Hey there.
AC Expo -they had these on hand....LOL.
Could demo them to your hearts content.
The principle is that you have different tracks programmed into it & when you break any of the six laser beams, that track which is programed for a specific beam, plays.
Not like a theramin, which uses EM energy to make music.
About 1 1/2 years ago, the owner called me - not sure how he got the #, but he was telling me about this new product he developed & asked if I would be interested in demo'ing it, etc...
Not seeing the potential at that time, I politely passed - Yeah, I'm kinda kicking myself on that one.... Oh well.
Cheers,
Joe