Maybe this will help: http://www.vx-aviation.com/sprocket/...s-2/AUDIO2.pdf

V

RV3 LEMO Plug
 

Here is what I did in my RV-3B. If you look at the bottom portion of the diagram it shows how to hook the LEMO wires to legacy headset jacks. This makes it really easy to add LEMO.

As a rule of thumb I might agree. In fact I take it one step further than you and make sure any system device such as this gets its power ground from the common avionics ground point. But in this case I followed instructions. Bose specifically specifies these exact wire connections in its documentation and on on its drawing. I speculate that Bose realized if they showed the black wire going to ground the installer might decide to ground locally rather than the avionics ground point, which could induce ground loop interference. So while I stick to generally accepted practices like the avionics ground point when no guidance is given, when a manufacturer like Bose says to do it a certain way who am I to argue? And my installation works great.

Jim

I completed wiring both LEMO plugs last night. Here is what I found:

1. IF you want the connector to be flush with the seatpan/ramp, then installing it per KAI (1 inch aft of the exist jacks) won't work. The LEMO pigtails interfere with a stiffener. I question whether or not someone would want this plug to sit flush though.. I picture breadcrumbs getting into this connector over time. If you allow the connector to protrude at the maximum amount possible (about 1/4"-3/8"), then you may have a chance to get the pigtails to not be squished up against the stiffener.. but it seems safer to just install it 1" forward of the existing connectors ( as measured from the center of the mic hole).
   
2. The LEMO pigtail was slightly confusing. Normally, I'd peel back the audio cable braids a bit and put a solder sleeve on it and "convert" the braid to a wire. That has already been done for you -- the headphone braid is a black wire w/ white stripe .. and surprise, the mic braid is also a black wire w/ white stripe. Which is which is an exercise for you and your multi-meter.
   
3. There IS a red pigtail for power, AND a black for its return (in my previous post I didn't notice it, sorry). Where to ground it? probably the pilot-controls/wingroot point. I'm sure the headset has a DC-DC converter and some noise filtering caps in it.. and the audio/mic line grounds are grounded at the radio/audio panel only.. So I don't think there will be any noise issues. Though the true test is always in the air.
   

Overall, if I could do it over again, I would have just called Stein, thew them some extra money and had them wire in the jacks (I solder electronics all the time, but adding on wires to terminals after the fact is always a pain compared to doing everything up fron). I don't want to say it should be a STANDARD feature to the -12 because it adds about $100..but could be offered as a factory/Stein option.

This is in the finish kit, not the avionics correct? I just ordered my finish kit, wondering if I should try the suggestion to have Stein do it...

Yes, I'm sure Stein would add the plugs for you for a nominal charge. But, if you do it yourself, I recommend doing it before putting the harness in the plane.

I should mention now that after my initial wiring of the plugs in April, I finally got around to testing it with a headset. I found that I had no audio in my right-ear.

After much head scratching, it turns out that the LEMO diagram in the latest RV-12 electrical diagram was incorrect. After consulting with the mothership, it appears that someone cut-pasted the RV-14 diagram into the RV-12 schematics. While the wiring is essentially the same, the RV-14 uses a different wire color for headset-ground and headset-right. (white/orange and white/blue are swapped).

During testing, I noticed that even with new legacy jacks, I got the typical crackling/scratchyness when rotating or jostling the headset's connectors.. which I sorta expected.. I've experienced that in almost every plane I've been in. The LEMO plug on the otherhand.. the audio was rock solid even when applying abnormal forces to the connector.

No Joy
 

Response from Stein in regards to adding LEMO plugs to an RV-12iS wiring harness:

The ground wire on a lemo connector feeds both the power ground AND the headset speaker ground. I believe it is recommended that this ground wire connect to the intercom ground buss or headset ground pin, depending upon intercom type. Connecting the lemo ground pin to an airframe ground introduces the risk of a ground loop on arguably the device most sensitive to ground loops, the headset speakers..

Larry

Your welcome to purchase the jacks and add them in yourself though if you'd like? They are $75.95 per place, and require an additional power wire.

Wow, that's a lot of money. $75 will buy 2A Alkaline batts for my Zulu3's into the next century...

Larry. Good catch. You are correct.

That is depicted 8 posts up in the drawing. The LEMO ground is attached to the headphone ground circuit per Bose's instructions.