Help: How do I tap oem wiring to get a RCA connector?

[SCoupe]

Before you say "get a line out coverter", I know what they are, they take an amplified speaker output. I do not want to use the amplified output, convert it back to a low level and then re-amplify it again.

I want to tap my eom head unit (it is a pre-amp, low level) to make a RCA connector in the line before it gets to the amp in the trunk. I am installing an ADCOM GFA-5450 four channel amp, it has no high level inputs. The ADCOM accepts nothing other than a RCA jack.

The oem HU sends FR, FL, RR, and RL to the amp in the trunk. I can pull the plug at the amp to get those connections, I have the wiring diagram pinouts and have everything in view now.

I have seen RCA connectors at Radio Shack, can I just soder a RCA conection onto a clipped low level wire. I have to confess to being clueless about RCA jacks in general. The only thing I know is that the center wire is the signal. In this case, there are no other wires, it is just a single strand of low level pre-amp signal. It seems that the RCA jack is also looking for a ground, but there isn't any.

This is a 1994 Lexus SC300 running the oem Pioneer based system, if that helps.

Some insight from those in the know would be helpful. Thanks,

Click to read more...

 

[jujumantb 10+ year member]

I fail to comprehend how it could send a signal with a single wire, you sure its not a casing with 2 smaller wires inside?

 

[bpkmrtoes]

LOC... line out converter... alot of shops have em... even circuit city

 

[theCybe 5,000+ posts]

Some Bose systems utilize a 'common ground,' it's possible that your factory setup does too. Thereby complicating the problem;

Rip it out and replace it. =)

 

[SCoupe]

Hey guys, thanks for the replies, my comments:

jujumantb: Yes, I could not be more certain that there are not 2 smaller wires inside.

bpkmrtoes: I have a non-amplified pre-amp headunit. Am I correct in thinking that LOC are only for hi level outputs from a factory radio. I want the non-amplified signal before the factory amp gets it.

theCybe: Yes, I think this is a 'common ground,' system. Ripping out the Lexus head unit is not going to happen, no ADCOM amp is what happens, the oem system is decent, an ADCOM is better. There has got to be a way.

Click on this thumb for the pinouts that I have available:

 

[jalverson 10+ year member]

You Should Just Have To Use A Line Out Converter And Tap It Into Your Speaker Wire Go To Elemtal Designs Website They Have Them On There Pretty Cheap, Or Go To Best Buy Or Circut City Or A Audio Shop

 

[SCoupe]

I know what a LOC is, I am looking for an alternate way to use the pre-amp output of my head unit, LOC don't do that, right.

 

[Bolognablake 10+ year member]

Err...I'm pretty sure they will work with the non amplified out-put. There will still be voltage in the lines.

Go lurk at some Lexus forums and see how they've done it.

 

[SCoupe]

Err...I'm pretty sure they will work with the non amplified out-put. There will still be voltage in the lines.

I'd go for that, has anyone done it? Seems like the LOC would be hell bent on reducing the level of what ever it get and it would be insufficient afterward.

I'm on the ClubLexus, a great forum, they all go with LLC/LOC. I was looking here because of the bigger user base thinking there might be another way.

 

[Bolognablake 10+ year member]

I'd go for that, has anyone done it? Seems like the LOC would be hell bent on reducing the level of what ever it get and it would be insufficient afterward.
I'm on the ClubLexus, a great forum, they all go with LLC/LOC. I was looking here because of the bigger user base thinking there might be another way.

Yeah, I'm a mod on JeepForum.com, but I lurk here all the time. Don't post much though. Heck I didn't even register till last month.

I get most of my info about factory systems and what-not from JeepForum, because most people there have had first hand experiences.

I don't think a quality Line-Level converter would reduce the voltage much. People run nasty systems with cheap no-name head units all the time, those things probably only put out .5v at the RCAs or something like that. I'm sure your OEM head-unit will do the same.

BTW, I'll be installing a couple of amps in my Grand Cherokee soon. I'll be using LLC before the factory amp also.

 

[Fran82 10+ year member]

SCoupe, just look at the wiring picture you attached. You'll see 2 ground connections in the plug. (P) Ground is your (P)ower ground. (S) ground is your

(S)ignal ground. It is not uncommon for a factory amplified system to have a common signal ground to the amplifier. If you chose to use the factory signal without a LOC you'll need to add wires onto that ground and then connect the RCAs as you mentioned. Positive signal goes to the center pin of the RCA and the ground goes to the outer ring. The only real concern with what you are doing is with the signal voltage that is coming out of the HU. There really is no way to know what kind of output you're getting until you hook everything up. If you have a weak signal and the ground isn't very good you may be amplifying quite a bit of noise. Hope this gets you going in the right direction though.

 

[NewToTheGrounds 10+ year member]

if u tap a wire does it not get a crappyer feed to where ur out putting it?

 

[Bolognablake 10+ year member]

if u tap a wire does it not get a crappyer feed to where ur out putting it?

¿Habla inglés?

 

[SCoupe]

Hope this gets you going in the right direction though.

Fran82, yes, that is the right direction, bullseye to be precise. Got to work on the noise, my first connections were sloppy to test the theory. Thanks