The Eterna Calibre 1550, introduced in the early 1970s, represents a pivotal shift in Eterna’s legacy from mechanical innovation to electronic precision. Known as the Eterna-Sonic movement, it leverages Bulova’s patented tuning fork technology for exceptional accuracy, appealing to vintage enthusiasts who appreciate transitional horology. This quartz precursor offered smooth sweeping seconds and reliability that rivaled emerging electronic rivals.
Historical Context
Developed amid the quartz crisis, the 1550 powered luxury Eterna-Sonic models, often in 18ct gold cases around 35mm.
Licensed from Bulova, it marked Eterna’s foray into tuning fork regulation, blending Swiss finishing with American electronic patents.
Produced circa 1970-1975, these movements appear in cushion-case designs with date windows, now prized for their rarity and service challenges.
Technical Specifications
Type: Electronic tuning fork, battery-powered with electromagnetic regulation.
Jewels: 12, including shock-protected pivots on springs for durability.
Functions: Sweep seconds, quick-set date, hacking seconds (stops hand when crown pulled).
Diameter: Approximately 25-27mm, fitting slim dress watches.
Frequency: 360Hz tuning fork (high for era, ensuring ±1 second/day accuracy).
Height: Ultra-thin profile under 4mm, enabling elegant cases.
Decoration: Côtes de Genève on bridges, high-polish finishes typical of Eterna quality.
For any Watch Spare Parts inquiry, Email us for rate and availability: [email protected]
Watch Parts Enquiry
* If you are unable to fill out any of the required information fields, please type “N/A”.
Stem, Crown, Hands & Spares might be available for this movement.
Email us for rate and availability: [email protected]
Mobile/WhatsApp: +91- 9841 360 340