Preference: Does anyone actually even want "perfect" linearity?

Posted: 1/8/2013 5:18:28 PM

From: Brooklyn,NY

Joined: 12/1/2009

Just curious.    I've been tweaking the new theremin Ive built (posted an image awhile back)  and was really pleased with myself when I achieved pretty-much-damn-near-perfect linearity,   tunable up to 7+ octaves, right up to the antenna- within <2mm-.     'Wow!',  I thought smugly.


Yesterday i dropped the instrument off w/ local musician who has agreed to be my guinea pig.  This guy is no slouch- he is a well regarded member of the theremin community, a pro,   and a musical master.  Unfortunately,  he wasnt as stoked about the linear playing field as I had fact he even asked if it would be possible to switch it back or even have it be 'switchable' by the player.

His thoughts were that he was just used to the playing field of his other instruments - ew's, and melodia.   Im sure that is true but Im also I'm thinking that perhaps 'perfect' linearity is maybe not so great, at least for human arms and fingers. There does seem to be an inherent( though possibly coincidental) logic with other instruments(violin, guitar) - how the collapsing of space between notes seems to correlate with the flexibility of the players hand in that position... right?  

  Most theremins seems to have an un-linear pitch response(to varying degrees, at least), including the RCA.   In everything else, I just assume that the unlinear field is "just the best they could get"- however, everything in the RCA was designed and laid out by Lev.  I refuse to believe that he left  his instrument with a unlinear field simply because he couldnt get it any better.        I propose that  the 'perfect' linearity for pitch, is in fact slightly (and evenly) compressed as the scale goes up- to feel more natural for the musician. 


Posted: 1/8/2013 6:02:26 PM

From: In between the Pitch and Volume hand ~ New England

Joined: 12/17/2010

I would not want a perfectly linear theremin. My Wavefront is a classic example of that and I love it. My Subscope has a different linearity as well, and it is almost perfect, but not quite. I think for player comfort, it is ok (at least for me) that the notes are closely cohabiting in the upper range because i have small hands and when I extend my arm to play, i don't want to do more work to reach the notes i intend to.

I think maybe Rob (i assume that it is him you are referring to, just a "wild" guess) might try your setup for a while and see if he can get a feel for it? Maybe it is so different than his "normal" set-up that is it totally foreign territory on first encounter. My 2 theremins are so different from each other, but with time and understanding, my playing adjusts quite easily from one to another...

Posted: 1/8/2013 6:37:25 PM

From: A Coruña, Spain

Joined: 9/26/2010

I personally would like perfect linearity. It's quite a nuisance to play some melody, then play the very same melody one octave higher, and not be able to do it with the same movements but have to adapt instead. It would be easier with perfect linearity.

Of course, it's just a nuisance that one gets used to, it's by no means a tragedy. And it's understandable that when you get used to a nonlinear theremin, playing on a perfectly linear one may be harder. But I don't see how it could be harder in the long run. Do a particular hand movement to play a fourth, move your arm a bit do the very same hand movement to play a higher-pitched fourth - much easier.

Posted: 1/8/2013 6:47:37 PM

From: In between the Pitch and Volume hand ~ New England

Joined: 12/17/2010

Personally, I like the challenges of getting to "know" your instrument(s) and adapt to its playability. To me it feels like getting a rescue puppy and play with it in order to bond and trust each other. I donno why I like challenges, it makes it for a more versatile player and keep your mind flexible and on the edge. Love it.

Posted: 1/8/2013 7:01:39 PM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

When you start out with perfect pitch field linearity, it is much easier to adjust it to a likeable  non linear response, than vice versa. Similarly starting with a smooth theremin sound it is easier to add in buzz than remove it. A theremin voice should begin with more harmonics that can be tuned out as it is more difficult to add to the voice once it leaves the theremin. Personal preference is by far what I consider most important even in the physical design. I think for the new generation of theremin students perfect linearity is more instinctive as "every" octave being of equal width can be held in your hand.


