Etherwave Pitch changes with Cover On

I just finished building an Etherwave Plus Kit with the ESPE01 installed.  I tested it and tunes the L6 before placing the cover on and it sounds perfect (with the whole pitch range in front of me).  When I put the cover on and power it back up, the pitch gets much higher and there is no zero beat even when I back away.  The L6 tuning seems to have to affect once I put the cover.  I have to turn the tuning knob almost all the way to the right to compensate but then I can only get a very low register.  Any suggestions?

-Jared 

Hello Jared,

Before an engineer says drill holes in the box... try this.

Have about an 8" wire looped around the base of the antenna when cover is off. Remove wire when cover is placed back on.

Shorten the wire a bit to get the balance perfect.

Ignore those big brackets, it was another experiment.

Christopher

Hi Jared,

You can just set the cover upside down on top to see how it affects the tuning.  That's how I do it anyway.

The cover is held together internally with 9 screws. These add to the capacitance seen by the pitch antenna. The simplest way to come close to good results is to tune L6 for zero beat with the right elbow at 10cm or 4 inch from the pitch antenna while adjusting L6 and with the pitch knob set to half to twelve. Afterwards, you might still two or three times remove and put back the cover to fine-tune L6 until everything is really perfect. Afterwards, fix the cover with its 4 screws and you'll see that you have to turn the pitch knob from 11h30 to 12h00 to compensate the effect of these screws.

Thank you! These have helped. I have my zero beat right about where it should be, but the range seems to be in a very low octave.  Is there a good method for setting where my highest note should be? I’ve adjusted the L5 coil a little but still can seem to get a good range.

Tuning L5 to optimize the pitch range and linearity is extremely tricky, doing something wrong might make the variable oscillator jump on a side resonance or seeing an overload through the series resonant circuit formed by the linearization coils and the antenna capacitance. If you have a video call tool like Skype or FaceTime, I might guide you through that process. You can contact me either via PM here or on Facebook Messenger.

Thierry what is the image in your avatar picture?

Jared, I leave you in Thierry's hands as the variable oscillator must be tuned "slightly above" what the antenna circuit is tuned to. Then a little more tweaking to get it right. One day the Electrodeum a phenomenon, will catch on and all the fine tuning for linearity will be a thing of the past. Then "all" theremins will play the same between models so focus can be on sound and technique.

If the frequency of the antenna circuit is tuned above the variable oscillator you will get a flat spot in the pitch sound when the antenna frequency crosses over the variable oscillator frequency. I think that might be why you are getting the results of a narrow range that you are getting right now, just my opinion.

Antenna tuning is a bit in the Alchemy realm.

Christopher

Christopher, the picture in my avatar is a drawing which the Swiss artist (designer and poet) Catherine Jan made from me during a public lecture which I gave in her area. She sent it to me afterwards, together with some pictures she had taken from me and a poem about touchless music.

"Tuning L5 to optimize the pitch range and linearity is extremely tricky, doing something wrong might make the variable oscillator jump on a side resonance or seeing an overload through the series resonant circuit formed by the linearization coils and the antenna capacitance."  - Thierry

IMO the EW is really just way too difficult to tune.  I can't believe they sell the thing, much less offer it as a kit.  Nearfield linearization via two LC resonances "fighting each other" was OK I suppose back in the day when there were no alternatives, and when the trimming C was located at the antenna, but it's a bear to setup and maintain.

Thierry, a FaceTime session would be so helpful. My email is ###edited_to_prevent_spam###
If you’re able to find a good time.

Thanks!