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[zirk]

So the Bose Amp must be High Impedance Pre Amp inputs then?, so what comes out of the Head Units in Bose Mode, surely it can’t be just a reduced volume speaker out that’s expecting to see a 2-4 Ohm, I suppose they could introduce some resistance in line with the Speaker Out (Bit like Headphone outputs on HiFi Amps), but then you would be re-amplifying an already amplified signal, it would work but wouldn’t have thought it would sound too clever let alone the noise figures?

I don’t know!, but would be interested to find out though, I’ll be playing around with a Bose upgrade shortly, so the more I could find out the better.

Chris

[petec]

Think I'll wait and see what conclusions you reach Chris before doing anything, my better half is expecting me to refit the bathroom before I start playing so you will probably have sorted it all out by the time I am ready to upgrade.

Just looking at the diagram in a Haynes manual 94-97 model, there are 2 configurations, one has HU connected directly to spks (standard setup), the other uses the same HU connectors but takes them via screened pair to "processor" and then on to spkrs, the processor also has outputs to 2 subs so this must be the Bose option.  

The fact that the HU to amp links are balanced pairs does support what has been said already, that they are probably just low level outputs from the power amps in the HU, the pin outs are certainly the same.

so it doesn't seem likely the outputs will be compatible with any aftermarket power amps as the latter always (?) have a grounded screen on inputs.


Pete

[petec]

suppose you could always build a balanced line driver stage to interface with an aftermarket power amp but it would probably make more sense to get an amp with high level inputs :-/

[Kevin Wood]

so what comes out of the Head Units in Bose Mode, surely it can’t be just a reduced volume speaker out that’s expecting to see a 2-4 Ohm

I didn't see anything in the CCR2006 to switch the outputs so my assumption is that it's just that. Maybe the Bose amp contains a load or maybe the amp is happy feeding a high impedance? I haven't dissected a Bose amp so I'm not sure.  :-/

The main issue is that it's balanced, whereas most amplifiers accept an unbbalanced input via a phono connector. The point I was trying to make is that you can't ground the -ve speaker wire and feed the positive wire into the phono input, as that will short one of the ouputs on the head unit power amplifier.

There are four things you could try:

1) Configure the head unit for Bose and feed the positive speaker connection into the amp's input and ground the outer of the amp input at the head unit. (effectively use one of the outputs as an unbalanced output), putting a load resistor across the speaker output of the head unit.

2) Configure the head unit for Bose and feed the balanced signal through a "ground breaker" for car audio installs (basically an audio transformer in a box) to convert it to an unbalanced signal referenced to ground.

3) Use the speaker outputs as is into an amp with speaker level inputs.

4) Break out the line level signals as I did.

All except option 4 leave the head unit power amplifiers in the signal path unless I've missed something when poking around in the CCR2006.

Kevin

[petec]

Kevin,

I agree with your 4 options and out of them option 4 does seem to be the only way to take the original output stage out of the loop.

I understood exactly what you were getting at with regard to amps in the 2006 having a balanced output which would prevent direct connection to another power amp input because it would ground one leg (and blow half the output stage) which is why I(only half jokingly) suggested knocking up an extra stage which would accept the balanced line input and output an unbalanced signal which can feed an external power amp.

On balance your route which involves picking up the unbalanced line level outputs from the cct board looks much simpler and neater and presumably works ok

[Kevin Wood]

Kevin,

I understood exactly what you were getting at...

Sorry. I didn't mean to imply otherwise.

On balance your route which involves picking up the unbalanced line level outputs from the cct board looks much simpler and neater and presumably works ok

Yes. It's been working really nicely. I'm starting to realise the FM tuner in the CCR2006 isn't too hot but the CD sounds very nice and it keeps the whole lot looking "bog standard" to the passer-by which is what I wanted.

Hope it goes well

Kevin

[petec]

Kevin

Sorry I didn't mean to imply that you meant to imply that I didn't understand what you were on about...Think thats right