Calibrating pitch

Hi everyone! I am pretty sure that my theremin's pitch oscillators need to be calibrated, and I wanted to check here before trying anything dangerous!

The lower end of the pitch range has been slowly creeping upward, so now the range is only about 2.5 octaves or so. This makes the intervals very spread out unless I adjust the pitch tuning so that I am playing very close to the antenna. Either way, it is not good and makes playing more difficult that it should be...

I have read Moog's guide to "hot-rodding" a theremin where it covers tuning the pitch circuit, and I would like to confirm that these instructions are in fact correct.

http://www.moogmusic.com/support/faqs/#etherwave%25C2%25AE-theremin-faq

Also what is the ideal range for an Etherwave Standard without the ESPE01 module? I imagine 4 or 5 octaves?

Thanks in advance for any help. I really appreciate it!

These are the instructions I am referring to:

"follow these steps to adjust L5 and L6:

1. Set P1 (the Pitch Tuning control) to its mid-position.
2. Grasp and hold the pitch antenna with one hand. With the other hand, adjust L6 for zero beat. (Note: If the slug in L5 is fully counterclockwise, you have to turn it clockwise a turn or so in order to hear zero beat.) Then carefully turn L6 counterclockwise until you hear a pitch of about 3 kHz (3 1/2 octaves above middle C).
3. Let go of the pitch antenna. Slowly retract your hand from the vicinity of the antenna. You will hear the pitch go down. If the pitch does not go down to zero beat when you've retracted your hand completely and stepped back, then L5 is set to too low an inductance. Advance the slug in L5 (that is, turn it clockwise) a small amount, perhaps 1/10 turn or so, and repeat steps 2 and 3. If the pitch goes to zero beat and then begins to ascend as you retract your hand, then L5 is set to too high an inductance. Turn the slug in L5 counterclockwise a small amount, and repeat steps 2 and 3.
If the pitch jumps abruptly to a very different pitch as you retract your hand, then L5 is set to far too high an inductance. Turn the slug in L5 counterclockwise, perhaps 1/4 turn, and repeat steps 2 and 3. Eventually you will converge on the proper settings of L5 and L6. The idea is to achieve settings in which the pitch is at zero beat when you've stepped away from the theremin, begins to ascend when your body is about 24" from the pitch antenna, and is about 3 kHz when your hand touches the pitch antenna. Tap lightly on L5 and L6 as you converge on the proper settings, as this will stabilize the tuning slug positions.

This completes the tuning of the Pitch Oscillators. In performance, the exact pitch tuning is achieved by adjusting the Pitch Tuning control."

Also I realize that many people are at Hands Off 2011, so I may have to wait for a response! :)

When the hot ridding manual has been written, they didn't yet know that they would use different variable coils some years later. Those newer ones with the hexagonal holes in the slugs behave in a totally different way.

A question in this context: If the engine of your car isn't running well, do you start fiddling around with the timing of the fuel injection or the ignition? You most probably will not take the risk but rather see an expert for that. Why do you then want to take the risk of (completely de-)tuning your theremin yourself without any experience in this domain?

I think she is here asking for help?

Thierry, what is your suggestion?

Hello, Thierry! How are you? Do not worry, I have not fiddled with anything. I'm still trying to research this, which is why I posted here. Ideally I would send my theremin to an expert who could completely recalibrate everything, but unfortunately that does not seem to be an option.

So what is your suggestion for this issue? If it is not a major repair, I would like to learn to make the adjustment. Thank you!

The option would be sending your theremin (just the box without antennas and power supply) to me, get it not only fixed but optimized and then sent back.

Thierry, you would definitely be the best person to make any adjustments or repairs. Since I am in the States, I do have some concerns about shipping the theremin overseas. I will send you a private email with my questions. Thanks!

Rachel,

I had to ship my sold Etherwave to its new owner in Spain. Here is what I did to keep the cost down.

If you are worried about packing your instrument yourself, you can take your etherwave to a packing place (here we have Mailbox etc and others). They charged me $15 to pack it. It was well done! Then take that package to the USPS store and ship it from there - NOT from the packing place. The packing place charged $40 MORE than USPS. With Insurance to Spain, it was $50.65. It got there in 5 or 6 days.

Hope this helps :)

Thanks for the tip, Amey! I will be sending it tomorrow. :)

My pleasure :)
Sending lots of warm thoughts for your theremin's journey (cheesy huh? lol)