Moog Theremini!

"An overall latency more than 8-10 ms is enough to cause problems and at 12-15ms a theremin is utterly and completely unplayable." - kkissinger

Thanks for those concise figures, Kevin.

With modern processing, 5ms is a long time - there is no excuse for long latency due to the digital processing IMO..

But there is difficulty at the front-end, particularly if dealing with audio input - because a full 200Hz cycle takes 5ms, 100Hz takes 10ms. This becomes a limitation on simple pitch to voltage conversion, as in the EW+ and EWP.

With a theremin, this conversion latency problem can be easily overcome (although I seem to be the only person to have ever done it) by multiplying both reference and pitch oscillators, and heterodyning these multiplied frequencies to provide an "audio" signal 4 octaves higher which can be converted, a 16Hz signal (with direct conversion latency of 62.5ms) becomes a 256Hz signal (with 3,9ms latency).

What I wonder is whether the latency demands are the same in the bass registers (say below 200Hz) as they are for the higher registers - I have thought at times that perhaps latency "requirements" could be related to pitch - as in, 5ms (1/2 cycle of 100Hz) may be ok for 100Hz, and 31ms latency may be ok for 16Hz.

Not that any of the above has any real relevance - just pure curiosity .. But if the latency in the theremini is due to front-end filters (hardware or software) that must cater for the lowest difference frequency the processor must measure, then this may be cobbling other stuff that could update much faster.

I actually find it hard to imagine that the problem is actually in the digital processing of the waveform / sound engine - there's not a hell of a lot that needs to be done there as far as I can see, certainly not enough to consume all the cycles of a fast DSP!

I strongly suspect that the problem is at the sensing side - the filters and averaging and perhaps too-low difference frequency - problems that anyone who understands theremins at all would have avoided.

Fred.

@Dewster: "

OK, one more audio file:http://www.mediafire.com/listen/0d36y9lrtm3zhat/Theremini_touch_response_2014-09-23.mp3"

OMG! - That just says it all!

Particularly if you remember that this latency isn't just between extremes - its there between any intervals regardless of how close or far apart these are!

"The problem is due to 'overshoot'."  - kkissinger

Which can easily lead to operator induced oscillation.  As a flight simmer of yore on a 12MHz 286 AT I have deep knowledge of this.  ;-)

"The problem is due to 'overshoot'."  - kkissinger

"Which can easily lead to operator induced oscillation.  As a flight simmer of yore on a 12MHz 286 AT I have deep knowledge of this.  ;-)" - dewster

Exactly!  The same principle.

Thanks Dewster for that last sound file! That did say it all! The tests I was going to do when I finally got time with the device were basically along the lines of what you created in the last example.

Kevin, you are right on the money, well said!   

If there was ever one thing that defines what a theremin is, it should be the instantaneous nature of the capacitive interface.  There must not be any delay between the player's movements and the sound that is reflected back in the audio monitor. No other standalone musical instrument has latency introduced (beyond what happens w the speed of sound as Dewster described). The absolutely critical feedback loop between the player movement, and their pitch and dynamic response is totally obliterated once latency is introduced.  I echo what Kevin said. There is no solution or 'cover up' that will fix this after it has been introduced.

IMO This needs to be reiterated by as many people as possible who are actually theremin players.   Latency out of the box is unacceptable!  It is impossible to properly learn how to play the instrument if there is any latency. It's hard enough to learn with the multitude of other variables already presented to a student learning the instrument.

Then there is this side of things that is still bugging me....  playing an instrument versus playing 'with' a toy.  Anyone can play 'with' a toy. It takes no skill or discipline whatsoever. This confusion is clearly being perpetuated by Moog Music...  by marketing a toy as a proper musical instrument.

A company that sells Toy Pianos does not attempt to convince anyone that they are selling real pianos.  Why does Moog Music think it can get away with marketing a toy Theremini as a real theremin?   This is actually easy to answer...  It is because the people building the device, as well as the people who do the marketing for the company don't actually have any idea of what defines a good theremin...  To know this would require interfacing with theremin musicians that are knowledgable about the instrument TODAY, RIGHT NOW. This is not happening, or at least it is not happening now as far as I am aware.

