Thread: installing custom audio system for friend

Hello Everybody,

I found this forum just like any other car enthusiast forum. The reason I came here was for some work i'm doing on a friends car which is a '98 Grand Prix GTP. He is paying me to do all of his audio work, so I took the job.

He wanted to install custom speakers first, so he bought 4 Orion speakers. Two 5 1/4" door speakers, and two 6x9 speakers which we originally thought drove the sound. Turns out that they make bass only, and its the 4" speakers beside them that do everything else. Well I installed those for him, and that was a 5 and a half hour job because of the seat removal. Well the speakers themselves are fine. Its the stock audio system that's screwing everything up. When a CD is played, sound only comes out of the front passenger speaker, and the bass is produced from the two 6x9's at the rear. The driver door speaker along with the two 4" speakers at the back only produce a tiny (like whisper quiet) amount of sound, and static can be heard from them when volume is changed. When normal AM/FM radio is played, the left rear 4" speaker starts making sound along with the passenger door, and the two others still have no sound. The 6x9 rear subs work all the time.

Now he bought a Sony Xplod 1200w amp, two Orion 10 or 12" subs, (I haven't been back to see that stuff yet,) and he is planning to get an aftermarket headunit. Since he bought all of that equipment, I want to rewire everything. I hear that there's a Delco amp behind the glovebox which is complete junk, so I might as well bypass that too. I don't like that stock headunit either.

I have good experience in car wiring, but I haven't done much car audio. I understand that some sort of heavy-fused wire will run from the battery to the amp which will be in the trunk, and a ground will have to be made. I did a little bit of research before finding this site, and I understand that the amp will power the subs, and the aftermarket headunit will power the speakers.

If somebody could clear this up for me, or refer me to a site that can help me, it would be greatly appreciated. Thanks.

it seems you have a good grasp of the basic concepts so far.

you might want to consider amps for the other speakers as well.

Well he doesn't really want to buy another amp, so i guess the Sony Xplod will power the Orion subs.

If he bought the mounting kit and harness for the aftermarket stereo, will that be enough to power the front speakers and rear deck 4" speakers? I looked at a wiring diagram, and it seems like the stock Delco amp behind the glovebox does absolutely nothing but amplify the signals. If i remove it, the four non-bass speakers will function the same right? I ask this so I can use the factory wiring for the front and rear speakers. (not including the 6x9 rear deck subs). If anyone could point anything out that seems wrong, it would be greatly appreciated.

Here's an update on what I got done today. My friend bought an amp installation kit thats rated for 1500 watts. The power wire is 4 gauge, which I ran through the firewall (hard job) and along the passenger side. The RCA and amp turn-on will run the driver side. Heres my question. I was reading an audio upgrade article on how a guy did his audio. He got his power for the amp from the power lead on top of the fusebox. He called it a remote 12V connection or something.

Link Here:
http://www.grandprix.net/upgrades/eng_pwr.jpg

Anyways, will that point be able to supply enough power for the amp? If not, I'll hook it directly to the battery. Thanks

Thats where the alternator drops off all of the power to the fuse box.

plenty of power there.

In fact its better you take it from there since it'll let you have a shorter run for less voltage drop/power loss.

Yup.

just make sure you cover it well so it doesnt rot.

If the strut towers rot, you'll need a new car. (or expensive body work which isn't worth it for a W body.)

Today i managed to get the amp mounted with the help of a friend, and I also got the power and grounds wired up. Tomorrow's job will be routing the RCA and amp turn-on. I was told today that the factory Delco amp can be used in conjunction with the aftermarket stereo. Is this true? If it is, it will cross off one more thing I have to do Thanks again

yes.

you just need to connect the pink wire to the remote wire from the new deck.

anyone know the signal flow from the delco amp? i pulled it out and tried connecting my speaker wires from my amp directly to the wires from the delco amp. i hadnt connected the rca's to the amp and all of a sudden i got sound out of my front speakers... which i thought was weird. does anyone have a wiring diagram or color code for the 98 grand prix gtp? i have a few basic ones but there are more wires than speakers and positives, ground, etc. i have 3 blue wires and 2 green so idk how it works but its driving me insane