strange interactions between theremins

Posted: 5/11/2007 12:41:54 PM
Thomas Grillo

From: Jackson Mississippi

Joined: 8/13/2006

Anyone know what causes this?

I went to play my pro today, and noticed the pitch could not be adjusted to zero, until I realized my E Standard was parked too close to the Pro's pitch antenna. When I moved the Standard back everthing was fine, but here's the strange part.

I did a little experiment to see what would happen if I put the standard back in the close quarters position, and listened to the note. Then, I unpluged the power from the standard, and the note went down a step, until I pluged the standard back in. I'm sure that has to do with grounding.

Next, I removed the standard from the room, and brought in a large metal tripod, and parked it in the same place where the Standard was, but noticed the note played was such that I could adjust to zero with a little room to spare on the pitch knob.

Surely that tripod wis more massive than the E standard. Could it be that the tripod, being aluminum, and not of the same metal as the Standard's antenna have to do with this difference in interferance? Or is it the circuitry inside the Standard?
Posted: 5/12/2007 9:12:37 AM
omhoge

From: New York, NY

Joined: 2/13/2005

Checking the ground is usually good, and solid things can impact the fields, but theremins also just interfere with each other. And in many and sometimes unpredictable ways.
They can produce a sort of ring modulation.
Sometimes they will cross-control each other.
This is a perennial problem at NYTS, and happened whenever I've tried playing with another thereminist.

Basically the best we can do is:
Keeping as much distance between them.
Tuning your fields as tight in as practical.
Adjusting the theremins in various positions, e.g. loops towards each other, rods towards each other, loop to rod or different angles, etc. One time a pair of EWPros worked best with loops facing, another time two Standards worked with rods facing.

Maybe the Standard was interfering simply being plugged in, pitch impact is something that happened every time.

There may be an old thread here... I'll look.

hth
Posted: 5/14/2007 10:33:22 AM
DiggyDog

From: Jax, FL

Joined: 2/14/2005

The only time I have ever played with another theremin is with a guy who made noises on a one-stick in Barnyard.

He was usually several feet from me so there was never any problem.

I had never heard of the ring modulation thing before. That sounds kind of cool, although unpredictable.
Posted: 5/14/2007 10:37:25 AM
vonbuck

From: new haven ct.

Joined: 7/8/2005

i only have a problem when my Pro and wavefront are both on and aligned in a certain way. If the pitch antennas are aligned to each other, when you hold a note on the Pro it constantly jumps up and down a half step really fast. An intereseting effect, but unplayable

Andy
Posted: 5/14/2007 11:41:02 AM
Thomas Grillo

From: Jackson Mississippi

Joined: 8/13/2006

That's really strange. Which wavefront do you have?
Posted: 5/14/2007 11:51:30 AM
vonbuck

From: new haven ct.

Joined: 7/8/2005

Wavefront classic

Andy
Posted: 5/14/2007 11:54:04 AM
Thomas Grillo

From: Jackson Mississippi

Joined: 8/13/2006

NICE! I'd like to see that in action. I came "this" close to getting one, but went with the pro instead.
Posted: 5/14/2007 12:37:19 PM
vonbuck

From: new haven ct.

Joined: 7/8/2005

I got the Wavefront first, and love it. The trouble is it's a little awkward to move around to gigs. It's a hard shape to get a case for, and you have to screw in the legs. I wanted something more portable and more playable than a standard. Luckily when the Pro was anounced, I had a store credit at Moog, so I ordered one of them. It's a lot easier to set up and move for regular gigs.
I use the Wavefront for more formal occassions. But mostly I keep the classic set up in the music room under my theremin posters.
Andy

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