Moog Music Inc. did actually do this sort of thing not so long ago. The last time it happened was at a panel discussion that I was a part of at the EtherMusic Theremin Festival in 2008, that Moog Music sponsored. The goal of the panel discussion was to talk about what thereminists wanted in the next generation professional theremin from Moog.  The data and record from that event must have gone missing. 6 years have passed and there has been nothing new or revolutionary in the way of theremins.  50 years of Bob Moog's experience building theremins seems to have been casually discarded to make way for the great new frontier of toy manufacturing. 

Four months after the release of this 'new' theremini, the evidence has been presented by us "outsiders". People who are knowledgable about theremin engineering and theremin playing have said what each felt they needed to say.  Is there anything more that needs to be said about this device?  Is it worth anyone's time and energy anymore to continue the discussion on this subject?   Up until recently I thought it might still be worth my time, but the issue of latency, is as Kevin said,  a show stopper.

" Is it worth anyone's time and energy anymore to continue the discussion on this subject?   Up until recently I thought it might still be worth my time, but the issue of latency, is as Kevin said,  a show stopper." - Randy

There is one reason, and one reason only, that I can see for continuing this "discussion!.. Its this:

If the discussion doesn't continue, if this thread drops off the bottom into obscurity, then the only prominent voice of sanity on this matter on the whole WWW will drop off the radar.

There are people who may be seriously interested in buying a theremin, and do some genuine research with the thought in mind that the theremini looked like a good buy..

If they visit TW in this search, and see no thread about the theremini, but see the M-ugh advert flashing at the top of the page, they are more likely to fall for the M-ugh scam than if they found this thread and read the truth.

This is the only reason and justification that I can see - But we dont actually need to post any new comments - its quite easy to pop a thread back to the top.. As some folks here have discovered.

Fred.

The Theremin community has been quite lucky in the past to have been supported and supplied by wild-eyed EE fanatics like Theremin and (Bob) Moog.  But companies go out of their way to not hire monomaniacs (at least at the technical level) so it's probably unreasonable to expect the next big thing (or even maintenance of things they themselves developed and sold in the past) from that direction.

The reason no Thereminists were consulted during the development of the Theremini IMO is secrecy for it's own sake, and the need to "spring" new products on us at NAMM, which they likely feel best catapults the propaganda and hype.

It's all so tiresome and predictable.

... Is this theremin completely manufactured and assembled in the USA, or part(s) of it are made overseas?

Not that it matters much...

The sticker on the bottom says "ASSEMBLED BY HAND IN ASHEVILLE, NC". 

Most of the parts are probably manufactured overseas.

"The sticker on the bottom says "ASSEMBLED BY HAND IN ASHEVILLE, NC"" - Dewster

Ah, but there's a way to make a statement like that true, but perhaps not what one thinks by reading it.. Buy in ready built and tested boards from China, buy in molded plastic cases from China, and in Asville get someone to put the boards into the cases, by hand!

I would be interested in seeing the following statement:

"Designed, Developed, prototyped and tested by Moog engineers in Ashville prior to being put into production.."

Because I am actually coming to think that perhaps some management / marketing  bean counter never involved Moog engineers at all, and simply palmed the whole project off to the cheapest Chinese design house he/she could find.

Fred.

Just googled "theremini"

The 2nd entry in the returned list was http://www.thereminworld.com/moog-music-theremini-theremin which is an advert for this toy and only has a link to Randy's original, mostly complimentary review.

Perhaps, some warning should be placed somewhere prominent, so that people dont get misled by this Moog advert on TW ?

Or perhaps a few more links at the bottom of that "article" (advert) - links to where Randy and Peter and Kevin and Thomas all clearly state that the "instrument" is not usable as a theremin..

Dewster wrote: "It's all so tiresome and predictable."

Oh, come on Doos!!

That sounds very jaded and cynical. Fact is, YOU LOVE IT! We all do. This whole Theremini debacle has inspired more posts than the invention of the telephone. ☺