A6 Stereo problem/question. please help!!!

[djneils98]

Hi all - new to the forum and need some ICE advice!

How do I find out what kind of stereo amplification system is in my 2000 A6 Avant 2.4?
It has a factory sub in the rhd of the boot and a concert rad/cassette (no CD) but I need to know if it is a BOSE fully amplified or half-amplified (rear only) setup.

I have had a new head unit fitted and i'm getting an engine related buzzing through the speakers (goes when engine is off)
The adaptor I have on it is a Maystar one and i'm thinking this could be the problem.
I've found some different ones on a kenwood website here-halfway down but there are 2 types - one for fully amped BOSE systems and one for half-amped ones.

thanks in advance guys.

[Niall76]

The buzz you speak of sounds like an earthing problem?

Did the old unit do it as well? Have you checked to make sure that the new unit is definitely earthed properly?

[djneils98]

thanks for the advice - i'll look into it - the old unit was fine. Maybe the fitter has done a poor job of the connection. On the maystar connector kit there was a wire that they were unsure about where to connect it. Perhaps thats the issue.
Is there an easy way to check the earthing? with a multimeter or similar?
thanks again

[Froggy]

Check to see if any of the speaker wires are directly connected or not to the new head unit. A Bose equipped car has no speaker wiring at the head unit, it's all done at pre-amp level.

Normally your speakers will say Bose on them if you have the fully amplified system.

[AJO]

This is a simple one....

i will reply on my lunch break

[AJO]

Right im back...

First
You would know if your stereo was BOSE or not, it would say BOSE on all the speaker grills and also when you turn the standard head unit on. if it doesent then its standard Audi equipment.

Second
Is the inteference coming from just the rear or the front also? at a guess i would say just the rear and id also guess your car only has half amped system like mine. Unplug the amp in the boot (big red plug) and see if the front speakers stop working? if its just the rears and the sub you know you have a half amped system.

Now providing you have a rear amped system only this is what the problem is. I know this due to having the same problem on my 2.4 A6.

The adapter you need for the rear amped audi system is the PC9-401

Standard System
The standard concert headunit runs only the front speakers, the rear speakers are amped up and so is the sub. they run at the following powers:

Front 2 x 15W straight of the head unit
Rear 2 x 25W off the amp in the rear
Sub 1 x 80W off the amp in the rear

by upgrading the head unit (probably 4 x 50W) you have had the following effect:

Front 2 x 50W straight off the head unit
Rear 2 x 50W which then runs to the Audi amp and reduced to 2 x 25W
Sub 1 x 80W off the amp in the rear

The factory amp is lowering the signal to the speakers which is where your interference is coming from.

What you need to do

1/ remove the plastic inner sills that run down the length of the car
2/ remove the lower part of the back bench so you can pull the carpet up
3/ pull the carpet back to reveal the wiring looms near both rear doors
4/ Find the loom thats got two wires taped up (its held down with duct tape)
5/ unplug the Audi amp in the boot and turn your stereo off.
6/ Cut these two wires to each door.
7/ run new speaker wires from the rear outputs on the headunit along the sills
8/ connect the new wires into the wires you have just cut coming out of the doors
9/ tape up the old wires coming from the Audi amp
10/ plug in the audi amp that now just runs the sub
11/ replace all the trim/carept and seats
12/ enjoy your stereo that now runs at 4 x 50W with an 80W sub.

[djneils98]

The adapter you need for the rear amped audi system is the PC9-401

thanks for that info
my stereo has a pre amp out - do you think PC9-404 might be more suitable??

also - I might want to put the factory headunit back at some stage - is there a way of losing the interference without cutting and adding wires?
thanks again, Neil

also - system doesn't seem to be Bose. I just disconnected the sub in the boot and the noise isn't coming through the front speakers just the rear.
So it looks like I have a half amplified non-bose system
The maystar adaptor the shop used had no phono leads on it - i'm guessing its the wrong adaptor and there's too much signal going to the cars amplified rears?
The head unit is a Pioneer DEH P55BT and seems to have a preamp out connection so maybe the PC9-404 would do the job properly?

[AJO]

you have the same system as me....

try what i said above.... try connecting the rear door speakers to the head unit directly

[AJO]

i garantee the interference is coming from the factory Audi amp. bypassing it solved the problem for me and it took half an hour max!