How can I reproduce the Theremin sound on the Mopho x4?

Shalom everyone,
How is everybody?
I had a question I got a MoPho x4 around December last year and now I'm trying to create a theremin sound.
Last night I set oscillator 1 to a square wave and pulse width set at 65. I set the glide around 123 think which gave close to a theremin sound and set the filter Frequency to 90 and Resonance to 63 which sounded close to pure sine wave. But was wondering if can be better and if anyone had some suggestions?
 
Thanks
Marcus

Sound on Sound's website seems to be down currently, but I used this article to create a pretty convincing theremin sound in Z3ta +2. You should be able to glean enough info from the article to create it on your device. I think you'd be better off starting with a sine wave, instead of a square wave. 

There is no sine waveform on the MoPHo x4, The waveform it dose have Saw tooth, Triangle, Saw-Triangle, Square.
I read the article a couple of times and try to follow it but little hard with no sine waveform.
I did find a preset on Arturia Micro brute http://severed.garden/synths/microbrute-patches-synths/theremin-sound-with-microbrute/ it work a little with the MoPHO x4.
 
Thanks
Marcus

The Mopho's filter gives a pretty good "fake" sine wave when self-resonating. Switching off the oscillators and using the filter as the sound generator gets somewhere in the right direction. If necessary add just enough oscillator (or noise) to trigger the filter into resonance with the filter frequency being keyboard controlled.

Convincingly emulating a theremin using a conventional synth isn't entirely straightforward. There are some very distinctive things about the theremin besides its wave forms. In particular the way the start of notes are nearly always not quite spot on pitch even when the instrument is played by an expert, and how pitch and volume interact seamlessly and smoothly.

The smoothness means that any MIDI controlled synth isn't easily going to get there because of MIDI stepping - despite being analogue, the Mopho is entirely MIDI controlled.

Carefully using slide and portamento helps, as does using free-running LFOs set to sine/triangle waves to very slightly and slowly modulate pitch and volume to introduce a hint of random behaviour, along with another pair of LFOs used to generate deliberate vibrato and tremolo.

I'd suggest setting the filter and VCA envelops to an "organ" kind of setting, zero or near zero attack, delay and release. Maybe use the Mopho's third envelope to slowly introduce vibrato/tremolo rather than using only the mod wheel.

The more controllers you have available, the better and fortunately the Mopho has lots of modulation possibilities. Don't be afraid to record the basic track as MIDI only then go back over it recording further controller movements into the MIDI before finally recording the synths audio output.

The little Korg Monotron can produce pretty convincing thereminish kind of sounds, especially with some added delay and chorusing. The ribbon controller is a bit fiddly, but it can swoop around very nicely. Particularly good at Tim Blake (Gong/ Hawkwind) style swoops and burbles. A more expensive approach is to use a synth like the Dark Energy, the (discontinued) MFB Nanozwerk or any synth with voltage controlled filter/pitch and a ribbon controller.

Sure, you could buy a theremin for around the same money as a synth plus ribbon controller, but the synth/controller route has the huge advantage of not having to learn to play a theremin :-)

I'm not at home so I can't test things using my Mopho, but off the top of my head use the Mopho's filter knob to sweep filter pitch if you're using the filter as a sound source. Pitch wheels tend not to be assignable to anything else but oscillator pitch.

And no, filter keyboard tracking is rarely spot on through the whole range.

My fake theremin is a Doepfer ribbon controller and a Nanozwerg. Using control voltages rather than discrete MIDI values makes for a swoopy and smoother out-of-tune-o-phone. I keep thinking that one day I'll get a theremin, but the more I've talked to good thereminists, the less I've felt up to facing that learning curve.