Theremin featured in "The Big Door Prize"

Has anyone seen The Big Door Prize on Apple TV? A theremin is featured in the first episode and makes some more appearances throughout the first season. The main character receives one as a birthday present from his wife so maybe he'll "try something new for a change". 

Obviously the actor is not playing it live during filming. Some of the early scenes have the pitch antenna response reversed, but later in the first season they seemed to figure out how it actually works and the dubbed playing aligns fairly well with the actors' gestures.

I'm curious - anyone know who played theremin for the filming?

My friend told me to watch this for this reason.. I read some spoilers and apparently it becomes a pretty integral plot point. You can sort of get that from the trailer... https://www.youtube.com/watch?v=Mu-KfLd-d9U

Apparently in the book it was a saxophone or something. Interesting that they changed it.