[s-cars] Bose head unit notes

Kevin Day kday at ultrameta.org
Mon Jul 19 22:27:10 EDT 2004

There seemed to be a bit of confusion in the archives as to whether the
stock Bose (Blaupunkt) head unit can be mated to aftermarket amps and 

For the record, the Audi/Bose Gamma CC unit in the Ur-S4 has fairly
standard (for car audio) line-level outputs.  I measured 1.8 Vrms 
maximum at the input to the rear amplifier.  For the measurement I
burned a 1 kHz sine wave at 0 dBfs onto a CD and turned the volume 
all the way up with the speakers disconnected.  Tone controls were flat.

I do not believe that the head unit is doing any equalization of the
signal.  I have it on good authority that the EQ in Bose systems of this
vintage is done in the amplifiers, using good old fashioned RLC circuits.  
A visual inspection of the amp PCBs seems to confirm this.  (There are 3
different amp part numbers, incidentally: LF RF and rear.)

In any event, after confirming that the output was normal 
I hooked up an aftermarket amp and a new pair of 6x9s in the back.  It
sounds pretty good, considering I haven't done the front yet.  

Anyone have words of wisdom to share regarding wiring up the front 
speakers to an amp in the trunk?  Wiring routes?  

'94 S4

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