In article ,
The Natural Philosopher wrote:
If turning the speaker on its side tends to remove the nasty noises
I'd say the speaker suspension has sagged - quite common. What happens
then is the voice coil scrapes on a pole piece, making the noise. If
you can get inside it, invert the speaker.

If you can get at the speaker itself, try pushing the cone gently with
your fingers applying pressure all over. You can usually feel it
scraping if this is the problem.

I am afraid this is often the effective end of life for a bass unit.

plastic and rubber starts to rot ans do the cloth spiders, and no one
really recones stuff these days.

It depends. Spendor BC1 bass units sag like this without there being any
apparent damage. Inverting them every couple of years extends their life -
perhaps to infinity. Of course if the unit is rubbing because the voice
coil is distorted through overloading - or as you say through bits of the
unit actually rotting away, the only real fix might be replacement.

--
*What do you call a dinosaur with an extensive vocabulary? A thesaurus.*

Dave Plowman London SW
To e-mail, change noise into sound.