Theremin World Recent Forum Posts

Beginner, seeking advice (by ILYA)

" to build the antennas with" - indecisive

I dunno about the US, but over here in Russia, the cheapest option is these things they call "greenhouse hoops in plastic coating" or "plastic-coated steel tube greenhouse".

You can find them in the gardening sections. The common diameter is about 10mm. They are also available in straight versions, 3 meters long. They’re usually just plain black steel that rusts, covered in green PVC.

I peel off the green coating, wrap it with gold tape, and then put clear heat shrink tubing over it. Looks pretty decent, I gotta say:
https://antiradio.narod.ru/theremin/paradox/

BTW, the Paradox circuit is relatively simple, and it achieves a pitch linearity comparable to that of the T-Vox Tour or the theremins designed by the Russian engineer Lev Korolyov (often referred to as the "Kovalsky system").

Beginner, seeking advice (by indecisive)

JPascal, thanks for the recommendations. The CMOS 555 theremin looks like it'll be a lot easier to find components for; I'll see if I can get some parts together and get a prototype built soon. If it goes well, I'll post an update hopefully within a week or two, maybe sooner if I run into some trouble.

ILYA, thanks for the encouragement. Building the casing would be a bit out of my comfort range, but I'll cross that bridge when I get to it. Come to think of it, I'd better start looking for something to build the antennas with.

Beginner, seeking advice (by ILYA)

indecisive

If you’re an electronics geek and your hands ain’t made of butter, then putting together and tuning an electrical circuit, even a complex one, ain’t gonna be no biggie for ya. Trust me, the real grind for guys like us is building the damn casing and all that other junk – the metalwork, painting, finishing, and figuring out a solid design based on whatever scrap you got lying around. I’d say 90% of the time is spent on this non-electronic crap!

Beginner, seeking advice (by JPascal)

Hello, engineering student—what a great idea to choose a theremin project! Since your time is limited and you only have temporary access to an oscilloscope, I recommend that you don’t try out the Etherwave circuit. Why? You need to achieve a working result within a limited time frame, and there won’t be time for extensive troubleshooting.

You could f.e. replicate a nice, fully functional little project by the German engineer “ElektroUwe,” which he presented here in this forum a few months ago:
https://www.kulturgueter-schuppen.de/books/analog-music-electronic-circuits/page/cmos-555-theremin

The LC feedback method ensures stable oscillators with a high enough sinusoidal voltage at the pitch antenna, resulting in a good signal-to-noise ratio for the audio signal. The mixer produces good-sounding audio with harmonics. Ferrit core coils are sufficient for your investigations. The zero pitch can be easily adjusted via vary the voltage supplied to the oscillators.

If the pitch unit is functionable you can involve a loudness control. This is a gate, what opens or close in dependence of the hand capacitance to the volume antenna. Also a nice little project to examine and choice circuits for that. For both antennas use not to small or thin rods.

Please give here some feedback to your decisions and the progress.

Beginner, seeking advice (by indecisive)

Hello all,

I'm a third-year electrical and computer engineering student and for my Electronics final project, I've decided to build a theremin. I have a few semesters worth of experience building simple circuits on breadboards, two lab sessions worth of soldering experience, and about a month to work on this project.

Initially, I was thinking about building the Etherwave Standard, as I'd like to make something of high-quality with both pitch and volume control that I could use as a proper musical instrument afterward. However, after looking over the details of the build, I don't know how feasible this is in 2026; in particular, finding suitable inductors seems like it'll be a challenge. I thought it might be good to seek a professional opinion on this matter before I make any serious commitments.

Do you think it is possible for a novice like me to build (and obtain components for) something like the Etherwave in under a month? Should I perhaps pick a different or simpler theremin circuit? If not, are there any other considerations I should be aware of?

If it matters, I am in the United States and I currently have limited access to an oscilloscope through my lab sessions once a week.

Thanks for your time.

Etherwave+ as a MIDI Sample Library Controller (by Gigi)

Hello,
I am not sure where to post this but I am after advice on my etherwave plus. I would like to hook it up to a synth and possibly software on my computer.
So I am looking for advice on a cv to midi converter.
I don't have a euro rack but am beginning to see I may need one for this experiment. Or at least the power module and cv converter?

What is my best option preferably on a budget.

OR am I just better off getting a small synth that I can plug my cv out, pitch out into?

I'm a little lost on what to purchase to achieve my goals. Which is running different sounds/ effects through my theremin.

Any advice would be most welcome 🙏

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by dewster)

Sometimes a long audio cable on the floor is enough in the way of grounding.

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by dales)

I’m in the U. S. and paid the premium for FedEx, which does its own customs handling. I did not want to watch surface mail tracking show it not moving out of customs.

