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Recently I modded my Moog Etherwave Plus theremin and started seriously learning beginning theremin. I’ve run into a few surprises along the way, so I just thought I’d compile it all here in one place. I hope this helps!

Exponential or linear pitch field

The theremin has historically had an exponential pitch field, where each octave distance is smaller then the previous one. This means that you have to learn different hand positions for every single octave and, by extension, every note.

Carolina Eyck makes a strong case for modding your theremin so that it has a more linear pitch field. It’s not perfect, but it becomes much more linear when you do that, so that your hand positions are mostly the same for every octave.  If you are just doing sound effects, then this won’t have as much value for you–but if you are playing melodies then seriously consider doing this. Keep in mind, you’ll void your warranty.

I successfully modified my theremin with the ESPE01, as recommended by Carolina Eyck. It was a bit tense for an inexperienced solderer as myself, but it paid off! More info at the end of this post!

Tuning your theremin

Unless you mod your theremin, you shouldn’t need to tune it–the pitch knob is all you need. But if you do need to tune it, then check out this post on the topic. The key point here is that you have to open the cover to tune it, but the cover changes the tuning. So they recommend setting the zero beat to be about 3 inches from the antenna.  And on a side note, changing L5 seemed to do nothing by the time I got L6 to where I wanted it–so there does seem to be a very specific octave range for the theremin that I was not able to change.  This is a bummer for me because I play a lot in the top octave.

I experimented a little with the cover and screws, and the screws seemed to alter things very little. It’s really the cover that alters the pitch field. So, if you want to do some trial and error, you’ll get pretty close by putting the cover in place without the screws. That makes it easier to go back and forth while tuning, if you really want to. Then you can install the screws and they will alter the field very little.

Setting the zero beat

The way the zero beat works, is that the pitch decreases as you move away from the antenna toward the zero beat, and then it starts to increase again as you continue to move away. Turning the pitch knob to the left decreases the pitch field, and to the right increases the pitch field. If you’re moving your hand toward the antenna and the pitch is decreasing, then the zero beat is somewhere between your hand and the antenna.

A quick way to mute the theremin

The volume knob doesn’t turn your theremin off, it just adjusts the sensitivity of the volume antenna. And you don’t want to turn your theremin off either, because it takes a while to warm up again. You could get a volume pedal if you have extra money to spend. But the quick way to mute your theremin is to just loop the audio cable over the volume antenna. Done.

Warming up your theremin

The theremin really does take about 15 mins to warm up, so you want to turn it on early and leave it on. With  my theremin, the pitch field expands over time, reducing the number of octaves. I have to keep adjusting the pitch knob to the left to compensate–until it warms up.

Modding your theremin

I have very little soldering experience, but I’m so happy I went ahead and modified my theremin to be more linear with the ESPE01. There’s a cool demo by  Carolina Eyck that shows you why this is so useful.  Here are some tips when installing the ESPE01. NOTE: This is at your own risk–do not do this unless you understand the risks and will take them on yourself.  Please also note that I am not giving you instructions here, but rather tips and tricks to enhance the instructions they give you. Follow their instructions and, when in doubt, ignore me. Lastly, this is my own experience–I am not an expert.

Learn how to remove solder. Typically you use a tool with some kind of suction that sucks up the melted solder. I can’t emphasize enough learning to use the tool . You can get super cheap soldering kits that include this tool, so get it.

You will also need some tweezers or tiny needle nose pliers or both. These are useful for removing or inserting wires and pins.

And a wire cutting tool where the blades are close to the tip. Those all-in-one plyers/cutters/strippers aren’t going to work. You might need to strip one wire, so have some wire stripper handy.

I found that a mounted magnifying glass was really useful because you’re working with such tiny spaces surrounded by a lot of circuitry that you don’t want to mess up. My magnifying glass comes with a stand that also has clips that you can attach to the circuit board–super useful.

First you remove two capacitors. If you are like me, you completely eviscerate them as you get used to the heat of your soldering iron. For the newby like me, you’ll be very glad that Ethermagic is kind enough to include two new capacitors. But if you want to feel like a pro, then practice how long it takes to melt solder with your soldering iron. You need to touch the iron to the connection between the wire and the circuit board, and leave your iron there only long enough to melt the solder. Then they will pull out. The video makes it look easy, but it’s not. Wires conduct heat very well, so the longer you hold the soldering iron against the wire, the hotter it gets.

When you remove the capacitors, you will want to also remove the remaining solder using the tool I mentioned. It’s far easier to insert the new capacitors if you’re not trying to also melt some existing solder. It’s far easier to insert one end of the capacitor and solder that with fresh solder.

For installing the new capacitors, just follow the instructions. It’s a weird hack, but it totally works and looks just like the pictures and videos.

The same goes for removing the audio wire if you have an etherwave plus. There are also some additional connections on the board where you are inserting the ESPE01 that are unused but do have solder on them. Remove the solder from those, because you are sticking a bunch of pins into connections all at once. You can’t keep a bunch of solder melted all at once. Instead, suck up all that pre-existing solder so that you can very easily slide the pins into the connections. Then solder each connection. Make sure the ESPE01 is directly perpendicular, because it will be right up against the cover.

When you remove the audio wire, try not to mess with the end of the wire. You will have to stick that wire into a new connection on the ESPE01 and, if it is frayed even a little, it will be extremely difficult to insert the wire on the ESPE01 board. I had to cut the wire just a little to get a fresh end, and strip it a tiny bit so that it would properly insert into the connection. You can’t mess this up. You have very little wire to work with in the first place, so really be careful that you have a pristine wire.

And then lastly, remember that the cover changes the pitch field. Not only will you need to retune the theremin, due to your modification, but you’ll have to more or less guess. As I said above, the recommendation that worked for me was to get the zero beat around 3 inches from the antenna. Then put the cover back on and tweak the pitch knob a little bit more as needed.

Have fun!

That’s all I got for now. It seems like there are a lot of videos out there that teach everything beyond this point. Let me know if you think of any other basics that you wish you had known.  Thanks for reading, and have fun!