The core factor is essentially a beat: that of the El Primero caliber. Launched in 1969 just as the Swiss watch industry was facing the quartz crisis, it could well have vanished a few years later. When production was halted in 1975, Charles Vermot secretly saved the blueprints, tools and components, hiding them in an attic at the Manufacture in Le Locle. This act enabled Zenith to revive the movement in 1984.
The El Primero caliber’s signature lies in its 5Hz frequency. As early as 1969, this frequency enabled the El Primero to measure tenths of a second and continues to embed Zenith within a precision-driven approach. Caliber El Primero 3620 powering the Chronomaster Solo Sport is derived from the El Primero 3600 chronograph movement and retains its iconic operating frequency.
The 5Hz challenge
Operating at 5Hz presents a considerable technical challenge. A higher frequency involves more vibrations per unit of time, meaning the escapement therefore works harder and all components involved in power transmission are subjected to greater stress. Special attention must therefore be paid to the durability of the mechanical components. Caliber 3620 is thus equipped with a silicon escapement prized for its lightness, its ability to minimize friction as well as its non-magnetic properties.
That still leaves the question of energy: a high-frequency watch consumes more energy than one operating at a more conventional rate. Zenith nevertheless manages to maintain a 60-hour power reserve, corresponding to an entirely reasonable degree of autonomy for a contemporary three-hand watch. This approach is complemented by the stop-seconds function which aligns with this design philosophy enabling the time to be set to the exact second when the crown is pulled out and the seconds hand is brought to a halt.
Frequency as a language
The next most eye-catching feature is the dial, for which Zenith has chosen ceramic: a material more commonly used for bezels or cases. The surface takes on a more mineral-like appearance and becomes the canvas for a visual identity based on high frequency.
This identity is defined by a new motif centered around a Z inclined at a 45° angle. The symbol references the Manufacture while surpassing mere decorative repetition. Through its tilt, density and regularity, it evokes a pulse, a vibration, a signal – like the rhythm of the caliber beating beneath the surface.
The motif extends all the way to the counterweight on the seconds hand. The signature thus leaves the dial and comes to life, an impression complemented by a shark-tooth-style minutes track designed like a sawtooth-wave.
Wristworn precision
Extending beyond the dial, the watch continues this pursuit of visual balance. Its 40mm stainless steel case features understated dimensions that are nonetheless sufficiently distinctive to assert the timepiece’s sporty character. The unidirectional rotating ceramic bezel – whose shape echoes the minutes track – along with the screw-down crown and the crown guards reinforce the impression of a versatile watch.
Water resistance to 20 ATM confirms this freedom of use, without turning the Solo Sport into a radical tool watch. The triple-link steel bracelet features the ZENCLASP™: a folding clasp enabling tool-free micro-adjustment in 2.5mm increments and a total 1mm extension.
Available in four versions – three with a date display, a sunburst white ceramic or polished black or brown dial, as well as a more radical date-free black version – the Chronomaster Solo Sport comes full circle with regards to inherent paradox. It is not a chronograph, yet it remains a true Chronomaster through its El Primero 3620 movement, its frequency and the way it infuses this high frequency into the very design of the watch.
Chronomaster Solo Sport
Case: Stainless steel
Size: 40mm
Caliber: Self-winding Manufacture El Primero Caliber 3620
Functions: Hours, minutes, central seconds, date
Dial: polished black ceramic with Zenith’s exclusive high-frequency pattern built around a repeated 45°-inclined Z motif
Bracelet: triple-link stainless steel bracelet with ZENCLASP™ folding clasp and integrated micro-adjustment system
