Pro Level Moog Theremins

"I wonder if professional thereminists wouldn't prefer an instrument with less functions but with better music inside. " - Thierry

I dont believe the two are in any way mutually exclusive.. In fact, to craft the sound in a controllable way, I do not see a way that "less functions" can facilitate this - I do agree that true genius is managing to get the functions from a minimal system - I am not a true genius! ;-) ... But even the best theremin on the planet does not have a way for thereminists to configure the sound to exactly what they want - they have "their sound" - effectively pre-defined by the developer,  adjustable in limited ways, but not at all adjustable in terms of the 'core' waveform.. You cannot get the same sound from a diode mixer as you can from a 4Q multiplier, or vice versa - but if you have both a diode mixer and a 4Q Modulator in your instrument, you can get both,and can mix them together to suit your taste ;-)

"I fear that if you don't take these thoughts into consideration, you risk to run into the Theremini effect : Lots of functions which will make untalented players think that these will allow him to be a virtuoso, but the true musician will perhaps not appreciate this engineering genius."

I dont think my theremin (if it ever gets to market) will have any appeal whatsoever to the theremini crowd.. It doesn't have anything (other than adjustable linearity and span ;-) to "assist" morons in playing the instrument - It doesn't have any visual pitch display (sorry Dewster, this isn't a dig - ;-) there is nothing gimmicky - no pre-recorded RCA's or UFO pads..

Apart from which, it will be much more than twice the price of the M-ugh toy! ;-) even a complete board will not be less than twice the theremini price, without cabinet or fittings.

As for being recognized as a genius by musicians ;-) - That is something of an extremely foolish notion - They dont care if there's a 555 inside that they are paying £500 for, as long as it does what they want... Over drive a cheap LMxxx audio amplifier to soft clipping and you can be worshiped for your technical genius!

Nah, in this industry, the real genius is someone who can sell a couple of transistors for £50 and have happy customers! ;-)  Occasional recognition from other engineers for genuinely clever ideas means a lot more.

Fred.

PS Thierry, notice I said "whatever else". So it doesn't have to be an EPRO.

Many thanks for your kind wishes, Philip;-)

The core principle of my scheme is really simple.. Imagine a pitch oscillator with a voltage input that changes the frequency just like the antenna capacitance does.. So if this oscillator is left without the voltage control connected, it will be a normal pitch oscillator.

Now take the output of this oscillator to a circuit which compares its frequency to a reference frequency, and provides an error voltage - feed this error voltage back to the oscillator, and the oscillator will lock to this reference frequency (its frequency wont change as the player waves their arms about, it will always stay at the reference frequency)

What will change as the player waves their arms about, is the error voltage required to keep the oscillator locked to the reference..

If one then took this error voltage directly to an identical oscillator which didnt have an antenna, this oscillators frequency would vary as the player waved their arms about!

But the reason for doing this, the advantages this confers, are as follows:

Your pitch antenna is only radiating a single frequency

You can modify the error voltage going to your pitch oscillator, so you can scale it to cover any range of notes you want

you can modify the error signal in non-linear ways, so you can shape the linearity however you choose.

You have complete control without losing anything of the theremin.. you have the same signals for heterodyning, and you could build quite a simple theremin based on this topology..

But instead of a simple theremin, I have once again gone for a monster ;-)..... Oh, there's a part of me pulling towards perhaps making a simple version first..

But the trouble with doing that is that I want waveform to change with pitch, and I want formant filters - because I know these are the only way to get the sound crafted to perfection.

Fred.

Feeleep,

Just probing here..

When you mentioned EWP - what was/is it about that instrument that attracts you most? - Is register switching and linearity what you are after?

I am, following the above, wondering what sort of cut-down version of my board might be of interest - For example, If I was to sell a board at say £150 which gave register switching and good (adjustable) linearity and adjustable span, and output a set of audio waveforms (and had a VCA wired to the volume circuits) but the buyer was left to build all the analogue stuff - filters if they want them, audio mixer or selector switch if they really wanted basic, preview amplifier etc) would this be of interest?.. Or perhaps a board which was a basic switching theremin, but could be enhanced by adding more audio circuits?

I am wondering if I could do my theremin, which will be 2 boards anyway, as one board containing enough for a simple stand-alone instrument without digital editing, and the other being the advanced audio stuff and the editor / preset board... My design is on those lines anyway, but I hadnt really thought about having them as independently operational..

Im not really sure I could make one board do a complete usable stand-alone theremin - the first board is heavily packed with RF stuff, but I am at the stage where if its possible, now is the time to do it that way - and I would only do it this way if doing so wouldnt compromise the complete instrument in any way.

At present, looking at my block diagram, blocks 11 and 12 are on the 2nd board - Moving block 11 to the first board would be difficult (probably impossible), and its one of the most expensive and vulnerable  blocks, containing the analogue register multipliers and mixers.. But block 10 is the 'digital' (its not actually digital, its mixed signal - a more advanced form of what the EWP does) heterodyning, - adding a small board containing filters and a VCA, one could get a theremin from board one which has adjustable waveforms, but no "true" fully analogue waveforms... These waveforms are, however, far better than those from the EWP - The EWP only has a triangle wave which is distorted to give its sound - my mixed signal heterodyning gives ramp, 'rectified' wave ramp, triangle, and pw adjustable square.

I will need to prototype this board anyway just to check this section out, so will have a layout done - If I keep the possibility of this board being put into production as an add-on, this is work I shouldn't need to do again.. And if someone later wanted the full theremin, this board would be redundant, but will be replaced by the comprehensive audio board.

Hmmm ... I am glad you started this thread!  ... A couple more weeks and these options may not have been available.

