The main difference is in the suspension: originally we had a foam suspension, supposedly more linear in the midrange.
However, we changed later for a inverted rolled rubber, more linear in the bass, and with very little audible difference (if any...) in the midrange.
I have come across recently two pairs equipped with the foam suspension, and the photos speak for themselves...
If you are in possession of such a pair, don't dispair!
Our friends at www.audiovintage.fr have found three potential repairers in Europe.
I am publishing the corresponding links here:
http://www.public-adress.fr/th-prod-205 ... rleur.html
http://www.reparationhaut-parleur.com/p ... itures.htm
In The Netherlands:
http://www.speakerrepairshop.com/index. ... 15&lang=EN
We will have soon some feedback from the owner of a pair who is using this company to repair his. Stay tuned!If you are in France, I would be tempted to use the official Audax repairer, but obviously, I have not try any of them, so you are on your own, I'm afraid!