I suspect your hoped for setup with your headphone amp is not going to be earthed, also called grounded, and you’ll need a solution. I’m a beginner too, but I believe the OT, like the LV-4 and even the Moog Etherwaves, expect to get their earth/ground from the amplifier through the connecting cord. I don’t know what mobile/busking setups do. When I use a headset, I plug it into the amp. It probably doesn’t sound as good as your headphones, but I prefer hearing an amplifier, and I can probably take it to Open Mic when I’m ready.

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by harcel)

So fast! I ordered last Monday, it got dispatched on Tuesday, but only arrived in the Netherlands late Friday afternoon. Customs will probably keep it over the weekend, as I haven't yet seen the unavoidable bill. I hope to get it sometime next week!
Will have to see if I can get my grounding worked out. I have only few grounded power outlets in my house and obviously don't want to play from my bathroom all the time. The only amp I have for your l now it's a small headphone amp without earth....
The trumpet is long ago for me. I think it still helps in knowing some music theory, but I'll gladly regard myself a complete beginner. Enjoy the instruments!

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by dales)

Funny to find another trumpet player here. Those Clarke studies are good for theremin practice too!

I’m getting grounding from a keyboard amp with my LV-4, and I expect this to work for the OT too. I’ll get power from a single port phone block. Good luck avoiding ‘the hum.’

I ordered Friday morning and it will supposedly be here Monday morning.

Headphones (by harcel)

I was struggling with the exact same questions! My OT4.5 is still on its way, but I did some research and ordered some auxiliary gear (low budget, though...), so for results: some patience, please
From what I've found it should be possible to connect headphones directly, although that limits volume control to the volume antenna. Low impedance is good, but if it's a high sensitivity set, somewhat higher impedance should also be fine. Many bluetooth headsets have a slight delay in producing the sound (even when using an input signal from a wire), called latency, which would be very annoying and severely limits your ability for pitch correction. I ordered a headset that is purely wired, no Bluetooth possibilities whatsoever and no microphone. Alongside, I ordered a very small headphone amp, to at least have some external volume control.
Note, though, that if your amp is absent or not grounded (like mine is), you will need another way to ground the theremin. I'll try a laptop charger as well as a separate ground wire. I'll let you know how things go.

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by harcel)

Hi!
Such a lot of coincidence. I'm a former trumpet player, turning (hopefully) thereminist. I, too, was turn between a LV4 and OT4.5. A local teacher seemed to suggest the LV4, but he had not played one himself yet. He stressed the importance of pitch linearity (for beginners) and because of Carolina Eyck's endorsement of the OT4.5 for its excellent linearity, I went for that. It's with customs now, so fingers crossed. The teacher had some issues with grounding and noise on his OT4.5, which seems fairly common, so I guess care need to be taken there. I will report in due time.
Cheers!

Beginner here, torn between the OpenTheremin 4.5, LostVolts V4 and Burns. (by dales)

Sylvain, what did you get?

I’m new here, playing a Lost Volts LV-4 for about 50 days now. I also have an Open Theremin kit on the way. Our public library offers one free 3D print job per month, so I’m printing the case there to save a few $.
I was previously a trumpet player, in school and as an adult.

I like the Lost Volts quite a bit, and the video of Moon River above is the best I’ve heard this model played, so thank you for that. It’s fun that you can actually see his waveshape and filter settings.

I’ve watched videos, checked out books and methods, and am repeating my way through early Kip Rosser lessons 6-10. I can play bits of melodies especially when not thinking.

Let's Design and Build a (mostly) Digital Theremin! (by dewster)

PCB Logo Plates

The logo plates from JLCPCB arrived yesterday:

I was afraid that the insulating ring around the mounting holes would show up on the finished design, but I can't see them. They've since been removed from the KiCAD source file, which was slightly tricky, as KiCAD is all about electrical connectivity.

The printing is on both the front an the back, and there are minor cosmetic difference here. One side has three small bumps in exactly the same places on all plates - it's curious, and I would obviously prefer they not be there, but they're not super obvious. Both sides have small bulging around the mounting holes. Looking closely, it's clear that the white silkscreen is printed via horizontal lines. The solder mask is somewhere between gloss and flat. Anyway, good enough for government work!

Believe it or not, the logo plate is the most difficult 3D print for the old kit, with spray painting and sanding following, so this is a welcome relief! I can go ahead and order the main control panel and antenna plates now, though I wish I knew how to ensure that the top side wouldn't be the one that has those little bumps.

[EDIT] Here are the bumps (the image has been edited to make them more obvious, so the logo looks weird):

Let's Design and Build a (mostly) Digital Theremin! (by dewster)

"That task is an approach used in the design thinking method." - JPascal

I hadn't heard of that before. It seems to be a formalization of the iterative development process. The hard part of development is understanding what exactly to focus the development effort on. For a musical instrument, it's my strong belief that you have to play the thing yourself to fully understand what is going on. This dramatically shrinks the feedback loop, but it also introduces an element of subjectivity that is difficult, if not impossible, to combat.

