Am I just having bad tweeter luck?

[random_id]

I built two different 2-way full range speakers. One is a simple TL, and the other is a quasi ML-TL/ported speaker. Both use completly different drivers, crossover components, and crossover frequencies.
The problem is that within two weeks, I lost a tweeter in each pair of speakers. One tweeter is a Peerless 811815 rated at 100W RMS, and the other is a Morel MDT-20 rated at >100w RMS. There wasn't any pop or bang, just annoying frequency-centered distortion.

I have them hooked up to a new Yamaha reciever that pumps out 100W RMS per channel. I know it is not a "refernce" amp, but it seems pretty good. I also don't blast the music. The crossovers are both 2nd-order Linkwitz-Riley crossovers, with zobels on the woofers and switched zobels on the tweeters.

But the weird thing is that the tweeters aren't completely shoot. They just sound raspy at certain frequencies. Its the kind of thing that drives you nuts. On one song, you can't here anything wrong. On another, you go insane because of this tin-rasp-distortion.

I almost wish they were completely fried. Then I would just think I was an idiot. But how it is now, I am an insane idiot.

Any ideas please?

[sreten]

Its possible the voice coils are rubbing the magnets.

I've fixed a tweeter before by gently coaxing the voice coil
it back into shape at it had simply slightly warped out of round.

The more serious diagnosis is over heating and wires
having become detached from the coil and resonating
at certain frequencies or rubbing the magnets.
Not much to be done here I'm afraid.

sreten.