These informations were mostly gathered through my own experience, from watches I actually had in hands. They reflect what I observed and are not the holy truth. Page updated November, 20th 2024.
Text & Pictures : D. Broglin – Watch & Vintage
The Ultra-Chron has been introduced in 1967 to house the newly developed Longines 43x movement. This calibre was one of the first in the world to feature 36,000 beats per hour. Longines claimed that it was the most accurate movement on the market at that time. The first models, and until 1968, were all fitted with the 43x movement and from 1971 with the 664x /665x movement, which was similar to the 43x but beating at the rate of 28,800 bph.
The design
Cases
Most of the models had tonneau shaped cases, monobloc or with a screw back. However, there were more traditional round-shaped or pillow cases, a hexagonal one and and square one. There diametre were quite small, from 34 to 37 mm. The crown was Longines signed. The cases were made of stainless steel, plain 18k gold or were simply gold plated.
Dials and hands
In opposition to the claimed modernity of the high beat movements, the design of the dials were very classical, with the Longines logo at 12 and the Ultra-Chron logo at 6. The colours of the dials were classical as well, silver, champagne or more rarely black or blue. The date window (cal 431/6651) could be at 3 or at 4.
Bracelets / bands
Most models were equipped with a black leather band but stainless steel bracelets were also available. They were of milanaise type, with a Longines signed clasp.
The movements
There were only two movements available for the Ultra-Chron : firstly the 43x declined in several versions, always with 17 jewels and 36,000 bph : 430 (sweeping second), 431 (the most common one, with date display), 432 (no second hand), 433 (no second, with date). Some models were “Chronometer” marked.
Later in the production, the 43x calibre has been modified to become the 664x and 665x, with a lower beat rate (28,800). Several versions were available, with 17 jewels (6641, 6642) or 25 jewels (6651, 6652).
Some examples
Successors, reissue
In the middle of the 70’s, quartz movements were about to dominate the market and most of the brands invested more time and money into them. The Ultra-Chron and their sophisticated movements were abandoned for a while. Only in 2022 Longines relaunched the Ultra-Chron, with again a 36,000 bph movement (L836.6)