Posted: 1/8/2013 7:55:49 PM

From: Kansas City, Mo.

Joined: 8/23/2005

I prefer a pitch response that is a linear as possible.  I've tweaked my Epro to achieve 5 1/2 playable (i.e., generally linear) octaves.

I want consistant control over the pitch and vibrato depth across the range and overly-close note-spacing does not work well for me.

Posted: 1/8/2013 9:51:46 PM

From: Colmar, France

Joined: 12/31/2007

The "problem" is that each player perceives linearity in a different way. Thus there is no absolute linearity but only "felt" linearity by the individual player, because it depends on many factors, I will just cite two of them as examples.

- Fingering technique: Using Carolina Eyck's technique with extremely stretched fingers you will feel higher tones much wider spaced as if you move from one tone to another with a rather closed fist and only few finger or knuckle extension, because the fully stretched fingers will make the pitch antenna see much less capacitance as a full hand at the same distance.

- Body posture and movement: People who tend to stand far away from the theremin and play the high register with a stretched arm will feel tones closer than someone standing nearer and immersing more of the arm in the pitch field. Those who move their body closer to the pitch antenna will feel higher tones still wider spaced.

When I was for example asked to tune Carolina Eyck's and Thorwald Jørgensen's theremins for optimal linearity, I had them playing almost the whole time so that I could observe their movements and they could tell me what was not yet perfect. This allowed me to do the needed modifications until they were satisfied. But when I tried both instruments they appeared less linear to me because my playing technique, posture and body mass was different.

Finally this experience is one of the reasons (among others) why I changed my opinion. I'm now convinced that top level theremins can never be built in mass production but will have to be individually manufactured for and with the individual player. There are things which can not be set just by turning a knob.


Posted: 1/9/2013 3:13:15 AM
randy george

From: Los Angeles, California

Joined: 2/5/2006

I think a perfect linear pitch interaction is essential, if a thereminist aims to develop his or her muscle memory beyond the point where it can exceed the necessity to rely so much on aural skills to accurately place notes. A linear playing interaction is not important if a theremin player is already happy with his or her accuracy, note transition time, margin of error and correction time or error masking time.  I have spent the better part of the past six years focusing on this core element of my instrument's interaction, because I have learned the best way to achieve what I wanted musically was to have a firm foundation of what supports my musical voice... my interaction with the invisible interface.

I say perfect linear pitch "interaction", because, as Thierry has mentioned above, Pitch Linearity (what is perceived as a 1 to 1 ratio between changes in capacitance and changes in chromatic note output) is a product of a number of variables.  These variables include, of course, the theremin circuit itself (which can be tweaked and modified), but there are many additional factors that are not easily modifiable, because they are difficult to see and or measure. also because of these additional variables, a perfect linear interaction can never be achieved with good circuit design alone.

Many theremin players may feel they have a linear playing interaction, but they may actually have only achieved a comfortable balance between their memorized movements and permissible margin of error according to their perception of intonation and playing style.

A pitch interaction can definitely be made "more" linear by the circuitry of the theremin itself, but it's also important for the player to become aware of all the variables that affect the interaction externally. it's even more important to understand that there is ultimately only one variable that changes. That is the averaged capacity displacement of the space around the external point on the theremin at which the pitch antenna begins.

The additional variables include the size, shape, mass, density of the instrument cabinet, the mass of a player's arm, position/posture of the body, proximity of nearby objects, and the player's technique that used to displace capacity.  

Linear pitch interaction can properly be measured by using a momentary fixed change in capacity (made only by the player of the theremin) across various locations in space along the 3-5 octave range of the theremin. the most consistent method is by using the change in capacity of a closed fist to fully extended fingers.  If the closed to open gesture creates the same interval, regardless of the position of the arm's location within the playing range, then the interaction can be considered linear.  To what degree the interaction is perceived to be linear depends on the aural acuity of the person who perceives the sound.... unless a method of quantitative analysis is employed. 

last year, I published a software application that can suit this very need. It graphically reflects pitch in a high resolution visual tuner that tracks incoming audio signal at an extremely fast rate. This allows for the intonation to be reflected back to a player in real-time with high precision. most tuners, digital or analog, have a non-real-time response, making it difficult for us to draw a synapse in the brain to effectively connect movement with sound.

