I got a 1996 A6 estate witha 2.6 motor when i have the radio on or play a CD there is a high pitched whistling noise from the speakers which rises and falls with the engine RPM. Also the voltmeter on the dash is reading just over 14 volts when running this is slightly more than it was doing before this noise started.
Also what sort of job is it to change the alternator on the 2.6.

 

a whistling noise comes from a bad ground. Check your resistance from your alternator to chassis ground should be less than .4ohms. Also check your speakers for any bad wires. I assume you still have the factory radio but if not. check that ground as well. Whistling noises usually come from bad stereo installs. Did you put a sub in? If so make sure the ground on the sub is less than a foot and a half, and the cable are the correct gauge for the watts the amp is putting out.

 

It has the orignal radio which has never been out the car the car is also running rough at times with the idle going to 1500 rpm then back to normal etc although it doesnt do it all the time and isnt doing it at the moment i have been told it could be the voltage regulator any thoughts

 

Did you replace the plugs?

 

when u say replace plugs are u on about the spark plugs or the one on the end of my tv cable? its off to have a new alternator done tomorrow, poxy german rubbish!!.....................been a bad day!

 

You don't need a new alternator! You would only need a new one if it isn't charging the battery proberly. 14 Volts means that its working just fine. You have a bad ground / isolation problem with your stereo. If you don't want to fix the stereo ground, then don't listen to it when you drive the car!

Also, you were asked if you had replaced the spark plugs. Some spark plugs and plug wires are sold without resistors. These can also create electrical noise that would effect your stereo.