"Tanks" For Nothing!

Posted: 8/29/2013 11:01:40 AM

From: Canada

Joined: 8/1/2008

Thierry wrote: "......seen dewsters latest statements he appears to me rather not interested in what I told and thus I'll stop wasting my time by sharing my knowledge and experience with him."


What you must remember when you write something to a public forum like TW is that you are not just talking to the individual you are addressing - you are talking to everybody, and possibly even to posterity. Dewster Schmewster! This is the INTERNET where everybody is an expert (including those who haven't the slightest idea what the fuck they're talking about).

Thierry, I loved the way you characterized me (above) but I think maybe you made me just a bit too polite. LOL



Posted: 8/29/2013 12:09:16 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

Oh lord!

This is the trouble (for me) with TW.. I want to read it but take a break from "contributing" - just dont have the time or motivation right now...

But reading without commenting is proving too difficult - it doesnt matter how 'benign' a thread appears, or how "balanced" one thinks one is when answering - people (myself included) seem to be extremely touchy and passionate about their 'corner' of the "theremin world"

So my parting comments are these:

1.) A common "mistake" (one I often make) is to regard what one is saying as a waste of time because you feel that the person you are responding to isnt getting it (for whatever reason) and/or is being antagonistic.. the "and thus I'll stop wasting my time by sharing my knowledge and experience with him" is IMO an example of this...

Stop sharing with "him" and you stop sharing with everyone! - and this would be tragic IMO.. I get loads of useful and often different insights from Thierry and Dewster and others.. I may not "agree" with many of these, but I would miss them if they ever dissapeared.. And I would particularly miss these comments from good rational engineers or musicians - and if I was to rate the engineering capability at TW, Thierry and Dewster would be up at the top..

So please, the two of you.. Dont stop sharing your ideas! ... There are many people reading everything you post, and the MAJORITY of these people are, and will remain, invisible.


2.) All of us believe we know what we are talking about - and we do! But all of us could be wrong about some fundamental matter/s .. oh, its unlikely IMO that some established "facts" are wrong, but they could be!

IMO, it is unlikely that Lev (and all following theremin designers) missed some simple linearization scheme, or that the series resonant antenna equalization scheme is a delusion and/or serves little purpose, but I am nonetheless extremely interested when a challenge is made to established ideas.. Particularly when these challenges are based on scientific observation or theory.

3.) I do not think that there is only one route to theremin development - Lev never had any theremins to examine before he developed the instruments whose qualities we are all trying to attain! - Likewise, AFAIK Bob Moog never played with many (if any) theremins before he started building them..

So, for me, there is no "absolute" here - IMO, an extremely good understanding of music /physics / maths / electronics etc is enough to enable a designer to produce a good theremin.. Likewise I think that examining existing theremins is a good route, particularly if the engineer has enough of the skills and knowledge (music/maths/physics/electronics)..

So the best would probably be the combined "technician" and "scientist".. But whatever.. Its just sad to me that we seem to be competing rather than cooperating.. bloody human nature I suppose - find some "quality" - be this what it may, even faked "spiritual guidance" by which we can elevate our status.. and find something in our "competitor" which we can hint at as being a "flaw"..

Or - As I think is often the case - interpret some careless words from someone, and percieve these as an attack or insult, when there was never any such intention.

Before I go, just want to say thanks to everyone at TW for all the rich information and discussion, and in many cases real friendship.

Thanks for something!  ;-)


Posted: 8/29/2013 12:50:31 PM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

Randy said: "the volume antenna doesn't offer enough dynamic range while still allowing a quick enough response"

I think your everywhere location at one time was just over an hour from my living off the edge of the Pechanga Reservation.

What many people misunderstand is the theremin by nature is perfect.

It can have a perfectly linear pitch field, naturally, a voice that would get Clara Rockmore's attention and be drift free. In other words on the same musical note when turned on in the morning. Most improvements are to correct errors humans have added to the natural design.

I am not designing a musical instrument, rather exploring the fullness of theremin. I have discovered many things of what the theremin wants to express and maybe one day share with you. Volume response was one of the fascinating areas that has been held back in development.

The theremin reminds me of the three great religions that have the same early bible and see things so differently, everybody is an expert.

It has been ten years and I still have not built a finished theremin, it has been more fun to explore.


Posted: 8/29/2013 5:02:27 PM
randy george

From: Los Angeles, California

Joined: 2/5/2006

I may change my location to something more specific soon.  I used to live in LA, and I will be headed back there again, but I don't have a time frame yet.

When I wrote in the 'self quote' about non-linearity, it was in a broad sense to hopefully fit the comic intent of Thierry's explanation.  at this time I feel like I understand linearity from a player's point of view. the theremin's circuit design itself is not wholly responsible for linearity, but poor choices in the instruments chassis design can greatly affect linearity, as can poor choices in the players technique, stance, and instrument height/position...   if I didn't understand it as well as I do,  I would not have been able to make adjustments to my setup that offered repeatable accurate measurable results proving that I am achieving a mostly linear playing experience.   To just say, "oh, that feels linear" is not acceptable to me.