I use an octave as the pitch interval (from closed fist to open hand) to measure the linearity, but any interval size can be used as long as the motion is consistently yielding the same change in capacity. This means, that if a player is creating changes in capacity that include the arm or body movement, it is much more difficult to create a consistent test movement.

The change in capacity of a theremin from an electronic point of view is very *easy* to measure because the theremin circuit only interprets a singular value, where as from the point of view of the player, in 3D space the variables that can influence the change in capacity across the full playing range include a wide variety of objects, shapes, masses, densities that all must be averaged together... this collection of external influences is much more difficult to measure.

The ultimate gain from having a linear pitch interaction is to create stability in theremin playing. We, most of us who play the theremin, all want one thing... and that is for the instrument to be as predicable as possible so we do not waste the energy that is invested in interpreting a piece of music or executing an improvised composition with exactly what was in mind (or the composer's mind). When the interaction is linear, it allows for memorized motions, whether they be complex or simple, (using the hand, wrist, fingers, or whole arm) to be easily repeatable with a low order of discrepancy at any point within the theremin's multi-octave range.

With all of the above said, I must admit that the pursuit of a perfectly linear interaction is an extremely difficult voyage that has mostly to do with a player's own awareness of his/herself... However the process of investing energy, attention, and awareness to this area will eventually reward anyone, who decides to jump down the rabbit hole.  I say so, because with my Etherwave Pro, I have adjusted the instrument, and my playing posture, position, and technique to yield an extremely linear (measurable) 5 octaves. 

The goal in the end is to be happy with your playing, so that you enjoy what you do, right?  The nuts and bolts aren't always so important, unless you have a very specific need that must be met. for me, I think I've gone as far as I could possibly go to get what I wanted...   In a few weeks I'll have a video camera again, and i can perhaps demonstrate what I've described.

sorry if that was a bit full-on for anyone. Info vom.   Thanks Chobbs for starting this topic.

Posted: 1/9/2013 4:42:04 AM

From: Northern NJ, USA

Joined: 2/17/2012

I agree, nice topic.  Chobbs, what did you do exactly to get the 7+ octaves of linearity?

My feeling is that those who have played for a long time and adapted to various idiosyncrasies to the point where they actually prefer them are a rather tiny yet influential group.  Those who are beginners or intermediate players would most likely benefit from and welcome more linear behavior.  In any case, separate sensitivity adjustments for the near and far field (with middle field sensitivity set by the beat null position) might please almost everyone, particularly if implemented in a stable and simple to adjust manner.  This to me is one of the Holy Grails of Theremin research.

Posted: 1/9/2013 12:59:50 PM

From: Scotland

Joined: 9/27/2012

Initially when I was first new to my theremin I was hung up on the fact that non-linearity existed in the arm’s length distance between me and the pitch antenna.
Now, after a while of playing, I find that I am able to compensate (as much as a novice can) for that anomaly and have no doubt that the more I play and become familiar with the instrument, the non-linearity will be less of a problem.

I’m minded to the fiddle and guitar world here, more specifically the fiddle world: the non-linearity in a fiddle is obvious in so far as the notes bunch up the closer to the bridge they are played, although this non-linearity is consistent.

Although this non-linearity exists in every fiddle, fiddle players (or at least those who play classical music) are a pretty conservative bunch (with a small 'c' ) and if a fiddle’s neck length deviates from ‘standard’ by even a few mm, they usually wouldn’t touch the instrument with a barge pole. Having said that, every fiddle has a slightly different setup which the player does learn to accommodate in their playing of the instrument, and here, I would liken each theremin’s slight difference in non-linearity with the setup of a fiddle.

N.B. I can’t really imagine playing a fiddle whose note spacing was linear!



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