I've been looking at thread after thread about this, and still have a couple questions. I've got an 04 SE that I want to upgrade everything in. I'm going to replace the head unit, replace door speakers (not the rear subs though), and add an aftermarket amp.

I wanting to use Alpine KTP-445U for my amp. This is an amp the Alpine claims can run off the same power supply that the head unit. I don't plan on doing it that way, and is what I have a question about. Is it possible to remove the factory amp and use the wiring in that location to run the Alpine? I know I'd have to run a remote turn on wire, and new RCA's. Could I use the power and ground wires going to the factory amp for the Alpine. Also, could I use the speaker wires leaving to factory with the Alpine so I don't have to run new speaker wires?

Lastly, do people buy factory working head units, amps, disc changers, and all the 12 speakers?

Thanks,
Mike

 

Just out of curiosity, why do you want to replace the factory amp and speakers? That alpine amp will not power 12 speakers and the two subs. A head unit that has a 5 or 6v pre-out sounds pretty damn good going through the factory amp and speakers (the subs are lacking but thats a personal preference)
But to answer your question, yes you can use the factory amp power, ground and remote, along with the speaker inputs/outputs. You should not have to run any wires from the head unit to the amp.

 

Manual for that amp states it has a 15 amp fuse on it. The factory amp is on a 15 amp circuit, so you should be good with power and ground.

There is already a wire running from the stock radio to the amp that is used for remote turn on, so you should be good there.

45x4 RMS, would give you a healthy boost. The OEM amp is rated around 35 Watts max I believe, which means your only getting about 15 to 20 RMS (if that)


But, your issue is going to be the loss of all the other speakers. Your going to lose SPL. Not adding back in the bass drivers, which there are 4 spread around the truck, might make your sound seem hollow.

Another issue is going to be finding 2 way components to fit the front door that are not over $400.

The two front bottom door speakers are not on the same channel as the upper door speakers and tweeters.

You will be lucky to get a 4.5 coaxial speaker in the upper door location, and you will be severely lacking bass/mid bass without also doing something about the lower door bass drivers.

You will have to run pre-amp RCA cables from the aftermarket radio to the new amp, unless you want to use high level outputs, which would not be good in my opinion.

 

I took out the rear subs since they didn't do anything at all. You could bare hear them, and there were working best I could tell. I also wanted to put a full cooking area on the rear door, and they were in the way. The factory amp has way to high of a frequency cut-off and there is zero bass in the remaining speakers. I'm taking out the disc changer as well since I haven't listen to a CD in years. I plan on adding a new CD player with Bluetooth, and all that other good stuff. If I were to install the Alpine amp I would also replace all the door speakers with Polk DB 6-1/2 components. The amp should be just right for those speakers. I'll put the Alpine amp where the factory is, and my power inverter where the disc changer is.

 

If your going to put 6.5 components in the front door, then your going to have to do some speaker wiring. Could use factory wires going to the 6.5 in the lower door, connect your passive crossover, then go to the other speakers.

I think the stock speaker wire is 18ga, which should be ok for 45 watts.

Are the polks you want to out in 3 way or 2 way?

 

I think I should be able to use the wire for the 6-1/2 in the doors to connect the Poly crossover, and then use new wiring going to the new 6-1/2 and tweeter. I'm just going to have a 6-1/2 and tweeter in each door. So I think the Alpine would be just right to run the 2 sets of components. I assume I should still run a couple good set of RCA's from the head unit to the new amp though.

I'm still a little torn between the Poly db6501 (2 way) and the Fosgate P165-S (2 way).

 

agreed on the freq cutoff... I removed the rear subs and ran a separate powered sub. I have the doors with factory amp set at 100hz HPF with a mild slope. The aftermarket sub takes care of the remaining lower freq. I like it, everyone has their own taste though.
As for running RCA's, you dont have to unless you want to use some special cables for sound. Get the Metra 70-1786 harness and you can attach RCA pigtails to the other end of the input wires at the amp. Or just run 2 RCA cables. I dont like to run redundant wires if I dont have to

 

That should work!
poly db's? Do you mean Polks?

Polks are going to be the better SQ, fosgates are going to have more punch.

I would definitely suggest a good set of twisted pair RCAs between radio and amp.

I would love for you to report back and let us know how you think it sounds (which is always subjective)

Getting some mid on the top of the front doors would be awesome and make it sound fuller, but like we said, that would be some major $$$$$$$$$$$

 

Vette,

I have never tried the radio speaker wires to make low level RCA cables.

Wouldn't you worry about the lower level signal allowing interference?

I would think that putting in some twisted pair RCAs would greatly diminish the chance of any noise introduction.

 

Vette,

Another question for you. Since you are familiar with the Mentra wiring harnesses, do you know if they make one that would connect to the harness that plugs into the OEM amplifier?

That would keep him and others from having to cut any factory wiring.