The Theremin in Winter

Posted: 12/18/2005 12:05:33 AM
Brian R

From: Somerville, MA

Joined: 10/7/2005

Recently the pitch control zone for my standard Etherwave seems to have shrunk.

Normally, I've played with the "Pitch" knob around the 9:00 or 10:00 position, to set the zero beat just in front of my body. As of this week, that doesn't work... in fact, with the knob turned fully counterclockwise, zero beat lies around HALFWAY between my chest and the pitch antenna, instead of somewhere just behind me. So the instrument's full ambitus is mapped onto a foot-and-a-half of airspace... you can imagine how this complicates the task of playing melodies accurately!

This change seems to coincide with the arrival of winter weather (my apartment isn't properly insulated, and the thermostat is in another unit)... has anyone else experienced this phenomenon?
Posted: 12/18/2005 3:58:36 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

P.S. Hmmm, that doesn't sound like much of a problem, does it?

That's because I was guesstimating distance, away from the theremin... and quite badly.

At present, the farthest I can get zero beat is about eight inches away from the pitch antenna. Aack!
Posted: 12/18/2005 5:04:46 PM
kkissinger

From: Kansas City, Mo.

Joined: 8/23/2005

Terracaster,

Though winter has arrived here in Kansas City, I haven't had any problems tuning my Theremins (an Epro and a Tmax).

I spose it is possible that you have a loose antenna connection or some other physical problem causing the loss of range. You may want to scrutinize the solder joints between the circuit board and your pitch control knob. It is possible that a cold joint was waiting for the temperature change (and the resulting contraction of metal) to rear its ugly head. Cold joints can in reality be "loose" joints... and a microscopic movement of such a joint will cause intermittant problems.

You didn't mention if you built your Etherwave from a kit... if you didn't and it is still under warranty, then you may want to contact Moog about the situation.
Posted: 12/18/2005 5:11:23 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

Thanks for the suggestion! I did assemble it from a kit, so I'll crack it open and check the solder joints.
Posted: 12/18/2005 5:16:26 PM
kkissinger

From: Kansas City, Mo.

Joined: 8/23/2005

I forgot to mention to check the lead from the circuit board to your pitch antenna, too.

Looking forward to hearing if you find the pblm. keep us posted.
Posted: 12/19/2005 11:02:29 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

D'oh! Revisited all the solder joints with a hot iron, but no restoration of proper control zone. In the interest of gathering reliable data, I'll try the instrument in a space other (i.e., warmer) than my apartment.
Posted: 12/20/2005 6:28:08 AM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

Temperature could certainly play a role in this, but I'm a bit surprised it's that drastic. In addition to impacting the characteristics of the capacitor your hand forms with the antenna, it could effect every other component in the theremin as well. Once your theremin warms up for a few minutes, is it still as bad?
Posted: 12/20/2005 9:01:24 AM
Brian R

From: Somerville, MA

Joined: 10/7/2005

Yup: the control zone is shortened, even after half an hour (or more) of operation.
Posted: 12/20/2005 5:14:04 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

Confirmed: Even in a warmer (and less confined) space, still the zero beat too close to the antenna.

Just so's you know: I contacted Moog Music about this, and they promptly replied, with the suggestion to retune the instrument and see how well it holds calibration.

My holiday schedule is very tight, so I probably won't get to attempt the adjustment until next Monday. I'll post an update when I have anything to report.

Thanks again to all for your input!
Posted: 4/14/2006 1:47:35 AM
kkissinger

From: Kansas City, Mo.

Joined: 8/23/2005

Hi, Teracaster and congratulations on your Valentine's Day performance!

Apparently your Theremin has settled-down and is working well for you.

Did you ever find out what was causing your pitch-control/tuning problems?

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