"Your fundamental decision was to build a digital theremin and focus the human-machine interaction on the familiar way of playing. To achieve this, you aimed for absolute linearity, built most FX and other effects into the device, and added a pitch display. This concept clearly struck a chord with all the professional artists: reliable, stress-free, and offering all the possibilities of the playing style they’ve mastered so far."

Is there any such thing as a stress-free Theremin? :-) Using a sketchily grounded bag of water (human body) to induce tiny changes in capacitance for the control of arguably the most discerning of human senses (pitch) on an orchestral stage facing thousands isn't exactly a confidence inspiring scenario! Though I suppose everything is relative...

"The main difference to Lev is, he analyzed all possibilities essentially without reference to earlier developments; his ideas extended as far as polyphonic instruments and so on. In doing so, he had already optimized key aspects: the frequency range, the antenna shape, the length and thickness, as well as the spacing between the antennas. Even during the first performances, he experimented with influencing overtones using filters in the HF range, etc. His technique differed from that of Moog instruments in terms of heterodyne technology too, thereby laying the foundation for later developments."

Did Theremin's heterodying method differ all that much from Moog's? The EPro uses digital dividers and XOR gates, but Bob's other designs use diodes and such for the non-linear mixing.

Electronic musical instruments tend to have numerous degrees of design freedom, and this digital instrument has even more over the analog variety. It's this space that I feel could benefit from further exploration. But if one ends up with something fundamentally different looking and feeling to play, what are the ramifications? Players and audiences at a minimum expect rods and loops, so there's understandably strong resistance to changing these features, and a digital instrument fundamentally benefits from plates (increased SNR).

Let's Design and Build a (mostly) Digital Theremin! (by JPascal)

dewster: What am I blind to, what early decisions did I (and others) make that might be holding it back? What's the ultimate Theremin? Perhaps there's no single answer, but it's likely that there are better configurations waiting to be found. Browse Art PrintsHow much expectation is driven by simple adaptation and familiarity to what's available?

That task is an approach used in the design thinking method. Your fundamental decision was to build a digital theremin and focus the human-machine interaction on the familiar way of playing. To achieve this, you aimed for absolute linearity, built most FX and other effects into the device, and added a pitch display. This concept clearly struck a chord with all the professional artists: reliable, stress-free, and offering all the possibilities of the playing style they’ve mastered so far.

The main difference to Lev is, he analyzed all possibilities essentially without reference to earlier developments; his ideas extended as far as polyphonic instruments and so on. In doing so, he had already optimized key aspects: the frequency range, the antenna shape, the length and thickness, as well as the spacing between the antennas. Even during the first performances, he experimented with influencing overtones using filters in the HF range, etc. His technique differed from that of Moog instruments in terms of heterodyne technology too, thereby laying the foundation for later developments.

Let's Design and Build a (mostly) Digital Theremin! (by dewster)

LCD Dimmer (take 3)

I took another look at the LCD backlight dimmer circuit and finally settled on this:

Changes:
1. Lowered the filtering RC impedance.
2. Added R5 (100 Ohm) and C3.

Both of these changes were due to my worrying that the strong electric fields might influence the circuit. On the bench I noticed that my finger touching either lead of R5 caused the LED to light, so it was a relatively high impedance point, and C3 fixed this.

Let's Design and Build a (mostly) Digital Theremin! (by dewster)

Tyranny Of The Familiar

https://www.externaldesign.com/tech-tyranny-of-the-familiar/

Constraints channel creativity, and those constraints are formed from very early decisions that - in the larger scheme of things - may or may not be all that ideal. After the fact, it's hard to see beyond the mountains that get built on them. For this project I sometimes wish that I could find a musical / technical person paradoxically raised in a cave, to evaluate it with a clean pair of eyes. What am I blind to, what early decisions did I (and others) make that might be holding it back? What's the ultimate Theremin? Perhaps there's no single answer, but it's likely that there are better configurations waiting to be found.

How much expectation is driven by simple adaptation and familiarity to what's available?

Native Flutes presets (by Moon)

Hi,
I would love to have some native flute presets for my Theremini, like for instance, the Duduk. Can someone help me with this? How can I create it? Or are there downloads available? There is a list with all kind of presets from different people, but none of the links work!!

Headphones (by Tacodreams)

Hello everyone. I am new to the theremin and would like to try using headphones. I only play for myself at home and have no idea what I am doing. I have an OpenTheremin v4. Can I plug headphones directly into the theremin or do I need a mixer or headphone amp or something in between? Is there anything I should be looking for when purchasing headphones? Thank you in advance for any advice!