Yeah, I guess Lev did have a version with a knob, but notice he abandoned that design?
And Charlie, to answer your question, I would say not: Lev didn't start calling it the Theremin until he'd developed the two antenna version. When he had a one antenna version, he called it an Aetherphon.
DiggyDog, a foot control can work. Of course, then if ethan wanted to control two at once he'd be using all four limbs at the same time, each moving separately. That's possible, some drummers do it, but it's very hard.
Ethan, have you ever played a single theremin to the quality level that you want to? I really suggest you try that somehow before you go on with plans to create a double theremin, because I really believe that when you try you're going to decide something to the effect of "oh dear, one is hard enough!"
Diggydog, my review of the AirSynth is on my web site at
http://theremin.tomfarrell.org/
In general, it's a fun toy and kids love it, it's a nifty noisemaker, but I have a difficult time labeling it a "musical instrument". I can easily imagine using it in some way as part of a musical performance, but not melodically... actually, as I say this, I realize I sorta did use it once for music: I took it to drum circle at a science fiction convention, switched it to one of its drum modes, and played "air drum" on it. However, I did that just for coolness value because it was a science fiction convention, it would be easier and more precise to just use set of bongos. And it wasn't a melody. (People did think it was really cool though.)
