Shrilling - uneven tone in upper resgister

Posted: 4/7/2011 9:27:12 AM

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

Joined: 12/17/2010

On my Wavefront, there are 2 tuning knobs. the one on the left "should" stay at 12 o'clock and the other one on the right is a "fine" tuning knob. I use the fine tuning knob to the pitch range that I am needing for a song that I am playing.

Right now, I am working on "Pie Jesu". and when I come to the highest note, when my hand approach the antenna, it has a "shrilling" sound. And if I try to do a vibrato, it has a weird tone, as in thin, unsteady. It is hard to describe... I am sure one of you has experienced something like this...

I am wondering if I am not "high" enough compared to the theremin's height, or that is not really a problem. I guess I might need to get myself a platform or longer legs!

I might need a course on how to tune a Theremin!

I just received this from Gene Segal, all tuned up and in pristine condition. He switched the theremin for my left handed playing...
I do love my Wavefront, it has such a beautiful tone!!!
Posted: 4/7/2011 5:40:36 PM

From: Colmar, France

Joined: 12/31/2007

I'm not sure that this is a tuning problem. It may rather be an interference. Make sure that your cell phone, your wireless home phone and its base are at least 20ft away and try again.
Posted: 4/7/2011 11:11:35 PM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

Beyond any technical issues, in my opinion, there is a point on the high end of just about any theremin where it starts to sound shrill.

Granted, I have not had the pleasure of playing every theremin ever made, but I've played several, and I've found that to be the trend.

One option is to step down the key until the highest note in the piece does not pass the "shrill point".

Another thing to consider, assuming it cannot be tempered by the theremins onboard tone controls, is the amp/speaker combination used. They can have a significant impact on tone by adding "color" and harmonics.

Keyboard amps (and PA speakers) usually have a horn in addition to the cone speaker. This gives them an extended frequency response. If they have a treble control, try turning it down some.

A guitar amp, while not ideal electrically, generally has greater roll-off on the high frequencies and may tend to sound a bit less shrill overall.

Direct recording is a bit more problematic. Filtering can be applied in the recording/editing software, but the theremin sound on the high end is relatively pure and there's little harmonics to filter out.
Posted: 4/8/2011 6:52:13 AM

From: Canada

Joined: 8/1/2008

It doesn't sound to me like Amy is describing a simple timbre problem. She did not say that the sound was "shrill". She said it was "shrilling" which seems to indicate some sort of interference either coming from outside (as Thierry suggested) or being generated by the theremin itself.
Posted: 4/8/2011 9:34:10 AM

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

Joined: 12/17/2010

Hello kind thereminsits!

Well, I guess my set-up needs some improvements. I moved my Wavefront to the middle of my room and it sounded much much better. I had it near my computer for easier access to reach the controls for the background music and perhaps that was a factor...

Another factor I hink is I might be too short in comparison to the theremin's height. I might need to find a platform or wear platform shoes lol. I am still unsure of the position I should assume when I play this Theremin... I guess it's all about experimenting right?
Posted: 4/8/2011 6:23:32 PM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

Well. I did say, "Beyond any technical issues..."

And Amethyste did say, "It is hard to describe... " And she's right. It is often difficult to get an accurate sense of an issue from a simple description.

While Amethyste may have an issue playing because of a height issue, I don't think it could be affecting the timbre adversely, could it?

Amethyste - When standing next to the volume loop, where is it in relation to your elbow? Are you comfortable when you play, or do you need to hold your elbow out to get enough height?
Posted: 4/8/2011 7:42:37 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 . ...................................

Joined: 12/7/2007

[i]"Beyond any technical isses..." Jeff [/i]

;-) LOL!

I find this discussion, and particularly Jeff's opinion that theremins sound 'shrill' (as opposed to "shrilling")at higher frequencies quite interesting - and yes - "technical".

I do wonder if this [i]might[/i] have something to do with the relationship of pitch and volume oscillator frequencies.. In my experiments (circuit board level) I have noticed that when both hands are close to thier respective antennas (volume hand not so close that the theremin is muted - probably most noticable at mid - low volume position) any interaction between these oscillators becomes most noticable, and can produce low-level harmonics which are non-musical and unpleasant, but which are not percieved as 'seperate' 'ghost' tones - they simply make the sound 'shrill'.

The major mechanism is, I believe, the relationship between the pitch reference oscillator and the volume variable oscillator.. As volume is reduced, the volume oscillator frequency drops, and if it drops sufficiently so that sonic / ultrasonic beat frequencies are produced, these resultant frequencies can: A) be mixed with the audio output B) Mix with the high frequency audio produced from the difference (beat) of the variable pitch and reference oscillators [the audio you want to hear] and give unpleasant overtones.

Something like this:

Pitch Reference and volume variable oscillators (with hand at mid volume position) give difference frequency = 12kHz [unwanted 'ghost'] .. Filters roll-off audio above 10kHz, so this would not be heard (much)..

Pitch difference frequency [the audio you want to hear] is 5kHz, the difference between the [unwanted 'ghost'] tone and the [the audio you want to hear] is 7kHz, which could be annoying even if it is not actually heard as a ghost tone.

In fact, the above is grossly simplified, and probably unreasonable 'example' - all manner of nasty harmonics can be produced if one looks at all the possible spectral components, and the effect (if any) of these interactions will depend on theremin specifics - but the basic principle applies.

I know the above was an issue for me while developing my theremins - an issue I believe I have completely overcome by doing the volume sensing with a different circuit topology from usual.. It had thought that these issues I had were unique to my original design ( these problems are no big issue to correct on normal theremins.. I was experimenting with a theremin design which allowed automatic re-tuning of the oscillators to facilitate having multiple theremins playing in close proximity.. A version of Moog's IDIO Technology, if you like..;-) - But Jeffs comments got me wondering..

Posted: 4/8/2011 10:02:34 PM

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

Joined: 12/17/2010

Jeff wrote:

"Amethyste - When standing next to the volume loop, where is it in relation to your elbow? Are you comfortable when you play, or do you need to hold your elbow out to get enough height?"

Well Jeff, I have to extend my elbow out to play. It is not uncomfortable, but I think I could be more comfortable overall and that alone could do so much for my playing... I am going to TRY to record Pie Jesu tonight with tons and tons of mistakes, but you'd be able to gather a sense of my height in relation to my Theremin... Hmmmm... I so have a wodden box I could try to stand on and see how that goes for sound...

Stay tuned (haha no pun intended)
Posted: 4/8/2011 11:22:22 PM

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

Joined: 12/17/2010

okay... here we go...
Please be kind :) I've only been playing for a couple of months - i had to stop practicing for a bit because of my carpel tunnel, which is doing much better now :)


Pie Jesu (
Posted: 4/9/2011 12:11:53 AM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

Very nice.

Thanks for the video. It does show that you are positioned quite low relative to the theremin. In fact it appears that your pitch hand is actually below the base of the pitch antenna.

If I'm not mistaken, one would achieve the most consistant results playing pitch towards the middle of the antenna. In which case, you would need to be raised up quite a bit. It would also likely make playing the expression loop easier when you get to that point in your progression.

BTW...I love your vocal rendition. I look forward to hearing it in its "finished" state.

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