Why Can’t My Theremin Sound Like a (mostly) Digital Banjo?

Posted: 7/8/2018 7:29:16 PM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

The theremin as a musical instrument must play a tune and express something uniquely beautiful or it is nothing more than a gesture noise controller.

I remember how fun my first theremin construction was. It sounded like a mouse getting its nuts squeeze off. But I was proud of what I had accomplished and took the board to work to demonstrate to friends how it had a six inch proximity field. I stood up and told Brenda to peek over my cubicle wall to see my theremin I just pulled out and she slapped me… oh no you did not experience it yet.

I always say before you buy or build a theremin design get a sound sample so you can judge if that is the result you want, everyone is a expert. As a programmer of 40 years I have nothing against digital, it is when trying to find a solution to something on the internet and some people have a need to fill google with page after page of nonsense that does not work or just doesn't do what they describe. Theremin design info online is the same way.

Below is my evolution in sound after I moved beyond the mouse's balls and achieved an ideal sine-wave. All of the clean sounds below come from slightly distorting a sine wave. I rarely used much reverb so I would not mask the results of my sound for future reference.

From the theremin mouse sound to a fat voice is only separated by a thin veil of knowledge, nothing exotic. The vacuum tube has a slight advantage here but not enough for the extra effort over a transistor. It seems to me if an engineer only Models stuff then they usually do not discover much that is original. Exploration of modern electronics has become more like plug & play instead of bench testing and hours of research. IMHO


I am tone deaf (amusia), musically not able to distinguish tunes.

More of a sine wave

sine wave enhanced by even harmonics

The sine wave is starting to develop

Nice $10 Cello effect if you get it right, otherwise a pain in the ass.

The throaty sound comes from slowing down the sine roll over.

With skill and nice equipment by Coalport, what only a theremin can do.

In this image the banjo is the instrument the theremin does not mimc.

Edit: Some people will only see problems in the theremin, I focus on her fun and natural beauty, like Lev Sergeyevich experienced and enjoyed.

Posted: 7/8/2018 8:30:49 PM

From: Northern NJ, USA

Joined: 2/17/2012

Metal detectors (the flip side of Theremins) necessarily evolved quite quickly due to practical demands, the war effort, etc.

The only reason analog Theremins still exist is because they hit an incredibly efficient technical sweet spot of doing a whole lot with almost nothing, so anyone with a few tubes / transistors, a few OK coils, and enough gumption has, can, and probably will built one.  Some will go further to experiment / science the shit out of it, add some more actives and passives, and end up with something fairly playable.

But look at what all analog Thereminists still, to this day, have to deal with: 

1. Cramped, quasi-linear fields;
2. Timbre change tied to oscillator coupling / meowing (see #1);
3. Excessive Drift;
4. Difficulty tuning / aligning / owning the damn thing;
5. External "talking box" and other effects just to get a decent or human tone;
6. Sluggish external tuners;
7. Pitch preview wheedling in your ear as the only viable, responsive playing aid (see #6);

I could go on and on.  For those reasons and more I never warmed up to my EW, and the Theremini (advertised on Amazon as a "Digital Theremin" - which I agree with, though it is very poorly implemented, particularly so by Moog Inc.) is a $300 joke.

I didn't make the world, but like it or not the distant past is analog, and the recent past, present, and future was/is/will be digital.  Old shit is quaint and often can have a lot of instructional value, but it's way past time for Theremins to grow up.  

Posted: 7/8/2018 10:06:55 PM

From: germany, kiel

Joined: 5/10/2007

Aaah ja..

Posted: 7/8/2018 11:44:28 PM

From: Northern NJ, USA

Joined: 2/17/2012

Sorry DOMINIK, not aimed at you (by all accounts your Theremins are quite nice).

OK, I make a solemn promise (to TW and myself) to never reply to anything Christopher posts ever again, even obliquely.  Life's too short to spend it feeding trolls and playing their stupid head games.

Posted: 7/12/2018 3:33:36 PM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

To my friends in Houston building around the Kustom Design I wanted to mention something on thermal drift or the final sound so you do not get caught up in theremin myth and non-sense. As can be seen in my picture below my fixed and variable pitch oscillators used readily available IF transformers operating around 900 kHz. I always build in a modular fashion so sections can be easily replaced. There is little critical about the RF oscillator frequencies and no magic in coil size when it comes to a good authentic theremin sound. Using a higher RF frequency does have advantages. My hybrid tube design had little or no thermal drift using optical tuning, which pitch drift is something inherent with transistors. Your initial goal is to achieve a good audio sine wave after mixing, as all sounds evolve from there. Then you can make the sound a bit nastier to satisfy your taste.

This theremin sound is from these two boards below, it is a bit of a trick in how this sound comes about and was something Lev Sergeyevich discovered. I figured it out years later. It can be done reasonable well with transistors also. The green terminal at the very top of the board is for my optical tuning instead of a variable capacitor, so the pitch tuning knob can be anywhere, or even ten feet away.

If you want your theremin to sound like a banjo then digital is the best way to pursue this and any other unnatural controlled triggered sound.

Some misguided call anything a theremin, even a cell phone app, so I guess you can also call anything music.

