[C6] How To make the Line Level/RCA Adapter Harness
 

One of the things I discovered early in the process of working with the C6 stereo systems is that there is line level signal available in the factory harness in ALL of the systems, Delco and Bose and including NAV. This is true of ALL of the model years of C6 through 08 and I expect that it may continue throughout the generation, though that is speculation on my part.

This harness you create will become a "Y" adapter, with one side of the Y being the factory connector and the other being RCA outputs to hook to an aftermarket amplifier to drive a full system or even just a subwoofer. This is the BEST way, hands down to get this done. You do NOT need a Cleansweep and using the full PAC AOEM-GM24 adapter adds cost and worse, adds an ugly EQ curve that rolls off bass that will hurt the end result of your efforts.

So, enough pre-amble, here's now to make it...

Parts you need:

PAC ADD-GM24
http://www.sonicelectronix.com/item_...+ADD-GM24.html

RCA Jack Red Plastic Part Number 090-266
http://www.partsexpress.com/pe/showd...number=090-266

RCA Jack Black Plastic Part Number 090-265
http://www.partsexpress.com/pe/pshow...number=090-265


These are recommended vendors and parts, you can use any female solder-on RCA's you care to use, Radio Shack has them as well. The ADD-GM24 is the only part that is not optional, and though you may find it elsewhere the easiest place I have found to get it is Sonic Electronix.

You start by cutting off the connector that is intended to plug into the evil OEM-1 box that induces the aforementioned nasty EQ curve. These are the wires you will solder on to the female RCA's. Here's what it looks like:

http://www.lazyassgeek.com/blog/wp-c...3/misc-128.jpg

Solder on the connectors using this table of wire colors:

Left Front + White
Left Front - White/Black

Left Rear + Green
Left Rear - Green/Black

Right Front + Gray
Right Front - Gray/Black

Right Rear + Purple
Right Rear - Purple/Black

The RCA connectors will have a small lead in the center of the plug which is the positive(+) lead. The longer connector is the negative/common(-) lead. Be patient here, and you may want to buy a few extra connectors cause the leads are close together and it's easy to get sloppy and have to start over. The key is to make sure that the leads & wires of each connector do not make contact with one another, if they do the connection will not work. Also, make sure you slide the screw-on cover over the wire BEFORE you solder on the connector!!! :rofl:

When you're finished your harness should look something like this:

http://www.lazyassgeek.com/blog/wp-c...gm24-small.JPG


I hope this thread answers some questions and makes clear what you need to do in order to get the best possible output to feed an aftermarket amp while keeping the factory head. :thumbs:

Very nice

K,

When you did your line out measurements, did you happend to compare front to rear output?
I am playing with a goofey idea, Im using the front feed in the rear and the rear channels to the front. This keeps the door chimes from the stock head unit almost normal instead of 110db in your face :)

Phil

Hey Phil,

I'm not entirely certain of it, but my hazy memory says the line out levels were identical. That's a pretty good idea to move that to the rear where you're likely going to damp down the gain on the amp anyway. :thumbs:

Dan

The front and rear outputs from the deck are identical, flat and undistorted (I tested them with Liberty Praxis) at normal levels. The differences in the outputs between the front and rear speakers is due to the EQ and crossovers built into the factory amplifiers. We (Komo and I) did not yet analyze the amplifier outputs, as it doesn't really seem to have any value.

x2... they are identical.

i have used just the rears for one customer who didnt want the chime at all

What about the subwoofer out and the center channel? does onstar run through the head unit or to the amp? what color wires are the center and the subs?

its those 4 channels to the amp the imaginary POS excuse for a center channel and the low pass for the subs is all done from the oem amp

onstar comes from the headunit as well as the chimes, a search will show all of this

:iagree:

The factory head only outputs 4 channels, R&L each for F&R.

This is great!!!! Thanks for posting this. I have ordered the parts and am almost ready to go.

Remote turn on wire?
 

Nice clean job, which wire in the harness is the remote turn on for the amp?

Thanks -c

There isn't one. The factory system uses the data bus for this instead of a switched 12V wire. See this thread for what you need to do:

http://forums.corvetteforum.com/show....php?t=2052253

seems simple enough. If I wanted to run a front stage then a sub would I just use one of the "rear" RCA jacks and run it through the low pass filter of my amp then to the sub? Would it matter if I used the left or right rear output?

It might matter because you'll be getting a stereo output from the deck. Now how much of the low frequency is actually split between the channels is hard to say, but it's something to consider. Does your amp have a "mono" setting where you can feed it a stereo input and have it sum the signal to a mono output?

Yes, it does. It's an Alpine PDX-5 so even on the sub channel input it takes a stereo signal.

Then just plug 'em both in, you'll be all set. :thumbs:

haha, I lied... I just looked at it and it doesn't. Only one set of RCA jacks for the sub channel. Would a y-connector be the best option?

http://vault.alpine-usa.com/products...PDX-5%20OM.PDF

According to the diagram there is a SUB W. (L) and a SUB W. (R) connection. Plug the rear outputs from the harness into those and you'll be all set.

you're right... too many projects at once. I saw two females and thought one +, one - (not L/R)

Komoman,

the rca plugs at radio shack have a + positive and a ground connection, not a -negative. Does it still work the same?