Woofer Disttortion

[DavGoodlin]

That's an interesting one old coot 88. I have to try that.

I have a gently-used 1969 Zenith console with 10" woofers, and a spare pair of the same exact speakers from a similar console I scrapped. Which was used pretty hard by a friend of mine, it was his parent's Zenith and rocked many house parties etc.
I subbed in the hard-used speakers and there was a similar, but not always obvious, degradation in the sound. You can also feel the voice coil rub with your thumb*.
I assume the gently-used ones are not rubbing.

* Gently, using your thumb to push (in about 1/4 inch) on the coil, usually covered with a felt disc.
Any rubbing usually is transmitted to the cone as audible and you can feel it too.