WANTED: Midi Theremin

Posted: 11/24/2012 3:14:08 AM

Joined: 11/24/2012

Hello, I am a EDM producer new to the theremin world :-). I am looking for a theremin that can also be used as a midi controller. I understand that it may not function as well as a keyboard controller but all that I have really found was this gentlemen:



Is there others out there or something better for what I am needing? any advise or direction would be greatly appreciated!


Posted: 11/24/2012 11:40:43 AM

From: Canada

Joined: 8/1/2008

The only professional level MIDI theremin ever made is the Moog MIDI Ethervox. The HORST MIDI WAVE (above) has been around for a while but I don't know of anyone who owns or plays one. 

Have you considered getting a peripheral MIDI converter and using it with a conventional theremin? WAVEFRONT TECHNOLOGIES makes a CV to MIDI converter that might provide what you want.

The problem with MIDI theremins is that MIDI receivers are not built to be used with continuous controllers. They are designed for keyboards that send note on/note off signals. The MIDI Ethervox (in CHROMATIC MODE) has programmable scale and arpeggio note on/note off capabilities as well as continuous control. Moog only made about 50 of these instruments back in the late 90's, they don't come up for sale very often and when they do they are fairly expensive. 

Exactly what is it that you want to do with a MIDI theremin? Are you a precision player, or is the instrument to be used for "experimental" music and/or FX?

Posted: 11/25/2012 12:07:28 AM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Other than the Moog Midi Ethervox, I know of no good MIDI theremins -

One can get Pitch to Midi converters (both as physical devices and software) which can go some way towards achieving MIDI output from theremin audio input - And one can take the CV output from a theremin like the Moog EW+, or a Moog EW with pitch to CV board fitted, into a CV to MIDI converter (I have used the Novation Bass-Station Rack, which has an excellent CV to MIDI converter built in).

Theremin audio is usually low in harmonics and well suited to pitch-Midi conversion - but one must keep the physical constraints in mind.. At least one (usually 2) cycles of audio are required before the converter (whether pitch-Midi or pitch-CV) updates - this means that latency increases the lower the audio frequency is - Most, if not all conventional converters lose sync below about 100Hz, so one needs to tune the theremin higher or play in the higher registers (one can shift the CV or MIDI down so that the equipment one is driving plays a lower note).

One needs a constant audio level to the converter for adequate performance (as signal level drops, the converter loses sync) - So one needs to take the output for the converter from before the VCA - This problem is overcome if one uses the EW+ CV output, as this is derived from before the VCA.

Jaycar sell (or at least did at one time) a Silicon Chip MIDI theremin - I have not seen this, and have not heard any reports about it - it is based on the standard Silicon Chip front end, but has no reference oscillator or heterodyning - the frequency variations in both the pitch and volume oscillators are converted directly to control voltages, and these feed a PIC microcontroller which converts them to MIDI signals. This approach overcomes the problems and latency involved in converting audio to MIDI.. But I have no idea about how linear this instrument is, what its output format is, or any other details (I bought the article from Silicon Chip, but was never able to download the firmware, so got a refund - Check that a programmed PIC is supplied with the kit if you buy one!)

The only details I have on this theremin are these:

http://wildchurch.com/mtcd1.jpg  - Block Diagram

http://wildchurch.com/mtcd2.jpg - Analogue front - end

http://wildchurch.com/mtcd3.jpg - Digital

http://www.jaycar.com.au/productView.asp?ID=KC5410 - Jaycar back catalogue.



 Oh - The S/C controller cannot be used as a stand-alone theremin.


Posted: 11/26/2012 3:11:48 PM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Here are some more CV to MIDI units I found - Again, I have not used any of these, and cannot say anything about them:

http://www.schneidersladen.de/en/analogue-solutions-cv-to-midi-2  2xCV Note and Velocity - assembled rack unit, 100 euro's

http://midikits.net23.net/cv2midi/cv2midi.htm - CV to MIDI unit claimed to be compatible with EW  45.00 euros

http://www.woodbrass.com/modulaire-trig-et-cv-doepfer-a-192-16-cv-to-midi-p124548-af833.html Doepfer A-192  117.00 euros

The only unit I have had any expierience with is the WaveFront - And I certainly would not recomend this!

