I wish I had one of the new GMA 240 audio panels. The 240 has a stereo input jack right on the front panel, which the much more expensive GMA 347 that I have does not. So to enable my passengers to plug their iPods into the panel and hear the audio in their headphones, I had to track down and wire a separate 3.5 mm audio jack – one of the fancy switching kind that uses a separate set of contacts when the plug is inserted. This will let me use the single set of input pins on my audio panel for both external audio and XM music from the GDU 375 MFD.
I made this little bracket to mount the jack on, since the threaded part of the barrel is way too short to go all the way through my 0.090" thick instrument panel:
The mounting hole is drilled oversize to accommodate the enlarged plastic shoulder on the jack body. This insulates the jack from the metal panel, to prevent the possibility of a ground loop (which is important for quiet audio).
A mylar washer under the nut keeps things insulated there too:
The bracket is attached to the panel with a pair of #4 screws, and the hole in the panel is oversized to keep the nut from shorting to ground. Functional and looks good too.
Six wires are soldered to the five contacts on the jack… two separate pairs of left and right channels, and one common low connection. The two sets of wires also share a common shield.
The little ear on the bracket is for an adel clamp that supports the wires:
Here's what it looks like installed in the panel:
My dad was in town for Mary's graduation, so I enlisted him to help test the audio quality.
Now this is some flying music:
I don't have an XM antenna hooked up yet, but I verified the MFD side of the audio wiring using the 1 kHz factory test tone:
I noticed that this bundle of wires behind the subpanel is starting to get pretty close to a couple of subpanel rib flanges. I will probably put some cat grommet on the flanges, and tie-wrap some plastic conduit around the wire bundle too.
