Refurbishing Avalon Ascent Mk 2


After 25 years of service my Avalon Ascent Mk 2 have started to distort especially with classical piano.  I have isolated the problem to both 2" aluminium-manganese mid drivers.  These, I believe, were built by MB Quart of Germany, now out of business and the part seems unavailable.

I would greatly appreciate any suggestions on how I could bring back these speakers to their former glory. Thanks.

franzschubert
If you can't get the original replacement  drivers I think it's time to go shopping  for new speakers.  But maybe there is something  wrong with both drivers that is repairable.  Why not remove them and investigate? 
If Avalon can't help you and they can't be fixed then you must upgrade.
Did you try different components? I had the same problem with my Thiel 3.6 speakers distorting certain solo piano notes and Thiel said they could rebuild the driver if I remove it and send it to them. However, I picked up an SACD player and the distortion did not appear when playing the same disc. Turns out it was a bad polypropylene cap in the analog board of my Theta Gen Va.
Yes I have tried multiple amps, preamps, DACs and cables.  The distortion remains.  It is only ameliorated when I disconnect the midrange drivers .... hence my conclusion that they are at fault.
Hi franzshubert,

Try placing very small pieces of Dynamat on the dustcap of the offending drivers. It may take several attempts to find the right spot but this may work. Worth a try.

Dave
Dave,
When you say "dust caps" are you referring to the cloth grill or the wire mesh protecting the drivers?
Normally, the dome in the center of the driver that protects the voice coil from dust and such.  I just looked at pic of your speakers and see that it has a large single dome like the mids in my Thiel CS5i's. In that case, try different locations on the dome. Be VERY careful, let the adhesive properties of the Dynamat backing do the work of holding it in place, do not press lest you dent the dome. Just lightly touch it to the dome material.
Hi Franz...

So the first obvious question is, have you reached out to Avalon? They may have replacements for you in stock.

Next, I don't hear about midranges going out very often. Double check to make sure it's not a crossover thing. Examine the crossover for two possible items:

1 - Burnt resistors
2 - Electrolytic caps (anywhere).

Replace either.

Best,

Erik
Erik has a great point.  I assumed that was done and no remedy was available.
Avalon seem to have no interest in supporting legacy systems they are a different company from the Charlie Hansen days but I can try again.

The crossovers are separate, potted in 50 pounds of epoxy so there is no access to individual components. 
You could always reach out to Charlie. 
I have through Ayre .... do you have his email ?
@franzschubert  Assuming that it really is the drivers, this might be something that Bill LeGall at Millersound (http://www.millersound.net/) would be able to help with.

Dick
He posts here as charles_hansen.  Maybe try a pm?

Thanks.  Will do.
Franz,

If Charles doesn't pan out, I second djohnson54's recommendation to contact Miller Sound. Excellent on refurbishing drivers.

Dave
I have. Thanks