Fred.

Sounds like you're describing a phase-locked-loop circuit (PLL) used in synthesized radios using a VCO (voltage controlled oscillator).

All I am looking for is the sweet HOLY GRAIL sound we all talk about but unfortunately most can ill afford. I know of one fine RCA example with speaker that is easily into 5 figures.

Mark Kepp designed a small tube theremin based on his Mark 1 but I do not know how it turned out sound-wise. It used miniature tubes. Straightforward three-oscillator design..

Mark still is not 100% from his near-death experience.

Any kit would need to have any SMD stuff already installed. Pre-stuffed boards would reduce the amount of folks calling and saying "my theremin doesn't work, please help me!!" Of course that ups fabrication costs to you and end cost to the customer.

"Any kit would need to have any SMD stuff already installed"

Oh yes! - SMD is the curse for DIY constructors or small (large ;-) ? developers .. There are loads of new chips only available in SMD which I cannot use.

And this is where Cypress Semiconductor has scored big time, IMO - they put their PSoC4 onto a small breakout board which also has other SMD fitted and sell these at £4

This is what kick started me again, because its a fast mixed signal configurable device, having op-amps, comparators, IDACs, programmable logic arrays, loads of other stuff and a (in my application, hardly used) 32 bit ARM processor.

I wish other manufacturers would catch on to this idea! - Yeah, have SMD - but also supply the parts on 0.1" breakout boards at a little higher cost.

"All I am looking for is the sweet HOLY GRAIL sound we all talk about but unfortunately most can ill afford. I know of one fine RCA example with speaker that is easily into 5 figures."

So you would, if you found a sound that for you was authentic, be happy to have just that sound? - If you had a board with say 16 presets you could adjust, and the option to wire any of these presets to control potentiometers if you wished, and you could get the sound you want (given instruction on what qualities each preset alters) be interested?

I believe that the adjustments needed for a 'classic' RCA sound can be achieved with fewer presets - one needs the waveform to change with pitch, particularly at the bass end, where it gets really rich in harmonics and quite 'gritty'... And one needs this waveform to go through a series of fixed band-pass filters (formants) - fixed as in they dont change as pitch changes - but they need to be adjusted to initially craft the sound. One also needs some harmonic variation as a function of amplitude - this is the one thing I am not confident or sure about, I need a load of samples from a Lev theremin at different frequencies and different amplitudes. Then I believe adding audio FM gives qualities that I feel add "authenticity" - and this is one of the mechanisms of distortion I think tubes do naturally (microphonics) which solid state doesnt.

But its probably best if I stop talking about this stuff - I am interested in any ideas you have about what you want though.. However the subjective nature of "the sweet HOLY GRAIL sound" makes pragmatic discussion of this matter dangerous!

Have you ever heard any 'mere mortal' get "this" sound from an RCA today? I dont think I have! ;-) Damn close, and a few thereminists can play well enough that one hears something like what one hears from Clara or other revered recordings.. But I am fairly sure that even a perfect replication of the RCA sound, in terms of waveform and formants and dynamics, would still lead to disappointment if not coming from an RCA!  Simply because by believing its an RCA/ Lev theremin the expectation will be that it sounds like a Lev theremin and has an "authentic" sound. Personally, I dont believe there is such a thing as the "authentic sound" - I think every Lev theremin and every RCA sound quite different to each other ;-)

Fred.

One of the problems is that the playing technique, especially the transition between tones, vibrato, and the left hand tone shaping has more impact that one thinks.

Clara Rockmore's Lev built custom instrument sounded lovely under her hands. But it sounds rather annoying and non-brilliant when the new owner, Dalit Warsaw, plays it. Same thing for other models, compare Barbara Buchholz and Lydia Kavina playing the same tVox, or compare Carolina Eyck and Thomas Grillo playing the same EPro...

"Clara Rockmore's Lev built custom instrument sounded lovely under her hands. But it sounds rather annoying and non-brilliant when the new owner, Dalit Warsaw, plays it. Same thing for other models, compare Barbara Buchholz and Lydia Kavina playing the same tVox, or compare Carolina Eyck and Thomas Grillo playing the same EPro..." - Thierry

Thierry, this is something that I have moved a long way to agreeing with you on ;-)

I had a clear differentiation between "playing" and "sound / tone" in the past, and thought in terms of good playing 'complementing' a good sound..

But I am more inclined now to accept that you cannot separate the two - a "crap" waveform can sound ok when played by a skilled musician, and a "great" waveform (and IMO there is no such thing as a perfect waveform anyway - every waveform becomes tiresome or irritating if sustained without change for too long) can sound crap if played by someone who doesn't play well.

I suspect there are some sounds (those with musically conflicting components) which will sound horrible to any musical person regardless of how they are played, and some sounds which may be closer to the so called "authentic" theremin sound espoused - There are sounds with more string qualities, some with more vocal qualities, some which can only sound ok in the hands of a master, and some which can sound "ok" in the hands of a novice..

But any "magical" or "mystical" qualities do not, IMO, come from the raw waveform/s, they come from the way these waveforms are 'crafted' in real time by the player.

And this is IMO the greatest offense of the theremini - its latency completely prevents any possibility of real-time "crafting" (or even playing) - if one had a wave-table theremin which was instantly responsive so that the waveform updated much more rapidly than an audio cycle period, then I think the "search" would be over - I think one could then capture (sample) the classic theremins and skilled players could play these - and that such an instrument, loaded with samples of Clara's instrument, played by Clara, would have all the qualities of her playing her instrument..

Alas though, we will never be able to test this conjecture.

Fred.

Interesting phenomenon. I wish you luck, sir. And thanks for posting replies.