: The OFFICIAL Hijack your XM for an AUX input thread!



Playdrv4me
04-03-05, 08:17 PM
Alright,

So after chasing around for two days on this forum, and the Avalanche owners club of America or whatever they call themselves over there, I FINALLY did it. Hopefully this will serve as a guide for someone wanting to do the same. Essentially the key is just having the pinout. Keep in mind that this is for the connector on GM TRUCKS built 2003 and up, BUT its very possible that the XM input on the cars is the same or similar.

I followed the Diagram below and essentially just spliced into the BRN/WHITE and GRN/WHITE leads, then I ran a Stereo RCA to 1/8" Miniplug cable down and out the dash to reach approximately to the storage compartment just under the radio where my Ipod usually sits. The downside is you will get line hum due to being improperly grounded, but high quality cables and an electronic device connected through the 12 volt power source should alleviate most of this to where you can only hear it between songs or in quiet passages.

http://www.chevyavalanchefanclub.com/attachments/XM_Conn-EndView_ID.gif

For those who dont want to or cant deal with the work involved in doing this, PAC does make a cheap connector thatll do the same thing.

maydog
04-03-05, 11:43 PM
Why did you not splice in pin 10? Without the common signal the left and right subtrach from each other and I would think the audio would sound quite strange.

Also putting a proper common signal in should eliminate some of that ground loop noise you are getting. Also, you could try using ground loop isolators to eliminate the hum.

Playdrv4me
04-04-05, 01:52 AM
Splice what into pin 10? I noticed that in the diagram but the soundstage is unaltered despite not using it. Right is right, left is left and the phase is correct. Its funny you mention ground loop isolators. I really have never used one, but somehow I knew a ground loop isolator is probably what I would need in an "ideal" situation to completely eliminate the hum. However, when the truck is running its barely noticeable.

maydog
04-04-05, 02:12 AM
The audio signal needs to be referenced to a common point. In most systems this is the gorund, however there are lots of different grounds to use. The audio jack has three conductors, right? 1 for left, one for right and one common. Withough having common wired in, the radio is going to reference to the chassis ground. The problem is that the Ipod is grounded far from where the amplifer is and so the grounds are not the same.

You are going to pick up a lot of nose due to this. Using the audio ground should eliminate much of it. If it is connected correctly, you may notice a large improvement in the hum if you run the ipod off of batteries leaving the power adapter disconnected, this will tell you that you have some ground loop issues. Actually if you disconnect the powersource as it is connected right now you may get no sound or a difference between left and right channels as the common connection through the chassis is eliminated.

An isolator is basically an transformer that allows the signals on the input and output end to be referenced at different levels, eliminating the need for ground voltage to be the same.

Playdrv4me
04-04-05, 02:20 AM
Alright good info. So how should I utilize the Common? Does it need to be spliced in with the left channel or what?

maydog
04-04-05, 02:29 AM
I am not familiar with the output of an IPOD, but I am guessing that it has a standard audio jack.

How did you splice the l and r channels out of the device? What type of wire / jack did you use?

Chances are if you cut and stripped regular headphone type wire, the common is the bare copper conductor surrounding the l, r channels. Sometimes a fiber of some sort is mixed in with the copper wire.

Playdrv4me
04-04-05, 02:50 AM
Heres what was done.

The two leads for L and R going into the multifunction connector were cut and spliced into with a simple 1/8" Stereo RCA (cut the RCA ends off and spliced into the L and R on the cable) to minijack cable, so that I could leave the minijack end hanging near the dash for whatever I want to connect to. The Ipod DOES have a minijack output, however it can pick up noise so I actually dont connect there, Belkin actually makes a 12 volt power source with an integrated volume control and minijack that takes its input from the multifunction connector on the bottom of the ipod. This is what the cable plugs into directly.

maydog
04-04-05, 10:25 AM
Hmm...

Does this connector must have a power ground. If it does not have a separate audio ground I would splice in the power ground to pin 10.

Do you have a photo or some documentation on this multifunction connector?