Since the weekend, I've noticed an annoying buzz coming from one of my rear speakers. However it doesn't do it all the time, only on certain tracks with certain frequencies at louder than average volumes and even then sometimes it's fine. Would I be right in thinking that if I'd actually damaged the speaker, it would be quieter than normal and sound crappy all the time, and what I might have is just a vibration of trim (the Fabia seems a little bit "flimsy" in its rear corners compared to my old Leon) which is triggered by certain frequencies and/or other vibrations through the car? The other rear speaker seems fine and they're both aftermarket speakers (Vibe Slick 40s) with just a Kenwood headunit, no massive separate amp.

My other idea was that it could be a wiring problem, so I might take both speakers out and swap them over, see if the problem moves/stays/disappears.

Hi mate, I has similar in my Audi a3, try checking to see if ground is properly on / greased on the battery, funnily enough that was the problem for me!!!

I think it was down to loose trim after all. I noticed the other day that when I removed the string to drop my parcel shelf it didn't sit right, so I yanked it out and put it back in again. Sits right now and no more buzzing. Glad I found it before starting to tear bits apart and buying new speakers...

Argh. It's back.

I've checked the spec on my HU, 4 * 50W max. I've checked the spec on the 4" Vibe Slick 40 and they're showing up as 150W max. I'm assuming that both these figures are being given in RMS (as Kenwood and Vibe are both "proper" audio companies) rather than any other nonsense like PMPO. So I don't think the headunit should have been able to go loud enough to damage the speaker even if it was run at full volume constantly, which it obviously isn't?

It did occur to me that I had to remove my battery a few weeks back to try and replace my reverse light switch so obviously all the stereo settings would have been reset. So I think I need to try and work out Kenwood's god-awful menu system and put things back to how they should be :( I know there are various high-pass and low-pass filter settings on it somewhere, so maybe I just need to cut out v.low frequencies on the rear as the tiny speakers probably aren't handling those very well.

I'll check the ground if I get chance, but the fact that it only seems to be one speaker out of the four and I have no other electrical problems kind of leads me to believe it's probably not that. If I had a bad earth then I think I'd be seeing other symptoms (people used to complain of stuff like flickering interior lights and things like that, leading to the popularity of earth upgrade kits). Also get round to swapping the speakers left/right to see if the problem moves. Grateful for any other suggestions from people who know about car audio though!