None of the above units, as far as I can see, are really suited to theremins - Most (if not all) take an input voltage and convert this to a single MIDI stream.. I do not see any which split the input into Note on/off AND Pitch-bend streams.. It may therefore be possible to get either note data or bend data, but not both..

To track the pitch using bend data, one would need a reciever capable of interpreting the 14 bit stream and processing this correctly - Assuming linear CV / Input values (equivalent to 1V/Octave) and 7 octaves divided into this 14 bits, each step would be nearly 2 cents.. To get 1 cent resolution you would need to scale the reciever to interpret the pitch bend command (range) as  3.5 octaves (you may just get away with +2/-2 octaves).. But you would be severely limited in terms of MIDI instruments capable of doing these 'transformations' and would probably need to construct or modify your own software synth using one of the available DIY programs such as http://www.synthedit.com/ - (I think there are some open-source projects as well, but this is not an area I know anything about)

One needs volume CV to be interpreted, and most units assign this to the note-on velocity - which is useless for the theremin - this data needs to be streamed in real-time as CC data. then one still needs (unless one designs ones own synth which doesnt use this) Note-on/off messages.

As Coalport said - It all depends on what you want to do..

If its just Note-on/off you want, the above interfaces may suit your purposes.


(for EDM, the Horst might be your best bet actually - You arent actually looking to play a theremin melodically, are you? - )

Posted: 11/26/2012 7:12:27 PM
randy george

From: Los Angeles, California

Joined: 2/5/2006

Hello fortaymusic,

If you have a Mac or PC with Audio Interface with a Digital Audio Workstation (Live, Logic, Cubase, etc.) and experience with audio/midi software,  then I recommend -> MIDI MERLIN. you may have to try it out before knowing whether it suits your requirements. I wrote the software and it is available for free. 

visit this address :    http://cycling74.com/project/midi-merlin/

there are some demo videos on the facebook page:   http://facebook.com/midimerlin

or search on thereminworld for a detailed post I wrote a few months ago.

MIDI Merlin has a real-time audio-to-midi engine that has unmatched accuracy and timing of monophonic instrument input conversion.  the only requirements are that you must use a computer, and you must have knowledge in the area of DAW applications, MIDI, you must own an audio interface, and you must experiment with settings to get the best results. the only downsides are that the conversion is only chromatic, and there are no filters for conditioning the input, so a poor input signal quality will almost always yield false note output.

MIDI Merlin does not convert incoming pitch/amplitude to continuous MIDI CC messages or 14-bit MIDI pitch bend data. If you are specifically looking for this functionality, contact me, and maybe I can create something (based on MIDI Merlin's tracking engine) for a reasonable fee.

if you have questions you may contact me at:  midimerlin [at] randygeorgemusic (dot) com


Posted: 11/27/2012 12:24:41 AM

From: Canada

Joined: 8/1/2008

Hi Randy,

MIDI MERLIN is truly brilliant! That's not surprising...I would have been surprised if it hadn't been brilliant. Is there a demo of the program being used with a theremin? How does it respond to a continuous pitch controller as opposed to an instrument (like a guitar) that plays discrete notes?

Posted: 11/27/2012 3:39:07 AM
randy george

From: Los Angeles, California

Joined: 2/5/2006

Hi coalport,

MIDI Merlin does not currently output high resolution continuous pitch. It has two modes of Audio-to-MIDI conversion... momentary and continuous.  in both modes only note-on/note-off messages are generated based on when the input signal falls within a range of 50 cents from the note frequency center, and when the amplitude is above a certain threshold. essentially quantized to the chromatic MIDI note scale.

In the momentary mode, when a custom assigned key or MIDI mapping is pressed, the MIDI note-on message for the nearest tracked pitch is engaged. releasing the key, generates a corresponding note-off message.  with a midi instrument and theremin signal being monitored simultaneously, and with the high speed/precision of the on-screen tuner window, the program becomes a powerful aural skills/muscle memory building tool. 

