Basics of how the EW-Pro works.

What I am about to disclose has a high risk for me – I fear that I will lose a few friends by doing this - and I may even become reviled by many in the Theremin community.. But I cannot stay silent any longer.

I wrote on the “Etherwave Pro ??” topic [i]“But I do not think disclosing the Epro 'secret' would advance science, engineering, Theremin development, or the interests of Epro owners at all”[/i] – but I now, after much thought, and some discussion with another person who is “in the know”, think that I was wrong on this.

In fact, I now wonder if Bob Moog deliberately “hid” the secret as a means of delaying its disclosure (which he MUST have known was inevitable) for long enough that the E-Pro would become established as a revered musical instrument, and, when its modus operandi was disclosed, this would shatter once and for all the bogus assertions made by many regarding the use of simple digital technology in musical instruments.

Unfortunately, I was one of these people – I regarded analogue as sacred, I believed that any “true” Theremin needed analogue heterodyning of the actual waveforms from the pitch and reference oscillators, or from something that effectively tracked and duplicated these waveforms at multiplied frequency ratios (my strategy for my ultimate Theremin) – To me, these waveforms, carrying their varying harmonic contents (due to oscillator interaction mainly, but, I believed, also due to subtle interactions with other fields), is what really made a genuine Theremin sound.

I was embarking on obtaining (hiring or borrowing) an E-Pro with the idea of producing a Technical Reference Manual for it .. Through discussions about this project, I got one Theremin Engineer to disclose the E-Pro “Secret” .. What I learned stunned me – I have admired Bob since I was about 14 – I have read everything from and about him I could, I spent my pocket money obtaining copies of his patents (which, in the days before the Internet, and living in South Africa, was not easy or cheap).. I learned analogue electronics from Bob – He, and the Synthesizer, were the reason I got into Electronics.. Yes - its stupid - but I felt betrayed.

I got hold of an E-Pro to verify what I had been told – And discovered that it was true.. Alas, my disgust and disillusionment (which I now realize was due to little more than irrational prejudice against using CMOS logic to produce sounds) caused me to abandon extensive examination of the E-Pro.. I had seen its secret, and its secret jarred against everything I believed about music technology – This was a sad, gut reaction mistake.. I should have looked more carefully beyond the tone generation stage, and at the wave-shaping and filtering sections – as these (I later realized) must be where the magic resides.

I must admit that, before I learned the 'secret' I did not like the tones I had heard from the E-Pro.. My interest in it was focussed on its linearity and range switching, and think this biased me away from further exploration - but since that time I have heard some wonderful tones from it - particularly from Peter's performances.. He seems to get the best from this instrument - for example in his "lemminkainens dream" - so I now really regret my predudice.

Here is a brief synopsis of how the E-Pro works.. More specifically, how it achieves its range switching, how it produces its CORE tone, and how it improves pitch linearity.

1.) The oscillators are conventional and analogue
2.) The waveforms from these oscillators are squared – they are converted to ‘digital’ signals and lose any 'relevant' or 'natural' harmonic data they may carry
3.) These squared oscillators signals are then fed to standard CMOS logic circuits – dividers, multiplexers etc.. Both oscillator frequencies are divided and the square waves from the selected pair of dividers (selection being controlled by the range switch) are fed to a CMOS XOR (Exclusive Or) gate.<

Fred Asked:

BUT – What would people have said if he [Bob Moog] had disclosed these facts when the E-Pro was launched? “Our new Pro Theremin uses CMOS Dividers and digital heterodyning based on a CMOS XOR gate” – LOL!

****************

Well Fred, I don't know what others would have said, but I would have responded with, "I don't care if Bob makes a theremin that produces its sound by sticking Lilliputians with hat pins. If I like it I'll buy it."

Are you aware that the SERIES 91 theremins are not heterodyne instruments at all? They are gestural CV tone generators.

I think that these are considerations that are of interest to engineers but are of little concern to musicians. Since instruments are bought mainly by musicians, the impact of technical specs on sales is probably negligible.

There were apparently some innovations involved with the Etherwave Standard when it first came out but Bob did not patent them because the patent process is slow, expensive, and he felt that the market probably wouldn't justify the cost. He went ahead and manufactured his Etherwave kits without the protection that a patent would have offered. Sure enough, within a very short time, people were marketing knock-offs using what was essentially Bob's Etherwave design.

