Theremin problem with pitch

Posted: 6/9/2006 10:48:30 AM

From: Morrisville, PA

Joined: 10/19/2005

Theremino, you wrote:

>As for the 12 o'clock setting of my pitch knob, I'm still not able to get that kind of setting as putting it at the 12o'clock setting only gives me this very high pitch octave where I have to move about 6inches to get from one diatonic note to another! I'm only able to get the "normal" hand pitch movement of playing a melody when this pitch knob is set to maximum (the 5o'clock position)!>

As I mentioned beofre, you actually CAN get that setting straightened out, but to do it you will have to OPEN UP your theremin.

The primary reason to make this adjustment is that if you're currently at one extreme end of the pitch knob's position, over time you will be unable to get zero beat at all. If the knob is turned as far clockwise as it will go just to achieve silence, as the pitch "slippage" occurs -- and it will -- you'll be unable to adjust the knob. It may be okay now, and it may take months to fully slip, BUT it could easily happen INSTANTLY if you change location for a performance or something. Then you'd really be in a fix.

I've yet to have to make this adjustment to the Etherwave Pro, and the procedure will be different than the one described below.

BUT -- if you have a STANDARD ETHERWAVE, here's what to do.

If you have the standard Etherwave, you'll be adjusting the fixed pitch coil, L6. With the theremin turned off, you unplug the power supply, open the lid and place it aside. Plug the power supply back in. Now, turn the theremin on and turn the pitch knob to 12 noon. It's going to make a lot of noise.

Next, using a little plastic screwdriver, you turn the pot at the top of the L6 coil a little clockwise, or a little counterclockwise until you get zero beat. Make a note of the "hour" position of that little screw slot. ( five o'clock, three o'clock, etc.)

Now, place the theremin lid UPSIDE DOWN on the theremin. This is to simulate the lid being on. The position of zero beat CHANGES the second you put the lid on. So, to get things as accurate as you can without constantly having to take the lid on off on off on off, while plugging and unplugging the power supply, etc., you place it on top upside down. You'll notice that zero beat is no longer where it just was anymore. So, you need to compensate for what will happen when the lid is on.

Here's an example: The last time I made the adjustment, about a year ago (the second time in about five years), the hour LID OFF position of the screw head on L6 was 4:00 to achieve zero beat. The LID ON position of zero beat using the pitch knob was then about 10:00. I turned the knob back to 12, then I followed the trial and error described below, turning the coil screw counterclockwise a little more each time, until zero beat ended up at 12. Without a lot of fancy equipment, here's the only way to do it:

Take the lid off and turn the L6 coil screw just a little bit ( whether counterclockwise or clockwise depends entirely upon your theremin, so you may err on one side or the other until you figure out which direction to turn it ). The theremin will begin to make a lot of noise, but that's okay. Put the lid back on upside down and see where you get zero beat by turning the pitch knob. Chances are it will be off by hours. Note the hour you get zero beat. Determine whether you'll need to go clockwise or counterclockwise with the pitch knob to get either clockwise TO or counterclockwise BACK TO 12 noon.

Repeat the process by putting the pitch knob back to 12 ( the theremin will squeal, but that's okay ).

You're going to go back and forth with lid on, lid off, adjusting the coil gently either clockwise or counterclockwise, then putting the lid on, and seeing if you can get zero beat right at 12 noon with the pitch knob.

Be patient, this DOES work. Once you've achieved it -- and it can take about a half hour -- now comes the real task. Unplug the power supply, put the lid on fully ( wit

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