Re: Mystery A6/A4 speaker noises

[Elliott Potter <epotter@abraxis.com>]

This sounds like it's interference caused by the motors that move the
flaps that direct the air for the climate control.  Does it happen right
when you turn the car on?  Does it happen if you change the temp. on the
climate control more than 4 or 5 degrees?

I think it's because of poor power filtering/shielding in the speakers
with built-in amplifiers.

HTH

Elliott

> Thought I'd see if any other A6/A4 owners on the list are having this
> unusual occurrance.  My A6QW has the Bose system with factory CD changer.
> I have been noting an intermittent electronic sound (faint buzzes) that
> follows somewhat of a pattern coming over my audio system. It is unrelated
> to the music being played, and to whether I am listening to AM, FM,
> Cassette, or CD.  In fact, I recently discovered if I drive around long
> enough with the volume all the way down, I can hear the sequence of buzzes
> at the same volume, and the volume knob does not impact the volume of the
> buzzes.
> 
> The sound itself is a high pitched buzz that occurs in groups of
> approximately the same duration - a half second buzz and a second of
> silence repeated 10 - 20 times and often terminating with a longer buzz.
> It is at or near the threshold of hearing due to road noise underway,
> though now that I've pointed it out to my wife, she recognizes it as well.
> Its not very loud, mind you.  In fact, the first several times I heard it,
> it was between songs on CDs and I thought it was the very faint clicks and
> such that some discs have when they switch tracks.
> 
> Then I thought it was from my digital cellphone, a noise source discussed
> here on the list as well as in my Audi literature.  It occurs without the
> phone or power cord in the car however, so I ruled this source out.
> 
> Recently, I narrowed it down to the right front door speaker.  The stereo
> itself and that speaker otherwise play normally, with good quality sound
> for an OEM installation and no distortion.  If it were not for the fact
> that the sound occurs with or without volume, I'd suspect a bad speaker,
> but nothing else seems to be a problem with that speaker. The balance does
> not diminish or shift the sound away from that speaker.  This says it is a
> line level noise to my limited knowledge of electronics.
> 
> On a recent 30 hour straight through road trip alone in the car, I
> experimented with every conceivable combination of fan speed, cruise
> on/off, rear defrost on/off, lights on/off, etc and found nothing that
> changed or impacted the sound in any way.  Nada.
> 
> If any of you have this same stereo in your car, or have heard something
> like this before, I'd appreciate your input.  The last thing I want to do
> is have some hamfisted mechanic ripping the stereo out of the currently
> tight and rattle free dash to install another one under warranty.  Sorry
> about the length, but I wanted to answer all the questions I thought I
> would get in advance.
>