Bose with aftermarket head unit, using factory amps?

Ben Swann benswann at
Fri Nov 21 08:54:44 PST 2008

Bernie - we are saying the same thing.  
If you don't mind pulling the door panels and rewiring things underdash, etc., then the
car can be rewired to use those speakers.   It is not simple or trivial.  One should be
able to wire up a system at the back of the stereo.  One should not havew to pull door
panels and dig in the trunk to rewire a speker that should have two wires.   I agree
there are some units that work fine as plug and play, but most don't, or at least in
reading the instructions do you want to take a risk of blowing a high-end head unit that
has instructions specifically stating - don't share the speaker ground.
Specifics:  each Bose speker has a sheilded twisted pair of wires -  the two conductors
are very small - like 24 guage and not suitable for carrrying sound.  furthermore, one
of these wires is a common bridge to the other three Bose speakers.  The power wires are
not a direct run to the speakers.  Instead they are used to trigger a relay to power the
amplifier.  You cant run sound through a relay!  
Like I said, I installed a kicka$$ Clarion system in this V8 quattro, but it required
complete rewiring of the car.  I think the JVC unit that was there before on the other
hand worked using adaptor which supported the use of a common speaker ground as the
stereo apparantly worked fine with this setup - I don't know because the wiring was
already hacked before I got to it sand the stereo inop.


From: Bernie Benz [mailto:b.benz at] 
Sent: Thursday, November 20, 2008 11:57 PM
To: Ben Swann
Cc: 200q20V mailing list
Subject: Re: Bose with aftermarket head unit, using factory amps?

On Nov 20, 2008, at 8:30 PM, Ben Swann wrote:

The Bose systems can only be wired to a head unit that uses common speaker ground - some
do and many newer don't as they have independent amplifier circuits for each of the
speakers. If you can find a unit that shares the ground for all the speakers then it
would be relatively easy.

I just installed a stereo in a V8 Quattro with a Clarion that had indepaendent amps per
channel and flating ground and had to completely rewired everything. None of the Bose
stuff was retained, although those speakers can be rewired directly to the speaker and
remove or bypass the amplifiers. This is fine if you don't mind removing the speakers
from the door and redoing them and removing the ones in the trunk. Still you need to run
the wires to them - that is the major PITA.

Not so. There are enough wires from the HU to the amps that connections need only be
moved around at the amps to eliminate the common speaker ground and bypass the amps.

Why on earth Audi let this type of wiring go into their cars is beyond me. It really
turns aftermarket stereo installation into a nightmare. You cam't even readily break out
the power wires for reuse as speker wires since they are relay control wires -
overengineered to obsolete.


[Date: Thu, 20 Nov 2008 06:57:08 -0800 
From: Bernie Benz <b.benz at> 
Subject: Re: Bose with aftermarket head unit, using factory amps? 
To: "Kenneth Keith" <auditude at> 
Cc: 200q20V mailing list <200q20v at> 
Message-ID: <A56FB50B-23BF-4172-A6A9-A32ED20057CF at> 
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed 

On Nov 19, 2008, at 9:14 PM, Kenneth Keith wrote: 
> Anyone interested in some brand new Bose speakers in case I convert to 
> a regular setup? The head unit apparently has some preset buttons 
> that are stuck down and they said they couldn't enter the security 
> code that was activated when I bought the car with a dead battery. If 
> I can't fix that or put in another free one, I'll put in an 
> aftermarket head unit which I don't think I can use with the amplified 
> Bose speakers (right?). 
You can drive the Bose speakers with an aftermarket head unit, BTDT. 
The easiest head unit to install is Blaupunkt, inasmuch as the connectors are plug and
play with the Audi harness, just two pins to move in the power connector. With a little
rewiring at the Bose amps you can use the Audi harness wiring to the speakers.

> I thought I would give the stock Bose system a try since I haven't had 
> a working setup before, and I think the station frequency display in 
> the instrument cluster (which I have to pull to repair an apparent 
> ground problem, btw) is pretty cool. My last 200q20v got totalled 
> before I could respond to the Bose recall postcard, so I never found 
> out what that's like (since it had aftermarket speakers in it when I 
> got it). 
> Cheers, 
> Kenneth] 

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