I am currently communicating with an engineer from Seattle who has devised a method for the player to custom calibrate linearity of the pitch field. That, I feel, is a step in a good direction, but I can not be guaranteed that it will work, because I must verify that it works for me, by my own methods.   I don't understand even a quarter of what has been discussed in this thread ( i do my best to follow), but I do know one thing.  it takes two people minimum to make a great theremin... one theremin engineer, one proficient theremin player. (but what defines proficiency? there's actually no such thing in the realm of theremin playing, everyone is a master of his/her own way.)

I do not believe that Clara was a highly developed master of her instrument within the first couple years playing the instrument.  it was a process, and she developed herself, along side of the theremin design being refined and improved.  The rest of us players are doing the same thing. and all the engineers out there are very likely going through the many processes that Leon Theremin must've had to endure.  (not with regard to specifics, but scientific method).

I'll check out your work Christopher... (but as I've alluded to in my last post, it would be much better to meet in person.)

Posted: 8/29/2013 8:40:59 PM

From: Colmar, France

Joined: 12/31/2007

I, personally, see linearity under 2 aspects:

a) it is highly subjective - every player has a different technique and stance, both influence the field geometry in a way that we will most probably never be able to talk about absolute linearity.

b) it is often overrated, especially by non-musicians. Every violin/viola/cello/double bass/guitar player is used to some shrinking of the tone spacing for the higher tones. Nobody has ever made an attempt in 300 years to build a linear violin! Thus why should a similar phenomenon on the theremin not be acceptable as long as the tone spacing remains practicable and is not shortened in a way that a slight vibrato will move over three halftones?

Posted: 8/29/2013 10:17:08 PM

From: Northern NJ, USA

Joined: 2/17/2012

Head down, doing my due diligence re. the possible linearizing potential of the parallel tank + EQ coil.  On my (hopefully last) pass of the Excel sim which I will likely use as evidence / an intellectual crutch.  Spent hours today admittedly sloppily and randomly tweaking my EWS and, while it is more linear than I remember and I can get it seemingly fairly linear up to an inch or two of the antenna, there is frustratingly no clearly obvious "best" tuning jumping out at me, and the sensitivity for the more linear settings seems a bit high (open / closed fist = ~1 octave).

IMO, the major reason to address linearity via post-processing is to simultaneously address variable note spacing (AKA sensitivity) which to me is probably a bigger playability issue.

Posted: 8/30/2013 1:03:34 AM
randy george

From: Los Angeles, California

Joined: 2/5/2006

I think there is one very significant reason why a theremin greatly benefits from a linear playing interaction: to make the instrument easier to play.  And I mean universally easier... this means a person with a moderate facility to play the instrument will have a better experience, and the person who wishes to play with virtuosity on the theremin can also reach higher levels of virtuosity.  Everyone will come to agreement when regarding the theremin as one of the most difficult instruments to play well in the entire world of music.  If so, then it makes little sense to me, why all ideas for improving the playing experience should not be explored or that they should be abandoned because other highly evolved instruments have a non-linear interfaces that works fine.

Specifically for the theremin from a technical performance point of view, a consistently linear pitch interaction affords a player a great advantage... which is to repurpose memorized motions from one part of the playing range to another part of the range. the end goal is to increase efficiency, reduce the margin of pitch error, and allow a player to focus more on being expressive/musical rather than fighting the interface. However (a big however) this advantage really only applies to theremin players who require precision to a certain degree.  

Contrasted with precision playing... To play the theremin with wide interval spacings, relying mostly on arm/body muscle memory rather than hand/finger muscle memory, there would be much less of a need for linearity.  the same applies for the theremin playing style of constant wide (arm motion) vibrato, and heavy use of portamento between notes. the reason linearity is not necessary in these circumstances is because the greater margin of error that is permissible (in arm hand finger movements) because errors are much more easily masked.

as with all things, it's both important and necessary for one group of people and completely useless for another group.  But in this post, I'd like to focus on why it is important.


for anyone that is unaware, I have been a bassoonist in the past. i played bassoon for ten years and developed to the point where I could call myself proficient. there are many different companies around the world that make good german system bassoons... number one I'd say is German make, Heckel. number two I'd say would be Fox from Indiana, USA.