Forgive me, since I'm talking from a position of complete technicial ignorance when it comes to the implementation of individual theremin models, what with only having the one E-Standard.

The only reason I took interest in this thread was the slim hope of being able to aquire a E-Pro clone from someone. :P

But as coalport said, [i]"I think that these are considerations that are of interest to engineers but are of little concern to musicians."[/i], and I definately fall into that category. Like many other things, the implementation details just aren't important to an end user if it does the job and you're happy with the result.

But I can't help but think "... that's it?". That's the big secret? Given the level of secrecy there appeared to be around it, I was expecting it to use the still-beating hearts of small children or something!

But the "reasons" that FredM suggested for the secrecy, I can understand. I know people who claim to be able to hear a difference using a gold-plated toslink cable! Everyone loves the placibo effect, whether or not they'd care to admit it.

So the idea that, as FredM said, [i]"People would have "heard" the "digital overtones", and pompous engineers like me would have spouted nonsense about the technical reasons for the instruments "inferiority"."[/i] seems perfectly reasonable to me and I would have assumed the same.

At the risk of asking "the same question again", couldn't Moog just stick the E-Pro boards in square E-Standard style boxes and just sell those? Again, as an end user, I don't really care what shape the enclosure is, though admitadly I do really like the design.

I can't help but think that doing that would more-or-less negate any need for anyone to clone it in the first place. Maybe the threat of "knock-offs" appearing in market may be enough to get them to do just that?

One can always hope. I just want a more linear theremin. :(

I can understand Fred's concerns.

1. I have seen plenty of instances of musicians involved in electronic music asserting as an article of faith the superiority of one particular technology over others. Some people love, for instance, tube amps with an almost religious fervour and persuading them that there are also equally good solid state amps is as unlikely as converting a creationist to an evolutionist.

2. As Peter points out, Bob Moog created a theremin which does not heterodyne. This is a fact often overlooked by those who attribute a special magic to the heterodyning process.

3. Lunetta techniques - using, or rather abusing, computer chips to process audio in ways not intended or imagined by the designers - are strongly associated with the lo-fi end of the electronic music scene - intentionally harsh sounds abound around lunettas. They are the bad boys of the digital world.

4. Moog instruments hold a special place in the hearts of some fans of old school analogue instruments. They find in them a richness and quality of sound not associated with any form of digital music.

5. There is most certainly a subset of thereminists who are (a) ardent fans of analogue tech and (b) believe in the magic of heterodyning. I can imagine that for them pre-knowledge of the techniques used in the etherwave pro would strongly taint their perception of the instrument, just as a fan of high performance cars would view a Lamborghini fitted with an engine designed by Škoda Auto with some cynicism. (In case this does not translate well, I mention that in the UK Škoda have a reputation for very poor quality cars.)

I imagine there are one or two people who, on reading Fred's posting, felt that it validated their preference for some other theremin.

Personally I am rather pleased that I had an opportunity a week ago to play extensively with an Etherwave Pro, before knowing how it worked could taint my perception. I still prefer the timbres available on the Standard, but the playability of the Pro in the lowest registers is spectacular, and for that I love it. This is directly attributable to the design of the electronics. That the timbres are a little too refined for me is irrelevant; I know plenty of ways of roughening them up in the effects chain.

And I should add that, as with Fred, my admiration for Bob Moog has gone up a notch, because he did something that for me was unthinkable. Literally. I chanced upon Lunetta tech a few months ago and posted some observations on this forum (http://www.thereminworld.com/forum.asp?cmd=p&T=4040&F=3&p=2) at that time - specifically how it made octave shifting very easy, while at the same time having absolutely no idea how the range switch on the ePro worked. It just didn't occur to me that he could have used that technology. (Even though I now see that Thierry had said (http://www.thereminworld.com/forum.asp?cmd=p&T=4221&F=715) as much back in September last year.) So when I learned how it works I had a real forehead slapping moment. "Of Course!" I shouted, "It's So Obvious Now I Know!"

This is a pain – my replies are vanishing into the Aether and not appearing ..
I will try again..

Coalport said:
[i]---------------

>> Well Fred, I don't know what others would have said, but I would have responded with, "I don't care if Bob makes a theremin that produces its sound by sticking Lilliputians with hat pins. If I like it I'll buy it."

