Upgrading the Etherwave Theremin 

[Edit: They seem to have resolved the incompatibility issue in 2021] From ethermagic.eu: "It appears that Moog Music inc performed a modification on the latest production run of the Etherwave circuit board which risks some instruments to have a restricted pitch range after installing the ESPE01 module. We are investigating the issue and present a solution in short time. If the serial number of your Etherwave Standard is higher than 30000 or higher than 7500 on your Etherwave Plus, please put your ESPE01 upgrade plans on hold for the moment. We will publish updated information in this place, soon." So, yes they've changed the circuit, but it's unclear whether Moog has made it unnecessary.

Yes, the main difference in the is the additional CV converter PCB in the Plus, so the insides will look different. The Big Briar Etherwave that I mod in this video is also a little bit different than a modern Moog Etherwave. When you order the mod from Thierry Frankel, you will select the Etherwave model you have and it will come ready to install. (link in description) The installation is slightly different in all three cases, but it's very similar.

Lily Ruby Probably not...Thierry Frankel does this in France, but if you’re in the US, you can email bloopclick@gmail.com and we can talk about it

Sorry, I don't know anyone specifically in the US besides myself who I can recommend. Any competent electronics tech should be able to pull it off though, the most touchy thing is making sure you don't wreck the tuning while you're working.

The added signals are multiplied as they go through the diode in both versions. What are you suggesting that would require fewer parts?

@@bloopclick Если использовать вместо диода транзистор. Один сигнал подавать на базу, а второй на эмиттер. Тогда буферные каскады ненужны. If to use the transistor instead of the diode. One signal to give on base, and the second on the emitter. Then buffer stages are unnecessary.

It's used in my handmade theremin

@@yurykitaev368 Interesting...