Buren and Duipuis Depraz


While the cal 11 - cal 14 movements had very limited commercial success over a fairly short lifespan, they were terribly important in the evolution of automatic chronographs and design idea explored by these watches are still the core of many watches today; they can in many cases trace their evolution back to0 these Cal 11 to Cal 14 watches movements built back int he 1960s.

cal_11
cal 11

The Caliber 11 is a 17-jewel modular chronograph measuring 31mm x 7.7mm. This modular architecture implies first a base movement, a micro-rotor automatic caliber made by Büren, in charge of the timekeeping part. Beating at 19,800 vibrations per hour, it boasted 42 hours of power reserve. Manufactured by Dépraz, the lever chronograph module is assembled on the backside of the base movement. This movement has a bi-compax display, with a 30-minute counter at 3 o’clock and a 12-hour counter at 9 o’clock – no running seconds sub-dial. The date is indicated at 6 o’clock. The unusual crown position, at 9 o’clock at the opposite of the chronograph pushers, is a signature feature of the movement.

Like most movements, the Calibre 11 has been optimized several times over its lifetime. As early as 1969, a barrel spring providing less torque is used. The date jump mechanism is adapted. The sliding pinion is changed and made in steel...

In 1971, a variant running at 21,600 vibrations per hour and named Calibre 12 is introduced. It becomes the main product of the calibre family. It uses a stronger barrel spring. The gear train and balance wheel are adapted. The chronograph hammer is modified to improve shock-resistance.


cal_12
cal 12

In 1971, a variant running at 21,600 vibrations per hour and named Calibre 12 is introduced. It becomes the main product of the calibre family. It uses a stronger barrel spring. The gear train and balance wheel are adapted. The chronograph hammer is modified to improve shock-resistance.


cal 13

The Calibre 13 is developed to integrate a small seconds indication in the periphery of the hour counter but will never be commercialized


cal_14
cal 14

In 1972, the Calibre 14 adds a GMT function and the Calibre 15 adds a small seconds to the Calibre 12, positioned at 10 o’clock, replacing the elapsed hours sub-counter.


cal_7740
cal 7740

Valjouz threw away the Buren microrotor bits, and used just the chrobnograph, adding a manual wind calling it Cal 7740. From this would would come two important things: 1) the Valjoux 77xx movement and 2) the Dupuis Depraz Chronograph module; both still around today.