Totally failed experiment...lesson learned?

Posted: 1/9/2009 9:58:21 AM
podmo

From: Cincinnati, OH

Joined: 1/1/2009

Today, while my wife was in the shower so she wouldn't hear me and make fun of me, I tried playing bottleneck guitar in a manner that moved my hand and the slide in in relation to the pitch antenna. My perhaps obvious discovery was that it didn't make the least difference to the theremin where my hand was, but only how close the closest part of the guitar (always the headstock) was to the antenna. This raises questions, based on an assumption:

If the player/antenna form the plates of a variable capacitor as the means of adjusting pitch (the assumption...true?), does it make any difference what the surface area and composition of the conductor are on the player side of the equation?

If the answer is "no", then is proximity to the pitch antenna the only thing that counts (the closest point of approach of the closest fingertip)? Do the "follower fingers" contribute nothing? If so, could someone with only an index finger play just as well as someone with a complete set? If so, what are the implications on knuckle extension and fingering techniques? Does only the longest (closest) finger get to play, in actuality?

I am pleasantly puzzled.

Pod
Posted: 1/9/2009 10:00:57 AM
podmo

From: Cincinnati, OH

Joined: 1/1/2009

By the way, the experiment sounded like I was strangling a cat while cheerfully playing "Poor Boy, a Long Way From Home". I am sooooo grateful that no one heard.

Pod
Posted: 1/9/2009 10:42:27 AM
omhoge

From: New York, NY

Joined: 2/13/2005

Play is the best way to discover!
Anything in the playing field with mass that can change the capacitance of the of the circuit will change the pitch or volume. Hold a bottle of water near it and it'll change, a piece of paper won't.

The Theremin is a remarkably barrier free instrument, several people with different physical conditions have discovered very successful ways to make music with it. One fellow, it's in the archives here somewhere, was able to use his knee to control the volume loop.

And some of our TW members have been known to wave any body part, or spoon (see schielenkrahe's [Kip Rosser] fantastic 1/13/2006 exercise (http://www.thereminworld.com/forum.asp?cmd=p&T=1630&F=557&p=1)) and even egg beaters at the thing!
Like Gordon's famous twangulator piece
http://myspace.com/beatfrequencyuk
(that's it right? I have trouble playing my space or you tube videos)

Yes the closest finger is important but you may think of the shape of the hand more. There's also a great discussion in the Aerial Fingering Technique (http://www.thereminworld.com/forum.asp?cmd=p&T=1391&F=780) thread.

hth...
Keep on Playing!
Posted: 1/9/2009 11:30:01 AM
carport888

From: Redmond, WA

Joined: 9/1/2007

Pod,
The Theremin fields are affected by anything with capacitance, but the object with the most capacitance closest to the antennae will affect them the most, whether it be your guitar or your closest finger.

As an experiment, rest your hand on the Theremin a few inches from the pitch rod and sway your body. You'll notice that your body, although it is not the closest object to the rod, has enough capacitance (more than your hand) to affect the pitch. This is why good breathing technique and posture is important to Theremin playing.

Since your guitar was closest, and has a lot of capacitance, your hand was not as prominent within the field. As another experiment, try tuning the Theremin down while your guitar is within the field so that you can achieve zero beat as though there were no guitar. Your hand should now have more of an effect over the pitch.

A few months ago, I visited the Pacific Science Center in Seattle, Washington, where they have a theremin on display. However, tuned tightly, it was encased in a protective shell, with no accessible knobs, so I used soda bottles (http://www.youtube.com/watch?v=qmk2Hlwpl3s) to expand the field. they had just enough capacitance to expand the pitch to a playable range, but not enough to negate everything else in the field.

~Dan
Posted: 1/9/2009 12:57:46 PM
GordonC

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Omhoge mentioned twangulators.

This mySpace video (http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=1445538) of The Plummeting Man includes a couple of brief shots of use of the Frothatrill (electromechanical frequency modulation) at 2:26 and Twangulator (electromechanical envelope shaping) at 2:51.
Posted: 1/9/2009 4:27:19 PM
coalport

From: Canada

Joined: 8/1/2008

In the following YooChoob vid I used the neck of a musical instrument (my surbahar) to control a Moog Ethervox theremin since my hands were occupied.