I personally regard the bassoon as another one of the most difficult instruments to play well in the world of music.  I know, from experience, the difference between a poorly made(or average) bassoon and well crafted bassoon.... and what is the biggest difference? The better bassoon is easier to play.  The bassoon as an instrument is very old... many people know that. but what many people do not realize is how complex the modern day German system bassoon is. I will just say for brevity, that it is mind bogglingly complex. The French system bassoon is also complex.

getting to the point: if bassoon manufacturers a hundred years ago decided that it was not worth it to improve the design of the bassoon, simply because of technical shortcomings or disagreements with the old systems,  then there would be no possibility for virtuosity in modern day bassoon playing because the instrument would be simply be impossible to play without squawking and cracking every other note. 

right now, IMO, there seems to be a very low number of people playing with the kind of precision that Clara could play with.  being a trained musician definitely helps, but the biggest obstacle IMO is the lack of linear playing interaction. From my observations of her playing and my understanding of my own playing as well as others, I think Clara actually did have a very linear playing interaction with her instrument. No one can prove this today because as each person possesses capacitance changing functions unique to his/her body size, playing technique, etc. even if someone got behind her instrument, he/she would not be able to replicate the interaction that Clara had on the same instrument.

The second biggest obstacle (which is really another topic) is the level of awareness a theremin player has with regard to intonation. it's somewhat relevant here in this topic, because I feel it's really the end goal with making a theremin instrument easier to play. to play the instrument in tune without too much deviation from the intended key or without too much inconsistency with interval width/finger/hand spacings... to play without too much over shooting/undershooting of the pitch jumps, and with as little error masking and correction as possible.

i guess, I would like to just say to the engineers out there, please do not give up on linearity, but be aware that the instrument is only part of a larger equation to obtain a linear playing interaction. It may be a very small crowd of people that is reading these posts, but one day hopefully maybe it will be a bigger crowd of people. and I think everyone's point of view is invaluable when shared... that's IMO how progress is made.


Another topic for later, I just wanted to throw out. I have a great experiment that I would like to try one day when I get enough hobby cash. I would like to put the Etherwave Standard into a variety of custom built housings... then take measurements of the effect the chassis/housing has on linearity. at this time, I am convinced that the EPro and Henk theremins produce the most linear interaction because of their housing.... specifically because of the suspended/isolated pitch antenna.   if anyone is interested, and if you have the time and patience, you could perhaps test your theremins sans housing, and observe/report the results. I only have my ePro for now and I'm happy with the way that it plays so I'm not opening it up again. I sold my original EW some time ago, otherwise I'd try this now.

edit: sorry for going off topic on this thread. :P  back to you guys.

Posted: 8/30/2013 1:37:28 AM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

Excellent observations Randy, you understand the possibilities of what the instrument is intended to be. I pulled my EWS out of the closet a couple of weeks ago and made another startling discovery. It is part of believing there will be a renewal of theremin interest in the near future. I hope all these modern day theremin designers have their product ready, so the new young Thereminist will be around a while. A hand full of people are aware of what will bring about this renewal. It is based upon us old timers and one who is really crotchety, sharing knowledge that once we were young and it is still fun to remember what it meant to smile.


Posted: 8/30/2013 4:17:55 PM

From: Northern NJ, USA

Joined: 2/17/2012

The point of this thread was to draw more attention to the linearizing network at the expense of what we normally think of as the tank (and to drive Thierry crazy ;-).

There are of course many ways to organize one's thoughts when thinking about the behavior of various circuit topologies (and perhaps I've spent way too long in series tank land) but conceptually I tend to see all Theremins as based on a variation of the "real" EQ coil / antenna capacitance series tank.  For instance, to me the EWS has an odd behavior modifying parallel LC "network" hanging off of the "real" tank.  One could remove this "network" (other non-resonant circuitry modifications would also likely be necessary) and still have a decent working Theremin, but removal of the "real" tank would severely hobble it.

Posted: 8/30/2013 10:43:32 PM

From: Northern NJ, USA

Joined: 2/17/2012

Working on the Excel sim some more.  At first I didn't think the parallel tank was right, but after comparing it to LTspice it seems OK.  Phase detection is very clear for the serial tank, but for the parallel tank it's a nightmare. 

I know!  Let's play "find the resonance points in the pizza"!

For many parallel tank tunings there are two valid tank resonance points, as the two green arrows in the upper graph show.  The green arrows in the lower phase graph shows falling zero crossings for both.  This is likely not the most optimal tuning for the EWS but I believe I've tuned mine on the bench for the above scenario.  If I bring my hand near the antenna the tank oscillation "snaps" to ~270 kHz, pulling it away it "snaps" back to ~260 kHz.

The fainter traces are the simulated result of the application of a small "Cdelta" capacitance to the antenna.  The purple arrows show a reduction in antenna voltage with increased capacitance, something I see in my EWS on the bench.

Anyway, I can't quantitatively check simulation linearity without proper resonance detection, and the above is something of a can of worms.

Here is what the simulated linearity of a simple tankless LC Theremin looks like:

The lower graph shows reasonably constant sensitivity between 0.2 and 0.8 meters, which covers about 5 octaves with the given note spacing.  The far field is easily corrected with body capacitance, so the trick is to linearize the field closest to the antenna.  The "Nonlinearity" number is a ratio of the sensitivity of the point nearest to the antenna to the point of lowest sensitivity out in the mid field.  I was going to use this to see how various adjustments of a given parallel tank would score, but I'm stymied by the multiple resonance and phase detection issue described above.

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