---------------[/i]

I hope you are not the exception – and I hope I was wrong.. What I do know with certainty is that, when it comes to marketing, there are other established manufacturers of Theremins and theremin related junk, who use “true Theremin” and “analogue” and “coils” as synonyms for quality – and who berate designs built using “signal generator IC’s” and (ugh!) “CMOS chips” and for whom the E-Pro would be inferior to their two-transistor analogue heap of s***.
This “analogue, heterodyning and coils” test is, I think, quite ingrained in Theremin (and “Pro” audio) thinking.. It is genuinely believed by many “technical” musicians and instrument builders and designers, that good audio design shuns these simple methods, and using (particularly) CMOS in tone generation is for amateurs and hobbyists, and can never produce acceptable, let alone professional results – I was in that camp until quite recently.

[i]”------------

>> Are you aware that the SERIES 91 theremins are not heterodyne instruments at all? They are gestural CV tone generators.

--------------[/i]

Yes – And I think I remember at the time some people bemoaned Bob Moog’s departure from “True” Theremin technology. I think it was (as with the E-Pro) only Bob’s mastery of analogue crafting which made the 91’s desirable to Theremin ‘purists’ .. The ’91’s were analogue synthesizers with gestural control – But call a Theremin a Synthesizer, and a lot of Thereminists get quite upset!

[i]----------------

”>>I think that these are considerations that are of interest to engineers but are of little concern to musicians. Since instruments are bought mainly by musicians, the impact of technical specs on sales is probably negligible.”

---------------------[/i]

I have no way of knowing.. What I do know is that the adverse reaction I have had from some Thereminists (not you) when I mention doing anything digitally, made me aware that it might not be a good idea to go this way, or to disclose the truth if I did.. I had a lot of reaction right at the beginning, when I was looking at using a PSoC mixed signal processor.
What I do know is the effect this delusion has had on me, and on my design output – I was happy to use a limited amount of digital technology for control and ‘non audio’ processing, but avoided looking at using digital for signal generation – this bias stopped me from exploring possibly fruitful ways of quickly and cheaply getting product onto the market.. It was only the South-Bank Theremins where I (through having to get them built to an impossible deadline) used CMOS heterodyning (combined with separate ‘true’ Theremin analogue heterodyning) to provide a digital ‘oscillator’ and sub-oscillator.. This Theremin had waveshaping and mixing for all signal sources – and I found that by muting the analogue signals, I was still able to produce wonderful sounding tones.
I am sure there must be other developers who, through irrational prejudice and belief (rightly or wrongly) that using CMOS sound generators would impede acceptance of their products, have limited themselves, needlessly, to purely analogue solutions.

[i]------------

>> There were apparently some innovations involved with the Etherwave Standard when it first came out but Bob did not patent them because the patent process is slow, expensive, and he felt that the market probably wouldn't justify the cost. He went ahead and manufactured his Etherwave kits without the protection that a patent would have offered. Sure enough, within a very short time,

Gordon wrote: [i]"Personally I am rather pleased that I had an opportunity a week ago to play extensively with an Etherwave Pro, before knowing how it worked could taint my perception."[/i]

This statement encapsulates the issue - the bias is there, embedded - the realization by Gordon that [i]"knowing how it worked could taint my perception."[/i]

Gordon is hardly a Theremin purist! -- It is a MASSIVE effort for me to over-ride my instincts.. Even now, despite having played with CMOS generation of Theremin audio, and being extremely pleased with the results, I suspect that if a new Theremin was to appear, and I knew it had digital heterodyning, I would have a bias against it - or certainly evaluate it more critically.. Bias and predudice.. they dont vanish instantly even when one realises they were based on false ore irrational assumptions.



Gordon wrote: [i]"I imagine there are one or two people who, on reading Fred's posting, felt that it validated their preference for some other theremin."[/i]

I think this is likely to be true - but I must say that such a conclusion would be wrong.. Oh yes - the sounds may not be to their liking.. That is a matter of personal taste - but this 'liking' or 'disliking' will apply to every variant of Theremin (or, for that matter, any musical instrument).

