# Close / Far Pitch Antennas?

Posted: 5/10/2012 6:58:27 PM

From: Jackson Mississippi

Joined: 8/13/2006

@RS Theremin: This would be great when run with a theremin equipped with pitch preview, especially for those of us with only relative pitch but can read music. 1/10th sec sampling should be fast enough to work with on the fly with no problems. Otherwise it's a great tool for learning notes on the theremin. I wrote a thread on this sort of tech a while back regarding Sing & See software which works on this principle, albeit libited to human voice range in terms of sensitivity of frequencies. Thanks for posting this.

Posted: 5/10/2012 9:35:40 PM

From: Colmar, France

Joined: 12/31/2007

Perhaps I misunderstood Mr. Nyquist and his theorems. With 1/10s of sampling interval, the frequency can only be measured with an accuracy of +/- 10Hz. But the display shows even one digit on the right side of the decimal point which would require a sampling interval of 10s to be accurate.

Is there some magic?

Posted: 5/10/2012 10:08:50 PM

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

@Thierry - I said in the post with the graphic that "the UK has talent", after your observation  I guess I will go back to the previous comment of "Why is Europe backward".

Anyone interested use this simple webpage to test the displayed accuracy. Between this tone source and the Tuner accuracy it is better than I can hear!

A 40 Hz tone displays consistently at 39.8 Hz

A 440 Hz = 438 Hz, yes magic!   Both samples are 99.5% accurate. Lets not be anal.

William Steer PhD in England says it is 100 ms sampling. I validate it as fast refreshing!

Posted: 5/11/2012 4:10:59 AM

From: Northern NJ, USA

Joined: 2/17/2012

"Perhaps I misunderstood Mr. Nyquist and his theorems. With 1/10s of sampling interval, the frequency can only be measured with an accuracy of +/- 10Hz. But the display shows even one digit on the right side of the decimal point which would require a sampling interval of 10s to be accurate.

Is there some magic?"

[Edited to remove unintended negative tone] There's a difference between measurement accuracy and precision of calculations, perhaps that's the deal here?

And perhaps there is a bit of averaging going on over multiple measurement periods?  The DPLL on my digital Theremin can only resolve the phase error in a single cycle to 20ns (the 50MHz master clock period) but averaging allows it to resolve way finer than this.  The NCO employs phase dithering for similarly increased output frequency resolution and spur reduction over multiple cycles, much like a delta sigma modulator.

Posted: 5/11/2012 5:51:37 PM

From: Weert, Limburg, the Netherlands

Joined: 4/10/2012

Sofar, I preferre my EW ;-) Well ... I once started with this little Jaycar (Ugha!), but EWs are MUCH easier & more relaxed to play!

What you mention, Thomas, about EWs and the heights of the pitch antenna and the volume loop antenna actually IS somewhat true, but it doesn't truly bother me, as I know it's only a little "issue", but I slved this by playing in a broad way ... Possibly more broader than averagely (not hard for me as I'm a quite short, broad and short armed person LOL!) ...

Nevertheless, the setup and adjustments of your pitchfield range is another matter ... I think that everyone overhere preferres his/her own preferrences into this, but I always be sure that the lowest tone of a song's melody is somewhere some inch in front of my chest, so, the highest tone is somewhere an under arm length away, but as I play a bit broad, the lowest tone also can sometimes go a bit aside body (corp) level ;-)

Posted: 5/11/2012 6:28:47 PM

From: Jackson Mississippi

Joined: 8/13/2006

@Yeapsyster: Hi, That's certainly a good way to tune for a given piece. After the install of the enhancement module, I have to set zero beat out to near the end of the volume antenna to account for the extra notes the module adds, but I am able to tune so that I can get the octave jumps if I open and close my fist. I'm often somewhere in the middle of the plus zone ever since the module went in. Does take a little getting used to, but it's well worth it. :)

Posted: 5/11/2012 8:49:29 PM

From: Weert, Limburg, the Netherlands

Joined: 4/10/2012

@Yeapsyster: Hi, That's certainly a good way to tune for a given piece. After the install of the enhancement module, I have to set zero beat out to near the end of the volume antenna to account for the extra notes the module adds, but I am able to tune so that I can get the octave jumps if I open and close my fist. I'm often somewhere in the middle of the plus zone ever since the module went in. Does take a little getting used to, but it's well worth it. :)

---

... Thomas ... ;-) What you mentioned about the octave and one fist, I do this with some songs (with large jumps in it) too ... And I can imagine that things are changed since you have this great module! (Still wanting a bass module for my EW as I think this mopet bass humming in some songs isn't that nice at all LOL!)

... And yes ... I can imagine that some people prefer other ways of tuning, as no person is the same and a theremin always react in a different way on different persons, like the ether seems to "know" people can have all shapes, widts and lengths ... Some people have longer arms, other shorter arms, some are short and fat (like me) and others are long and tall, so, it won't say that my way of adjusting is a good way for others ... We only can share some tips & tricks eh?

Love,

Marielle :D

Posted: 5/12/2012 9:50:43 PM

From: Colmar, France

Joined: 12/31/2007

I think that there are no rules in general, a lot depends on the instrument and on the player and his posture.

Two examples:

a) The Moog Etherwave Pro can be adjusted and tuned for somewhat more than 5 absolutely linear octaves. I did that a few years ago for Carolina Eyck, standing myself in a respectful distance to her precious instrument, at my arm's length from the pitch antenna. When Carolina came to check and pick up her instrument, she first took her chair and finished up sitting very close, the right knee almost below the pitch arm. Ugggh! The lower octaves were atrociously stretched now and I had to take the screwdriver again and needed another hour of fine tuning until she was finally very satisfied with the result.

b) The Russian tVox tour theremin has no "classic" linearization coils. But thanks to the very thick antenna, the metal bottom plate of the housing and the low oscillator frequency (135kHz), the higher range is not as compressed as one would expect, but the tone spacing is definitely shrinking somewhat the closer you put your hand to the antenna. But the middle and lower end of the pitch field can be perfectly linear thanks to a very sophisticated circuit which controls a dynamic coupling between the oscillators. The simplest way to stretch the pitch field in the high register is approaching your body to the pitch antenna. You have to learn to move your body with the register. Thus you use the pitch knob to adjust for your wanted tone spacing in the middle register when your body is in normal position. The control circuit must only be adjusted once with a hidden potentiometer to keep the tone spacing constant in the lowest register depending on the players' moving away from the center position in a symmetrical way as he moves closer when he plays high tones. Every tVox owner will find that there is a learning time until he found for himself a consistent way to move his body according the register and the optimal adjustment of the control circuit.

Posted: 5/13/2012 1:00:15 PM

From: Northern NJ, USA

Joined: 2/17/2012

Thierry, thanks so much for that in-depth and fascinating tVox technical info!  You must know more about analog Theremins than anyone alive (or dead).