In a future version, (pending I get a boost in enthusiasm for programming again)  I could add a continuous pitch control tracking mode, where 14-bit pitch bend data (with a target bend range of only one semitone) could be generated along with the continuously triggered note-on/note-off messages... there are problems associated with automated pitch bend data though... pitch bend amount ( in semitones) is usually set on the MIDI controlled synth. also assuming a target range of one semitone, a note-on message would be generated every-time the incoming pitch is exactly one quarter-tone above or below a note frequency center. new note-on messages usually equate with re-triggered envelope... the synth would have to be configured use slide or portamento or have slow attack and quick release. .. or something to mask the constant re-attack of notes.

There are not yet any demo videos of MIDI Merlin and theremin...  sorry for this... it also requires enthusiasm and energy that I currently do not have at the moment.

Posted: 11/27/2012 4:11:41 AM

From: Northern NJ, USA

Joined: 2/17/2012

A digital Theremin could generate MIDI data almost trivially. The problem (as randy george describes) is with the discontinuous nature of MIDI pitch, and particularly with volume envelopes.  MIDI really needs an update (higher baud rate, single cable bidirectionality, audio channels, etc.) but good luck getting manufacturers to further commodify their products.  MIDI was hatched when keyboard development was more egalitarian, and I fear those times are long gone (now that any random marketing "expert" or MBA can trump our very best engineers - do I sound bitter?).

Posted: 11/27/2012 6:58:18 AM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

" MIDI really needs an update (higher baud rate, single cable bidirectionality, audio channels, etc.) but good luck getting manufacturers to further commodify their products." - Dewster

MIDI is too slow, as you say - There are other interfaces / protocols being used for music data - one of the simplest is MIDI over USB, here one can stream multiple midi "ports" at high speed, the driver in the PC "sees" these as independent MIDI ports, and it is possible for example to have pitch CC messages being streamed continuosly to one port, Volume CC to another, etc..

None of which helps you to drive any MIDI instruments however - the only way to get the MIDI data to play a synth is to stream this data to a software synth specifically created to accept it.. It does however allow one to accurately record a theremin performance in MIDI form.

"In a future version, (pending I get a boost in enthusiasm for programming again)  I could add a continuous pitch control tracking mode, where 14-bit pitch bend data (with a target bend range of only one semitone)" - Randy George

I am puzzled by why the bend range is limited to one semitone - I have MIDI gear which happily accepts +/- 2 semitone bend, which gives a perfectly acceptable 1/10th cent resolution.. I agree that going lower resolution than this starts to become audible (produce zipper type effects, particularly as the MIDI update speed is slow)

I personally do not think that single-port MIDI is of any real use with theremins - I also think that, for any digital control data sheme to be useful with theremins, it will require "reciever" instruments specifically designed or adapted to take theremin data.

What one (IMO) really needs is theremin with multiple input and output MIDI ports, and probably a USB port (Or alternatively only a USB port "emulating" multiple MIDI ports) - And one needs "reciever" instruments which accept these multiple MIDI ports and behave in a different way to conventional MIDI appliances - In particular, "Note-On" must not "retrigger" anything, it must simply update the pitch against which bend data is referenced - and volume would be determined soley by CC messages. If the Note-on/off (perhaps with a snapshot value of the volume value embedded in the velocity data) was sent one one port, this could then be directed to any standard MIDI gear..

The "transmitting" theremin should ideally be able to replay the data it sent. With the above scheme it would be possible to use MIDI recording / sequencing software without modification.


Posted: 11/27/2012 8:23:50 AM
Jesper Pedersen

From: Iceland

Joined: 3/10/2012

A really great alternative to MIDI is Open Sound Control (OSC) that uses modern network technology: http://en.wikipedia.org/wiki/Open_Sound_Control It is very fast and ultra flexible and would be perfect as the communications protocol in new theremin projects.

Regarding the MIDI pitch bend. In my experience it is the synthesizer or sound module that interprets the incoming pitch bend data and maps it to a specific pitch range e.g. ±2, ±12 or (depending on make and model) even +2 -12.

Originally MIDI pitch bend was a 7 bit message just like CC but it was changed to 14 bit for a much higher resolution.


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