Having a hard-nosed evaluation of the source signals (those from analogue or CMOS generators) it can be clearly seen that there is NOTHING which, after the filtering ( required to remove the 'sum' components, both in digital and analogue heterodyning) could identify or differentiate between them - Give me audio samples of both, and I would not be able to tell you which was produced by a CMOS XOR and which was produced from an analogue 4Q Modulator.

Yes - There are DYNAMIC differences in harmonics from an analogue heterodyning stage (harmonics produced by analogue source signals will influence the output harmonics from an analogue heterodyning stage, and as these input harmonics change due to oscillator synchronization etc, will produce a changing harmonic spectrum as the instrument is played - something which cannot happen with a digital implementation) but these will only ADD harmonics to the ANALOGUE version..

What I am saying is that there are no 'nasty' added harmonics produced by CMOS heterodyning - The waveshape is consistent - and without dynamic post-processing to deliberately vary the harmonic content, would be uninteresting. Gordons comment that the Epro "timbres are a little too refined for me" are exactly the kind of issue which one would expect from a Theremin based on digital heterodyning.. I think that good players impart harmonic variation through their playing style - particularly vibrato - as the CMOS heterodyning will create harmonic distortion from rapid dynamic frequency changes in the same way that analogue heterodyning does.. Something which a sample playback system (or at least standard sample playback as used in samplers) can never do.


I would like to thank Gordon for the comments he made to me - Gordon contacted me following this posting (#10) (http://www.thereminworld.com/forum.asp?cmd=p&T=4544&F=3) which stated that that the E-Pro was a sample player, to ask me if this was true.. I disclosed the truth to him.. In a following email to me, I was struck by his reaction - He showed me a whole positive angle on the matter which I had not embraced before.. I had been on the fence - half inclined towards my previous bias against the CMOS technology in the E-Pro.. And still feeling a bit that Bob had taken the p*** out of the Theremin community - And half accepting that what he had done was clever and extremely bold.. Gordon's email pushed me off that fence.

>>[i] Well Fred, I don't know what others would have said, but I would have responded with, "I don't care if Bob makes a theremin that produces its sound by sticking Lilliputians with hat pins. If I like it I'll buy it."[/i]

That pretty much sums it up for me. To quote Elvis from the movie 'Loving You", when asked about his opinion of a modern jazz record they were listening to at a party,
[i]"Frankly, I have no idea what the hell your talkin' about"[/i]

Andy

""Frankly, I have no idea what the hell your talkin' about"

LOL! - Do I know that feeling! - What with everyone blabbing about the football...

They get so passionate, so intense, so personal - It is so real to them -

"but hell - its only a game...." But thinking about how an XOR gate can affect my emotions, cause such tension, pose such ethical issues for me - I am forced to laugh out loud!

Perhaps everything is really just a game..

Funny creatures, us humans!

[i]Frankly, I have no idea what the hell your talkin' about[/i]

Don't worry about it! I only have a tenuous grasp on what I'm talking about. Certainly not solid enough to explain it coherently and simply.

But the managerial summary is -

It all comes down to the different ways that sounds can be represented within different sorts of electronic circuits, and what information is retained and what is thrown away in different representations, whether the information degrades or not during it's journey through the circuit and how easy or hard it is to process the information in different ways.

Dr Moog made a very unusual choice when he built the ePro and if you're interested in that sort of thing (*) then one's immediate reaction is most likely to be Aaaaaaaaaargh! Nooooooooooooo! followed by a lot of head scratching before the light bulb above your head clicks on and you realise just how clever it is.



(*) My opinion is that, just as a designer of theremins will benefit from a reasonable grasp of the musical needs of the player, so the player will benefit from understanding to some degree the workings of his instrument. Just as a Formula One racing driver is bound to be fairly well versed in the mysteries of the internal combustion engine, for example.

[i]Gordon's comment that the Epro "timbres are a little too refined for me" are exactly the kind of issue which one would expect from a Theremin based on digital heterodyning.. I think that good players impart harmonic variation through their playing style[/i]

Then I shall endeavour to become a good player in order to make the instrument sound better!

(Haha! I'm only teasing you, Fred. I know you didn't mean it like that.

But there is a lot of truth in the notion that the better the player, the better the instrument sounds. I remember as a kid when my uncle, who was the organist for Norwich cathedral, played my mother's Hammond organ. It sounded like a [i]completely[/i] different instrument in his hands.)