Avantadrive_Original

Hello, I'm not sure if this has been present here before, but I'm getting fed up so here goes.

My car, a 2003 A4 Avant with Bose stereo, completely stock. Ever since I can remember, the front driver's side speaker for mid/bass range has cut out at low volumes (1-10 or so) and cut back in when the stereo is turned up to 13 or so. The cutout is fairly subtle, but when it cuts back in it's a noticeable click and then the quality of sound of what you're listening to improves dramatically (because of the addition of another speaker). This happens every time, radio, CD, etc. I've taken it to the dealer twice to have it fixed, where they claimed to do so, but it did nothing.

Recently, I took the door panel off under the suspicion that a loose connection on the speaker might be touching the door metal causing a short, and found no such evidence to support that theory. I taped some things up to be safe, but it didn't fix anything. I also found a little water behind the speaker driver when I removed it from the door, which I removed, but did not fix anything and which i suspect is fairly normal given that the speaker is in the door.

At this point, I'm at a loss, and I believe the problem was even worse today when I got in the car and had no left channel AT ALL (including the rear) until I turned the radio up to nearly 20, at which point the left channel clicked back on and remained normal for the rest of the 1/2 hour drive. The problem doesn't *seem* to be at the door, so maybe it's the radio? I'm looking to the advice of the experts on this forum, because I'm sick of the Audi dealers and I'd much rather just get this damn thing fixed myself!

Also, as an aside, I do have a Blitzsafe adapter installed for my iPod. I don't believe this could be causing the problem, which occurs with the radio just as well, but if anyone advises to the contrary I'm all ears. Thanks!

MacSub

Well the only thing that is common to both left front and left rear is the head unit. The Bose amp is 4 channel so it is unlikely to fail on both left channels, (althogh I guess it's possible)
If you wanted to work out whether it's the HU or the amp, the easiest way would be to buy a standard ISO speaker harness and wire up the left front to a spare speaker, pull out the HU and plug it into the speaker connector on the back. On the Bose system this connector isn't used.
If ths addition cuts out in synch with the cabin speakers then it is the HU pre-amp probably, if it doesn't then it is the Bose amp or possibly a dry joint on the amp (which would explain why it's ok at higher volumes).

Avantadrive_Original

The entire left channel cutting out was very unusual, and has never happened before today. I followed you until you said the "dry joint" on the amp, and how that might be related to the speaker working at higher volumes... could you explain what that means? Thanks...

MacSub

that over time no longer makes a perfect connection (due to oxidisation etc). Although very common, it is really difficult to diagnose, but at higher volume or when the device has warmed up the dry joint can sometimes remake the connection as more current is available to the circuitry & the operating temp rises.
This type of problem can be cured by running a soldering iron over all the solder joints that have a wired connection to the PCB. It is unlikely to occur on the PCB itself as these are usually produced in clean rooms where oxidisation is unlikely to occur. Wiring looms are added later in the production line.

WishfulThinking

I'm not sure why it happens.

XP-Elwood

Had the same issue in my 2003 B6.

Took it to the dealer 2x, they said "it was a blown speaker" the first time and replaced it

The second time they could not reproduce it, so they wouldnt fix it.

Since then the car was totalled, so hopefully the speaker works now LOL