The multiple-theremin performances keep coming! Thierry recently posted this on YouTube:
First public performance of Meike Degand (D), Wolfgang Streblow (D), Wilco Botermans (NL) and me (Thierry Frenkel, F) as a theremin ensemble on November 25th, 2012, during the Without Touch 5.0 Theremin Festival in Lippstadt, Germany.
This piece is a traditional Barbershop song which I arranged for 4 theremins and started working on it with this ensemble during the Theremin Summer Academy 2012 in Colmar, France.
Notice how they have to stand on separate corners of the stage. This is to reduce cross-talk between the theremins. If you've never experienced the effect, it can be maddening! Not only do you need to move each theremin away from the others' "control zone", you really need to have them on separate circuits entirely.
Enjoy this fun performance!