Over the years I have made it a point not to trash any theremin design as we can learn something from all of them. I will not even call them a toy.
What I complain about is posting theremin non-sense that one else can build and the designer will not demonstrate a single simple sound byte. I cannot play yet post a lot of samples so others can understand what I am trying to explain. Good theremin sound exists in a very narrow window.
I find this tube theremin pretty and the simple question I keep asking is what does using vacuum tubes add to the project besides making it pretty. If I was going for the finest theremin voice I would also go with the vacuum tube at least in the first stage for reasons most do not understand.
The designer is following this thread no doubt and he chooses to keep anyone from hearing what his final results are, we can make it better.
Over the years TW can be brutal but there are a few who have developed good theremin instinct as they were invited and could help others improve their results. Then there are the others, not so nice.
The first correction to help this design is to figure out an effective way to drop the volume loop down 25 cm and to the left to lower it below the main board, like an upside down L
I have many proven ideas to help with any theremin, tube or solid state, you just have to look.
Christopher