Dahlquist DQ10 issues


I have a set of Dahlquist DQ-10 that sound great, but if I listen at moderate volume for 30 minutes or so the right one begins to fail. It almost sounds like a completely blown speaker.  when I turn the system off and go to use it again later, it seems fine. If I listen at lower volumes, it seems to work just fine for as long as I want.

I thought perhaps I had an amplifier issue, so I tested by listening until I started to hear the failure, then replacing with another speaker and it was fine (I will hook up to a different amplifier as well, but I’m fairly confident it’s the speaker).

is it possible there are components in the speaker that are overheating that are causing an issue?  i’ve never had symptoms like this with any other speakers.
jleluga
"...so I tested by listening until I started to hear the failure...".                                                      Knowing how that, "failure" sounds would be most advantageous, to anyone attempting a diagnosis.      ie: A dead, complete speaker system (bad connection), rattling lows (surrounds & rubbing VC), highs gone (possibilities mentioned above), etc.

After a bit of trial and error, I've concluded it was a power amp issue after all.  I recently moved don't have these hooked up at the moment, but I will look for some greater clean power when I get set up again.