While refurbishing the door trim panels on my new/old 2001 Grand Prix GT (see new/old post in Intro/Noob forum), I decided to replace the Bose door speakers with some Infinity speakers, and a pair of component Boston Acoustics tweeters leftover from the custom system in my old (now gone/totaled) Bonneville.
Like many who have gone before me and replaced the Bose stock speakers but retained the stock head unit and amplifier, I found the results to be predictably underwhelming. Despite being pretty low impedance, the volume level from the aftermarket speakers is considerably lower than the stock Bose speakers. That being said, it's also blaringly obvious that the aftermarket speakers are of considerably higher quality than the cheap paper Bose/stock speakers, and I believe I've got a solid plan for improving the audio experience.
Through lots of web research, I believe the quality and signal output level of the stock `01 head unit is actually quite good. So my plan is to route the front audio to an aftermarket amplifier. I have lots of leftover audio gear from my old Bonneville, including some excellent Alpine amplifiers.
Based on the wiring diagram for the stereo: https://dl.dropboxusercontent.com/u/...1/WIRING53.pdf
This is my plan:
In the trunk, where the wiring harness connects to the amp under the rear shelf panel, I plan to cut the following wires and put male/female spade terminals on the cut wires, so they can be reconnected or rerouted to the aftermarket amplifier:
Tan #511 LF+ at terminal B10
Dk Grn #1947 LF- at terminal B9
Lt Grn #512 RF+ at terminal B8
Lt Grn/Wht #1948 at terminal B7
I'll use those for the signal inputs to the aftermarket amp to drive the front speakers.
Tap pink wire #314 Radio On, and use for aftermarket amp turn-on.
I'll run separate battery power and ground wires to the amplier.
Then cut the following wires and put male/female spade terminals on the cut wires, so they can be reconnected or rerouted to the aftermarket amplifier:
Tan #201 to LF+ speaker at terminal A11
Gry #118 to LF- speaker at terminal A12
Lt Grn #200 RF+ speaker at terminal A9
Dk Grn #117 RF- speaker at terminal A10
I'll connect the aftermarket amplifier's speaker outputs to those wires going back out through the harness to the front door speakers.
At least for now, this will leave the rear speakers being driven by the stock amp under the rear shelf panel.
That's my plan. It cleverly re-uses the existing wiring harness to get the line-level signals from the head unit to the trunk, where the aftermarket amplifier will be mounted, and re-uses the existing wiring harness to get the speaker-level signals from the amplifier back to the door speakers.
There is an aftermarket device, the PAC AOEM-GM24 http://a.co/3civiab that appears to tap the line-level outputs, but I can't tell if it mates with the wiring harness connector at the under-rear-shelf amplifier, or if it mates with the wiring harness that plugs into the head unit in the dash, and it doesn't offer a tap into the wires that go to the speakers, as that device retains the existing connections between the rear-shelf stock amplifier and the speakers.
For what I'm planning, I think my plan to cut those select wires at the harness in the trunk is better, and my plan to put male/female spade terminals on the cut wires will be useful if I ever want to remove my aftermarket amplifier and re-connect the OEM amplifier.
Any opinions on this? Am I risking noises? I've gone over this pretty thoroughly, and if time and weather permits, may get started this weekend.