papachulo

I have ordered an aftermarket head unit and plan on doing a simple installation to save money and retain all of the factory wiring.

My plan is to connect the 3 pairs of pre-amp outputs from my aftermarket head-unit to the factory amplifier by cutting the RCA's and connecting them to the factory amplifiers FR+, FR-, FL+, FL-, RR+, RR-, RL+, RL-, SUB+, SUB-. This should give superior sound quality versus using the new head-units internal amplifier, and will retain functionality of the stock subwoofer.

Concerns:

For the amplifier inputs I will connect the RCA ground shield to the - and the signal wire to the +. This is a single-ended signal (Audio signal only present on the + line, the - line grounded). I am not sure but it seems like lexus uses a differential signal (Audio signal present on both + and -). This may, or may not be an issue.

The headunit I ordered gives 2V pre-amp outputs and I am unsure of the level coming into the factory amplifier.

Has anyone tried this before? Any suggestions?

gapxguy

You have an aftermarket headunit equipped with RCA's, I would use an aftermarket amp for two reasons:

1) Clarity in signal from RCA to RCA.

2) More power to the speakers.

Even a cheap 4 ch. amp will sound much better than the stock one.

papachulo

I am trying to keep the install as simple as possible by avoiding having to dig into the factory amplifier or replacing all the speakers.

I do not believe there would be any noticeable improvement in sound quality by using an aftermarket amplifier on the stock speakers.

I've done the whole car audio thing with my previous car and it is too addicting. I always wanted more power, or better sound quality. I'm trying to avoid getting sucked into that this time. My previous car did 145dB; it was cool when i was 17, but now I just have different tastes and the stock volume/sound quality is satisfactory to me.

gs-ireland

TRUST ME, IT IS NOT POSSIBLE!!!!!


The factory amp input only takes a single L&R input (2x2 wires) and 5 outputs (FR,FL,RR,RL,SUB (5x2 wire)).

I hope you did not connect your new radio's RCA's to the OUTPUT of the amp!



The big problem with the factory amp is that it has an integrated audio processor that adjusts the front/rear/sub controls INTERNALLY via the data lines from the radio.

I got my hands on the amp's service manual as I wanted to modify it to keep the 5 channel amp. I tried and failed in modifying the internals of the amp and it is not worth attempting. I cut my losses and bought 2 amps and mounted them each side of the sub.

Rich27

iTrader: (9)

I agree with the previous posters. I spent days trying to figure out the wiring diagram to hook up a aftermarket head unit and stock amp. It's just not worth it. If you want to get a aftermarket hu, get a amp with it.

I totally understand where you are coming from. I too got addicted with the audio system on my previous car. I wanted to stay stock and cheap on my current gs, what that didn't happen. Since I wanted a aftermarket hu, I had to go with a 6 channel amp. After that, I now have a full audio system with navi.

So either go all out or just stay stock. The modding bug will get you.

gapxguy

I did the opposite of what you're trying to do - factory HU with aftermarket amp. What you're trying to achieve is even more complicated. People try to gain RCA outputs from a factory HU while you're priledged with them. An $80 4 ch. amp will be a night and day difference from the stock one. And believe me, even with factory speakers, the extra power makes it sound so much better. Especially with Nakamichi speakers.

2FiVE8

i worked at a stereo shop for 3 years and i can tell you that the problem with trying to use the stock amp with an aftermarket head unit isnt just connecting the + and - of each of the speakers from the radio to the amp, its that you would need to find out which wire is the "turn-on" wire on the stock amp and sometimes it will only take a certain power outage...the easiest and the best way is like everyone else is saying and to buy an aftermarket 4 or 5 channel amp. you are however still going to have to remove the stock amp completly and find all the door speakers anyway to connect those to the stock amp