Strange noise is coming from my audio speakers. It sounds just like a worn-out bearing, increasing the frequency of the noise with the rpms going up. The noise is most noticeable at idle and low rpms (up to 1200-1400) and I can hear it no matter if the audio system is turned on or off...

At the beginning I thought it's a bearing of some pulley under the hood...but when I get out of the car the sound is just disappearing. Then I heard it from the speakers, specially from those on the front doors.

Another thing - when I turn off the audio system there is no change in the volume of the noise... but when I turn off the A/C it disappears.

What could it be? Alernator, battery? I measured the voltage and it seems to be almost ok - on idle it's 12.8V, on engine turned off - 12.3V

P.S> Moderators, please change the topic of the thread... there it's been cut off when submitting!

 

should it not be 14.?volts at idle? there was a post on here a long time ago about a noise through the stereo, it could have been in the XK8 forum.

 

DONE

Graham

 

This could be a faulty Alternator Suppressor or it's harness:



It could also be the Alternator itself but this is less likely if it's charging properly.

Graham

 

Most vehicles have a capacitor to cut out engine noise through stereo, I'm assuming that's what GGG is referring to. Although, with my experience, the noise never happened with the stereo off. Maybe some power is still applied to the system on this vehicle?

 

Could be the suppressor or the alternator itself.

Your measured voltage at idle is too low-it should be around 14v, unless you've got all the electrical accessories switched on (headlamps, heater motor on maximum, heated rear windscreen switched on).

Raise the engine speed to around 1500rpm & then measure the voltage again-it should definately be around 14v at the higher engine speed. If it's still below 13v then there's a charging problem, or a connection problem in the wiring.

If the connections are all good, then it could be a faulty diode in the alternator. There are normally 6 diodes in the alternator main rectifier pack, plus another 3 for the rotor supply. If one of the main rectifier pack diodes fails, it will cause the charging current & voltage to fall-it will also allow a lot more 'ripple' voltage along the supply lines which could cause the noise you're hearing through the speakers.

 

Estilian - did you ever figure out this problem?? I have a similar issue that only happens in one of my speakers. I have the premium sound and I noticed that the right top dash speaker was "dead"... when I lifted it up I saw it was unplugged. After I plugged it in I got similar noises as you describe --- I swapped the front speakers and still had that same noise coming from the right top speaker. I now just keep it unplugged, but that's no fun... this weekend I am going to try to do some trouble-shooting. Any info would be greatly appreciated

 

Sounds like an earth/return wire problem to me...I'd check all the wiring, continuity and resistance of the speaker and audio ground circuits/wires....Allan

 

Maininahat98 beat me to it, but I 2nd that it sounds like a gnd problem.

 

Thanks! I hooked the speaker back up and here is the problem: Once I turn on the key, the speaker emits a high pitched whine from that one speaker only... when I start the car, that persistent whine is there, but I get another whine or squeal in addition that gets louder if I rev the car (again, only in that one speaker). ALSO, the sound quality out of that speaker is marginal at best. NOW, what would be the best way to track down this ground issue... I assume that both wires on the speaker go back to the amp in the trunk - or are they using the body as ground (I can't imagine)?? Where might this ground issue be and what would be the best approach to sort it out? It's weird since it is just that one speaker only... any and all input is greatly appreciated

and just to make it clear, this is a 2001 xk8 with the premium sound - I am posting in this forum because I was inquiring with the first poster...

 

This link may help you understand what you ar looking for.

Identifying and suppressing radio interference / 1 | How a Car Works

I think I would start with running a separate set of test wires to the speaker from the AMP, and eliminate the speaker wiring as the issue. If that stops the interference then you know there is a problem with the wiring to the speaker itself. or again if possible swap the speaker connections at the amp and see if the issue moves to the other speaker.

Hope it helps.


Steve

 

What Steve said.....shouldn't take very long at all to determine whether the speaker, wiring/ground or amp? is a t fault using Steve's suggestion. Best of luck, please let us know how you get on. Thanks, Allan