^^ it sounded like a driver that was being pushed. Very well could have been the amp, it was only one channel of a Peavey though and I don't remember if DDT was lit up or not. I also don't remember if I had to stop because of the circuit breaker (in wall) or my own choice.
Now that I think about it the audible distress could have been gone by 40 hz.
The sweeps were from 0hz up and the most teeth gritting moments were the last couple of tests down low. You know when REW first starts cranking the tone?
At levels like that it reminds me of an old machine starting up. Slow and iffy until it gets moving...
It's been a while since I ran the test and I didn't take any notes or spend much time on it.
I do know the driver will travel a full 2" before the bottom spider to pole joint hits the top plate, and that has not happen in any test I've done since installed in their boxes.
No bad sounds from the drivers themselves.