What can make a speaker vibrate (buzz)?

[RMutt]

The bass driver on one of my speakers is vibrating. Certain piano notes are the chief culprits. It does not happen all the time but certain frequencies or sounds result in a distinct buzz. The driver is 15inch and in a Goodmans Magister . I posted a thread a little while back on the repair of them when they were over driven at Christmas. I can't find the thread, but the repair involved sanding down the inside of the voice coil former which was scraping/jamming against the magnet. I thought the repair was successful but now this vibrating has started. When I push the cone there appears to be no scraping what so ever and it moves freely. Has anyone any ideas as to what could make the driver buzz?

[Puffin]

It sounds like the voice coil rubbing, which is what the repair you did previously was attempting to correct. Over time gravity can make the cones sag which causes voice coil rubbing. You could try turning the unit so that what is now the bottom is at the top to see if this makes any difference. If you think about how long they will have been in their current position.......

[struth]

I did that with a set of 12" ones and it solved the problem

[RMutt]

Thanks for the replies Rob and Grant. Sorry, I should have said I've tried turning it upside down. The obvious thing is rubbing. Is it possible for this to happen but to feel no rubbing or scraping when you push in the cone?

[struth]

usually you would feel something. doesnt have to be much. Drivers might just be old; happens with some really big uns. Geoff might be more help but is on hols at moment.

[RMutt]

Thanks Grant. Seems to be totally free when I push on it. Very frustrating as I thought I'd sorted it out with the repair. I wrecked both of them at Christmas but only one is playing up. I don't really want to open them up again.

[danilo]

Likely (clearly) the Overdriving did More damage than a rubbing voice coil, which was just the most obvious manifestation.
Buzzing is often from a tear// possibly where the voice coil former attaches to the Cone.
Rubber cement can be a reasonable repair, in the interim at least. to test/see IF that Is the problem.
Beyond that... You get to buy a recone

[Sherwood]

The bass driver on one of my speakers is vibrating. Certain piano notes are the chief culprits. It does not happen all the time but certain frequencies or sounds result in a distinct buzz. The driver is 15inch and in a Goodmans Magister . I posted a thread a little while back on the repair of them when they were over driven at Christmas. I can't find the thread, but the repair involved sanding down the inside of the voice coil former which was scraping/jamming against the magnet. I thought the repair was successful but now this vibrating has started. When I push the cone there appears to be no scraping what so ever and it moves freely. Has anyone any ideas as to what could make the driver buzz?

Been playing any Rimsky-Korsakov lately?

[walpurgis]

Geoff might be more help but is on hols at moment.

Geoff has popped in briefly. I'll have a chat with you about this in a few days when I have more time Andrew. I reckon there may be a solution.

[RMutt]

Thanks Danilo, Geoff and Geoff who kindly interrupted his holiday.