Hamilton Petite Seconde – Part 2

ETA A07 231

 I mentioned in my original post that this watch uses and ETA movment. What I did not mention is that it uses a new ETA A07 231 movement.

This fairly new movement is used on watches like the Longines Master Collection Chrono and in some Chopard models.

Some technical details on thise movement are:

Frequency 28’800 A/h
ø 16½’’’ – 36.60 mm
Height 7.90 mm
Winding Automatic
Power reserve 46 hours
Accuracy – 5 +15 sec./day
Base calibre ETA A07 231
Jewels 25

The ETA A07 231 is being touted by some as a replacement for the Valjoux 7750. As blogged about recently, the 7750 is a fine and efficient winding mechanism. It has a reputation for being fairly robust with solid time-keeping quality but the design is more than 40 years old.

The following are edited from a forum that listed some attributes of this movement:

A) the increase to 46 hour power reserve means several things.
First, you have more power to play with when adding complications; second, the power curve of the spring will also have a longer linear portion, which invariably increases accuracy.

B) As can be seen from this picture, there’s room on the movement for the watchmaker to get down and funky with. Adding a swan-neck regulator on a 7750 can be done, but it’s tight, and on the A07 you’ve simply got more real estate to work with. Adding customized work is simply easier with a larger movement.

C) ETA is doing its horological homework and knows that watchmakers are having difficulties selling $10k watches with the “same” work as a $2k watch, all other things being equal. Making the base movement a tad larger means that it will run more smoothly, since you are increase the mass of the moving parts.

Looks like one more reason to get that Hamilton 🙂

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