6-pin LEMO headset plug
 

Newer -iS models have power leads going to the headset jacks as part of the standard wiring harness that Stein builds for us.

The KAI mentions this by basically saying hey there?s extra power leads, so if you want to install a 6-pin jack for a Bose-type headset, go for it.

Question for the group is .. should I still wire up the conventional jacks as well? Will it introduce unnecessary noise? Should I just repurpose one of the two jack holes? (the LEMO hole is 14mm with two flat sides of 12mm ? bigger than the existing holes)

I have used ANR headsets in my RV-6 for 20+ years. Three or four years ago, I added LEMO jack for Lightspeed PFX as they used up batteries fast. (Battery life was less than 1/2 what other ANR headsets were. I added LEMO jacks so that I could get rid of the batteries. Shortly there after, I changed to a different brand of ANR headsets.

After adding the LEMO jack, I wonder why I did not do this sooner. Most ANR headsets (other than Lightspeed) with LEMO plugs still will work with batteries and an adapter in other GA aircraft with only the "standard" GA jacks.

The addition of the LEMO jack to the "standard" GA jacks created NO noise and I nor any passenger have been able to notice any change in the Bose A20 headsets.

My recommendation is to leave the standard GA jacks just in case someone else wants to use some other kind of headset and does not have an adapter cable. At the present time, I am planning on have both GA and LEMO jacks in my RV-8 under construction.

I added LEMOs to my iS too. Couple of my experiences I?ll share. Make the provisions in the harness before you install it. Much easier to do with the harness on the bench than in the plane. I drilled small holes in the GA jacks where the leads were soldered on rather than try to break into the harness wires. Also, there is a stiffener that runs under the seat ramp where the jacks are installed. Had I not looked under the seat ramp and blindly added the hole for the LEMOs behind the GA jacks as suggested in the KAIs, the back of the LEMOs would have run into the stiffener. Instead, I used the forward GA jack hole for the LEMOs, after some filing to accommodate the LEMO?s slightly oblong diameter, and drilled a hole for the other GA jack where Van?s indicated mounting the LEMOs. Just check your physical condition with your LEMOs before drilling. Mine were the Bose LEMO jacks. Just too long to work as Van?s suggested. And because the holes are different for the GA vs. LEMO, you can?t easily decide to swap the GA for the LEMO after you install the LEMO. Just measure twice and drill once.

What he said, ...
 

Ditto Sobek, I added a LEMO to the Co-pilot side, and left the GA plugs. That allows both for the passenger. Haven't added LEMO to the Pilot side (yet) but would be doing that configuration in any new panel.

No interference or noise issues when properly wired per specs. Having to change batteries in the GA headset, when the ANR fails from dead batteries, is frustrating and distracting. (Which pocket did I put those spare AA"s in?) :eek:

At SteinAir we wire all 3 jacks together at each station if the customer wants both types, and the only extra wire is the power lead for the ANR headsets.

I didn't bother installing the regular mic and phone jacks, but put LEMO plugs on both sides. I have two sets of Bose headsets and just keep the second one available in the plane, and with over 500 hours now, it's not been an issue.

Noting that I, and most folks, prefer ANR headsets, I doubt I'll ever install standard jacks again. As an option, you can buy an adapter for 6-pin to 2-jack plugs from Sporty's, and I'm sure other places, if you really want to keep an option open for someone's standard headset.

The easier solution (and a lot cleaner on the panel) would be to carry an adapter cable of your own. The Lemo to GA adapter is only 6" long and could live in the passenger side pocket. I'd rather do that than wire two sets of jacks.

In the case of the 12iS, dual GA jacks come already soldered to the wire harness, it?s simply a matter of adding the LEMO to the harness vs. removing the GA jacks. Plus, the seat ramps where the jacks are installed are pre drilled for the two GA jacks, so installing only the LEMO would leave an open hole. I would also assume that removing the GA jacks from the prewired harness might technically invalidate E-LSA certification, if that?s one?s certification objective.

Thanks for all the input guys.

I will install the LEMO plugs in addition to the legacy plugs. I didn't notice that the 12iS electrical schematic (as found on the Van's website) had a section addressing the wiring (lower-right corner of Page 3).

It basically says install in-line with, and 1 inch behind the existing jacks. The wires are 22-gauge (which is what the LEMO install kit from Bose uses) and the length is 6". And to connect/solder the leads onto the mic/headphone jack's tabs.

I assume the headset's power pin uses the headset or mic ground to complete the circuit, as there's no dedicated pin for the power ground.

The black wire coming from the Bose LEMO is the power ground. It needs to be tied to the airframe ground to complete the power circuit.

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.

Agreed. Since Stein will only sell you an expensive Bose jack and since you'll have to do some soldering anyway, I'd suggest buying the actual LEMO plug from an electronics parts store, and soldering the wires to the plug.

https://www.mouser.com/ProductDetail...ACYiSzTw%3D%3D

$30 per plug .. and you'll need 1ft of 2-wire shielded cable for the mic, and 1ft of 3-wire shielded cable for the headphones. Though for the 6 inches of wire you'll need per headset, you can probably get away with non-shielded.

I agree. Thanks for the link.