One or two wires for headset jack/mic

[Tokirbymd]

So looking into my passenger headset jacks a bit better (anticipation of new stereo audio panel and what work it will entail) I’ve discovered that the rear headset and mic jacks may have been installed incorrectly. The aftermarket PM1000 intercom calls for 2 separate shielded 2 conductor wires- 1 for mic and 1 for headset with shield grounded only at the panel. However on mine, they used only 1 shielded 3-conductor wire and used the shield as both the Phone Lo and Mic Lo (these 2 outputs were soldered together). Is this common to use shield for a return? Looks like I may have to rewire afterall for the new audio panel to get stereo headset out

 

[Dan Thomas]

So looking into my passenger headset jacks a bit better (anticipation of new stereo audio panel and what work it will entail) I’ve discovered that the rear headset and mic jacks may have been installed incorrectly. The aftermarket PM1000 intercom calls for 2 separate shielded 2 conductor wires- 1 for mic and 1 for headset with shield grounded only at the panel. However on mine, they used only 1 shielded 3-conductor wire and used the shield as both the Phone Lo and Mic Lo (these 2 outputs were soldered together). Is this common to use shield for a return? Looks like I may have to rewire afterall for the new audio panel to get stereo headset out

Some do that. The plugs on your headset use the jack's barrel for return, and the shield is often soldered to it.

The jacks should be insulated from the airframe to avoid "ground loops" that introduce unwanted noise from stray alternator and strobe currents.

 

[Jay Urish]

I just installed a stereo audio panel in 44T. Garmin gma 347.. For rear passenger headphone, I used 2conductor shielded and blue for right blue/white for left and shield for low. For the mic I also used 2ond shielded and used white for low/ring and blue/white for barrel-hi and left the shield floating per the install manual.