Mystery Distorted Tweeter - Bad from Factory?

[natebot88]

A few months ago I recapped both of my Polk Monitor 5b's with brand new Dayton MPT poly caps, (but not the 2 ohm, 5W resistor on each).
I also replaced the stock SL-2000 tweeters with brand new RD0-194 drop in replacements. They sound fantastic!

A few weeks ago I started noticing slight distortion in one tweeter. I confirmed the tweeter is damaged by swapping it to the other cabinet and noting that the distortion followed.

Measuring both tweeters with REW and UMIK-1 confirm that Fc (-3 dB) for both is bang on factory spec at ~1.1 kHz.
The amp is a Denon AVR-S750H at 75W / 8 ohm. Confirmed all good connections in the signal path.

I never played music too loud since installing these upgrades. Though I did kind of an ugly soldering job given a terrible, old soldering pen (it was all I had), there appear to be no cracked solder joints in the xover.

I will order a new tweeter if I know there is no flaw in my system that will blow out the new one (i.e., it was bad from the factory).
What could have caused the damage?? Could an improperly-adjusted preamp not compensating for EQ gain do it? (Less than 5 dB gain!)

 

[natebot88]

Following up almost a year later-- I found the solution! Something was rattling inside the tweeter.

I removed the tweeter from the speaker entirely. There were screws holding on the face place (which the dust cap is attached to), and I carefully removed that. There was a small paper O-ring inside that I reseated, and I gently blew some air from a Rocket Blower throughout the assembly to dislodge any contaminants. Good as new! No distortion at all anymore!