Car Stereos: 03 tahoe hooking amp to factory unit, hook ups, rca outputs

Question
I just bought a mtx monoblock amp  and subs , I want to keep my factory head unit ,truck came factory with bose ,I want some pointers on installing an amp to the exsisting head unit which is a six disc changer, and will i need any special connector .ihave s set of rca that have the ends cut off on one side i guess theres some wires on factory cd player to wire into ,since there are no rca hook ups ,I want to maintain the sound i have now plus what the subs will add. How do I do this? thanks Thomas

Answer
Hi Thomas,

There are a few different ways to get the results you're looking for.

Your best option, in my opinion, is to pick up a device called the PAC AOEM-GM24.  This is an adapter made specifically to connect an after-market amplifier in vehicles like yours.  The biggest advantage in your application is that it's completely plug-and-play; you just unplug the factory radio, plug the adapter into the radio and plug the factory radio plug into the adapter.  You'll get RCA outputs that you can use for your amplifier's inputs, and a switched remote turn-on voltage for your amplifier's remote terminal.  No wire cutting or splicing is required.

The AOEM-GM24 is available from a variety of online sources for around $50.

Another option is to use a conventional line-out converter, and connect it to the factory rear speaker wiring.  In this case, you wouldn't make your connections behind the radio; the outputs behind the radio are low-level, and won't work very well with a line-out converter.  You need to tap the wires between the factory amplifier (probably located behind the glove box) and the speakers.  An easy spot to find the speaker wiring would be at the bases of the "B" pillars, with the wiring that runs into the rear doors.  Typically the two factory speaker wires would be twisted together, and the wire colors would be dark brown (+) and yellow (-) on the left, and dark blue (+) and light blue (-) on the right.  You'd need to extend the input wires on the line out converter, and splice them into the factory wiring on each side.  This will give you an RCA output that you can use for your amplifier.  Some line-out converters include a signal-sensing remote turn-on output; otherwise you'd need to find a key-switched voltage source for your amp's remote connection.

You can try simply splicing your cut RCA cables into the low-level signal wiring between the head unit and the factory amplifier.  I don't have information on wire colors for these.  According to my information, the pin locations for the signal wires should be as follows:

Left rear (+)  B8
Left rear (-)  B9
Right rear (+) A11
Right rear (-) A10

I can't predict how this type of setup will work out, however.  Bose audio packages often use a type of low-level signal system that doesn't translate well to the common-ground, single-ended inputs used on after-market amplifiers.  You might find that you get an unacceptable level of noise in they system, or the signal level might not match well with your amplifier's inputs.  One advantage to using an interface device like the AOEM-GM24 or a typical line-out converter is that they'll usually include the ability to adjust the output level through the RCA's.   That makes it easier to match your amplifier's input range in a way that minimizes system noise.

One note:  whichever method you use to supply a signal to the amplifier, I'd suggest avoiding the front speaker outputs.  The GM head unit generates the warning chimes (door chime, seatbelt chime, etc) in your vehicle.  They play through the driver's door speaker.  If you tap into that signal source, you'll get warning chimes playing through your subs.

Hope this helps!

Brian