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Discussion Starter #1
So ive currently got a JVC AVX740 double din headunit, which works with my GT's standard bose speakers/amp/sub.

These use the two RCA outputs from the back of the headunit (front and rear).

My headunit has a 3rd pre-out labelled 'subwoofer'

So, my plan is to wire an aftermarket amplifier to power two subwoofers.

How do i disable power going to the Bose amplifier? Which wire is it from the cars wiring at the back of the headunit?

Thanks
 

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The whole BOSE loom unplugs behind the glovebox. There are two plugs, disconnect them both and then join the two plugs left on your car's loom together.

Bear in mind the BOSE door speakers are a different Ohm rating to what is usual, make sure your aftermarket amp can safely run them. The amp inside the original Alfa headunit will not run them well, it causes it to overheat. By having the BOSE system plugged in this amp is switched off and the BOSE amp takes over.
 

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Discussion Starter #3
I still plan on running the bose speakers from the head unit. Only thing I want to chage is the subwoofer-replacing it with 2 aftermarket ones.
 

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I still plan on running the bose speakers from the head unit. Only thing I want to chage is the subwoofer-replacing it with 2 aftermarket ones.
All the bose speakers are run from the bose amp, removing power to it will kill all speakers. Running them from the head unit isn't really an option either as said above as the speakers are 2ohm not 4.
 

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I have this from a while back. The bugger is it does not say which are inputs and which are outputs - they are all together though one side = input - other side = output. In the 156 the woofer does not have an input signal - it takes it from the front / rear signals. So in my case I have to run a separate woofer signal cable to the back if I want separate woofer control
 

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All the bose speakers are run from the bose amp, removing power to it will kill all speakers. Running them from the head unit isn't really an option either as said above as the speakers are 2ohm not 4.
Yep, keep the JVC connected to the BOSE amp, and continue running the speakers this way.

Then just unplug the BOSE sub from the amp.

Next, install your new fused powerwire from the battery to your new amplifier, and add a ground wire. Extend the JVC's 'remote output' wire to trigger the new amp on/off. Add a length of RCA cables from the 'subwoofer output' to the new amp's audio input. Hook up your new subs, and you're up and running.

:)
 

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Discussion Starter #7
Excellent. That's how I was planning on doing it. I didn't realise though that the amp runs the speakers. I will just unplug the bose sub then.
 

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Extend the JVC's 'remote output' wire to trigger the new amp on/off. Add a length of RCA cables from the 'subwoofer output' to the new amp's audio input. Hook up your new subs, and you're up and running.

:)
Hi Shiny, can't he just piggy back the "enablement from radio" - PIN 6 at the back of the Bose. I did that for my 156... I agree to the rest - his new amp must be set to speaker (high) level input
 

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Hi Shiny, can't he just piggy back the "enablement from radio" - PIN 6 at the back of the Bose. I did that for my 156... I agree to the rest - his new amp must be set to speaker (high) level input
Yes, sounds like a good idea. Just need to find that right wire. :thumbs:
 
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