Avalon Acoustics?

They make a good speaker, however they use mostly Acuton diamond and ceramic midrange drivers made to their specifications. The bad news is  if you need to replace any drivers  they have to be purchased from Avalon and their pricing is extremely high. Got abused once and will never do that again.

Call me a skeptic but I am hesitant to believe that the drivers are made to spec.  I do see wood spacers and ferrules which I can understand for mounting purposes.  They addressed the leaking goo syndrome that plagued the Eidolons and Ascendants appropriately I think.  

I agree with you in regard to their drivers not made to spec. I purchased new mid range drivers from them and they were  at least 1/4 “ higher in overall thickness and the wire attaching device was reversed in terms of polarity compared to the original one it replaced. I think they sold me knock off. 

Manufacturers End of life drivers a lot of times. And speaker makers have no choice but to source new ones.  Are you talking about the C90-6-079 (vs the old 078) mid or the D20N6-31 tweeter?
if they use a 12dB per octave crossover I am certain they’d have to reverse the polarity and notate that the red dot.  

Samgar2 If your replacement mid is 1/4” higher then there would be trouble mounting into the cabinet. 
Note the black goo they use to get the back of the driver to mount flush against the supporting stud inside the cabinet.  If the new mid is indeed thicker it would spread the goo all over the place causing a mess.