Hz/second)

Breguet "Classique Chronométrie 7727", Breguet "Type XXII 3880"

36,000 vibrations/hour (=16 vibrations/second, 8Hz/second)

Chopard "LUC 8HF Power Control"

36,000 vibrations/hour (=10 vibrations/second, 5Hz/second)

Grand Seiko models equipped with the "Cal. 9S85" and "Cal. 9S86," Zenith models equipped with the "El Primero," Parmigiani Fleurier "Tonda Chronor Anniversaire," Vacheron Constantin "Traditionnelle Twin Beat Perpetual Calendar" (in normal mode), and some De Bethune tourbillons.