Of course, I was not trying to play accurate tones with the theremin, I was using it to control a MIDI device (a Roland JV 2080) but the "space control" capacitance principle is the same.

Since there was no way to control the volume antenna I had to use a potentiometer that is on the floor to my left. I also used a GROUND CONTROL MIDI controller for Ethervox program changes which I did with my right foot.

The whole thing turned out to be a bit of a circus act but it was fun.

http://www.youtube.com/watch?v=zCCSuU7kXM8

Posted: 1/9/2009 6:58:41 PM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

podmo said:

[i]“I am pleasantly puzzled.” [/i]

You see more clearly than most and have made an astute observation and you are to be commended for it. If the heterodyne theremin was responding to the hand acting as a capacitor plate then "why" if you reach forward palm facing the antenna with one hand behind the other, then slide the rear hand over next to the other but but not any closer does the pitch remain the same? (Edit: This scenario contradicts that the hand acts as a capacitor plate.)

A “perfectly linear” pitch field has always been available to those who could see beyond the hand capacitance factoid.

The heterodyne theremin responds to conductivity or absorption in the transfer of energy away from the pitch antenna. The principle is exactly like those high frequency plasma gas globes where your finger attracts the energy in the globe which searches for the easiest path to travel. It would be incorrect to even call this energy flow because the energy transfers near the speed of light so it is basically instantaneous. The energy of the heterodyne theremin focuses in on the least resistant point which would be your forward finger tip with very little influence of anything behind it at that specific location in the pitch field.

There are true hand capacitance theremins which must use a metal plate but they will lack sensitivity to aerial fingering, this is why little if any quality music is being charmed from them.

Christopher
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Posted: 1/10/2009 8:23:36 AM
coalport

From: Canada

Joined: 8/1/2008

RS Theremin wrote:

"If the heterodyne theremin was responding to the hand acting as a capacitor plate then why if you reach forward palm facing the antenna with one hand behind the other, then slide the rear hand over but not any closer does the pitch remain the same?"

*****************

One of the essential elements of theremin technique for a serious precision player is to learn to change the configuration of the pitch hand within the static electric field without audibly changing the note.

Let's say you want to change your hand configuration inaudibly from a "fist" to a "fan" (something you might want to do in anticipation of a jump to the next note). You can do it by learning to move, very slightly, the geographical position of your hand within the playing arc as you change your configuration. The thrusting forward of the fingers is counterbalanced by a simultaneous but MINUTE shift of the hand away from the antenna (or vice versa).

One movement compensates for the other so you are actually moving within the EM field without causing any identifiable change in pitch. It's like the old Shaolin discipline of learning to walk on rice paper without leaving a trace.

The secret of both is butterflies.

Posted: 1/10/2009 9:23:07 AM
Thomas Grillo

From: Jackson Mississippi

Joined: 8/13/2006

On the subject of capacitence, I've completed, and will be uploading a short video of what happens when a remote control helicopter is flown into the pitch field of a theremin. The toy did trip the theremin, but I have to wonder if my body's location in the zero beat zone was enough to provide sufficient capacitence, and ground to allow the towy to trip the theremin.
Posted: 1/10/2009 9:25:34 AM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

The proper term for control of the heterodyne theremin should be “Radiation Resistance” and this should replace the improper use of the term hand capacitance.

Though future generations will view this as resistance occurring between your hand and the antenna, it actually refers to the “marvel in physics” of the antenna current transforming into radiated electro-magnetic energy at the antenna. Radiation resistance is the total RF electro-magnetic power radiated divided by the square of the net current flowing into the antenna that creates the radiated energy. The pitch field must be viewed as a dual electrical/magnetic equilibrium, not just a capacitive field.

Changes in the antenna current have a direct affect on the “capacitance reactance” Xc of the pitch oscillator and this is what causes heterodyne theremin pitch change.

Christopher

edit: My last comment here: "The Theremin Pitch Field" (http://www.thereminworld.com/forum.asp?cmd=p&T=3751&F=1)
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