Stereo sound
 

Being a bit of an electronics tinkerer, I was interested by certain rumours of "intelligent" use of the stereo capability of modern headsets. And am wondering how I could implement such an idea to advantage. What would be a sensible "algorithm"?

One COM:
* nothing active: background music in stereo (L->L, R->R)
* as soon as anything active: no more background music
* only intercom active: intercom on L+R (or only on L?)
* only COM active: COM on L+R (or only on R?)
* COM and intercom active: COM L, intercom R or VV

Two COM:
(far too complex to imagine, as yet)

Speaking as a musician and occasional audio engineer: anything panned hard left or right (i.e. strictly only on one side) is unnatural and probably distracting. The idea of some separation (I'd go for intercom R, radio L, as R is the natural side for the pilot to hear the other people in the aircraft) is an interesting idea but I wouldn't separate them totally. Which in practice means that you won't be able to do it without incorporating a small mixer and that's way over the top for an aircraft audio system I'd say.

You need to try a Garmin GMA350 audio panel. It features all of the directional separation you're considering and works really well.

@tmmorris: interestingly, I used to be a musician and a bit of a sound engineer too, though less and less now. I fully agree that hard panning might be distracting, and that is why I considered having certain sources permanently limited to one side - for the sake of circuit simplicity. One could have them, attenuated, in the other channel, too, though.

OTOH a small mixer is so easy to implement (even without resorting to SMD components) that I see it as quite feasible - a quad opamp goes a long way and one can lightly accomodate several. Actually I had a vague image of, doubled for pilot and co-pilot, a stereo "power" amplifier such as TEA2225, preceeded by a summing opamp. Then add a bit if level detection, logic, programmed attenuation &c, nothing really hard.

@wigglyamp: you must be referencing the source of my vague thinking. Is there any written description of what the device actually does?

The latest audio panels do have spatial separation built in, i.e, Garmins GMA350 and up, as well as PS Engineering from certain 8000series up.

(When I replaced my audio panel a while ago, I had a look at it and decided against. It did not feel right in a GA aircraft with its little work load and I found the fixed distribution distracting - the system does not know your heads actual turn .. may be different feeling in combat fighter.)

I have the Garmin GTR200. By default, when you are monitoring the standby frequency, you get primary on one channel and STBY on the other. Turn off the monitor function and primary is on L+R channels.

It seems a little odd at first, but you soon get to appreciate being able to differentiate without looking at the radio.

Auxilliary input is stereo capable too.