A Little Potted History Of The Memovox & My Recently Acquired Cal 911

Not long ago I picked up this 1967 LeCoultre Memovox, cal 911, recently serviced by Zaf Basha. (Coincidentally, this is also a birth year watch for me although I didn't realise it when I bought it.) So, I thought it deserved a little write up and, of course, a few pictures.

A Bit of History
The Memovox was developed in 1949, following the development of wrist alarms by other manufacturers which since the first one in 1914 had been beset by problems. The first JLC Memovox was the manual wind cal 489 & was available to the public from 1951. Cal 489 was in production between 1950 & 1958. There are plenty of different case materials, dial furniture and sizes, but they al have the characteristic double crown arrangement. The bottom crown is a traditional winder and time setter. The top crown winds and sets the alarm time.

[Edit: Cal 489 was available in both shock protected (Parachoc) and non shock protected versions. The shock protected versions being classified as P489.]

In 1953, cal 814 was introduced as an iteration on cal 489 - with design changes that were probably introduced to facilitate better mass production. [Edit: Cal 814 was also produced in a P814 version, as well as a K814 version (designating the alternative Kif shock protection). In between cal 489 & cal 814, 2000 transitional movements designated cal 601 were made.]

Cal 814 was produced until 1964, when it was replaced by cal 910 (non-date) and cal 911 (date version). These were produced until 1979 in large numbers - 75,000 cal 910/911's were made in total. These were all manual wind movements. [Edit: With the 910/911 movements, only the Kif shock protection system was used & the use of the K designation was dropped - although I'm not sure exactly when that was. You can see on my watch below that it still carries the K911 designation.]

My Example
This particular watch has a serial no dating it to 1967 & is in a stainless case with a slightly unusual 14k solid gold bezel which adds a bit of jazz & light reflectivity to the case. It has a diameter of 35mm excl crown(s) and is 41mm lug to lug & a smoke grey dial which is showing some patination.




Bumpers
From 1956, JLC also produced automatic versions of the Memovox starting with the bumper cal 815 (from 1956-1966) which was a non-date & a date version as cal 825 (from 1959 to 1969). Approx 84,000 of these movements were made. The engineering problem these had to cope with was that the alarm post obstructed the rotor, so some redesign of the post and rotor was needed to allow both functions to exist in the same movement. [Edit: Both the 815 and 825 were also available as P815/P825 and K815/K825 variants.]

The most famous use of these two movements was in the highly collectible and expensive divers watches. The 200m rated Deep Sea used the cal 815 and was produced between 1959 and 1961, with only 950 watches produced. The 42mm Polaris used both the alarm complication and JLC's super compressor technology, which was a precursor to today's Master Compressor watches. The Polaris used the cal 825 movement and was tested to 600m. It was produced from 1965 to 1969. Trying to find one of these for under £20k now is quite a challenge...

Fully Automatic Versions / The Speedbeat
A full bi-directional rotor version appeared in 1969, being cal 916 (over 32,000 movements produced until 1978). [Edit: It was produced as a Kif protected mechanism only & the K designation was not used. I haven't seen one myself, so does anyone have a 916 they can post a picture of to confirm that ?]

The 916 was a date version movement, which required a redesign of the alarm mechanism to allow the rotor to swing freely through 360 degrees. It also ran at 28,800 beats p/hour, compared to the 18,000 beats of all the previous calibres and is often called the Speedbeat, for obvious reasons. This movement developed into cal 919, then cal 918 - which was still used up to 2005 in the Master Compressor series. Cal 918 might have been used a bit longer, but I don't have the catalogues between 2006-2009 to check ! The current MC Memovox is the "Tribute to Deep Sea" which uses a cal 956 and is a lovely update to the original and rare 1959-61 Deep Sea model.

Most versions of the Speedbeat are afflicted by 70's style cases whose designs haven't stood the test of time (and so aren't very sought after), but there are some in classic Memovox style cases which are very attractive. These can typically be identified by the classic styling, a "JL" logo at the 9 o'clock position & by the "Speedbeat" legend on the caseback - if anyone wants to get rid of one of these let me know 😀

Thanks for the great writeup of these iconic watches. 👍

When I was writing it, I knew I hadn't covered that. But I also wanted to go to bed 😀

As you asked so nicely, I 'll try to add it tonight 😝

Now edited to include the shock protection information 📖

This happens because the alarm release is triggered, and this allows the hammer (I think this is what you are calling the rotor) to release and flop around. Even my modern Master Compressor Memovox with the Cal. 918 does this:



The older watches tend to buzz more than ring, where the newer models have that old "school bell" tone to them:


Here is a video of a Cal. 814 I serviced a while back, showing the alarm being actuated and the hammer running:


The hammer strikes a post mounted to the case back to create the buzzing sound as shown in the photo above. On the modern version there is actually a gong inside the case back:



Big fan of the JLC alarm watches, and enjoy servicing the older models too, although parts can be difficult to find these days.

Cheers, Al

I would say the JLC is a bit softer....

And yes I am a fan of alarm watches, and some can be very simple like the Memovox movement, and some more complicated - this is a Benrus I serviced a while back:



Note the dot under the 12 o'clock marker - this is actually a window in the dial, and behind it there is a little red/white flag that indicates if the alarm is set or not. You will also notice there is only one crown, but the watch is manual wind for both the time and alarm mainsprings. Takes a little bit of thought to make that work with just one crown.

Here is the movement - it's a Langendorf Cal. 1241, and you will also see a slotted screw head sticking up on the balance cock. There is a cover that is screwed over the movement before it's put into the case, and this screw allows the user to adjust the rate of the watch without removing the cover and exposing the movement to any damage.



I made this video to show how all the functions of this little movement work for winding, setting, and triggering the alarm...


All cool stuff.

Cheers, Al