Fixing Claravox volume antenna

You might try the calibration for high and low volume on both modes even though they only recommend high and low volume on modern mode.  I did this and mine seems to work well. Mine is number 333.
Good luck.  I go between both modes.  They each have their own character.
Hope you resolve your issues.
Thanks 

Hi,
Thanks for your help.
I just tried that but there is absolutely no change.
I made the "near" calibration with my hand approximately one inch above the loop.
A faint sound is still there even with my hand inside the loop.

Let's check the procedure.
- "Far" volume :
Mode switch on "traditional" (down).
Register knob on position 2.
Main output switch on "active" position (up).
I enter the calibration mode by pressing store and set root buttons until both LEDs blink.
Then I place my left hand up at maximum volume position and press the "store" button.
I stay still until the LED stops blinking.

"Near" volume :
Mode switch on "traditional" (down).
Register knob on position 2.
Main output switch on "mute" position (down).
I enter the calibration mode by pressing store and set root buttons until both LEDs blink.
Then I place my left hand just above the loop and press the "store" button.
I stay still until the LED stops blinking.

Is that correct ?

For the moment, the best solution I found is to set the volume knob to maximum in order to get a maximum volume and reduce the volume on my amp.
This also reduces the volume when my hand is in the loop, but I still hear it !

Serial number 01715.

My understanding is that Moog considers this correct behavior; zero volume only when actually touching the antenna.

You can get a noise gate and set it to a very low threshold to kluge around this; that’s what I did. Lame, I know

I hope Moog will not answer that !

I have an Etherwave standard that completely and smoothly mutes the output.
Same for my Claravox in modern mode.

Even when touching the antenna of the Claravox, I still hear the sound.
Worse, when I touch the antenna, the pitch goes down by one tone !

It is a bug. Or a wrong internal setting. Or a faulty component. Or a faulty design.

Just found an interesting statement from Moog, as an answer to Jason's questions in this subject (third message on the page) :

http://www.thereminworld.com/Forums/T/33270/post-your-questions-about-the-claravox-centennial-here?Page=1

"Traditional mode...

The Volume oscillator has a traditional diode rectifier circuit that is highly filtered to fully isolate the DC component but also allow for very quick dynamic response which is used to modify a very high-SNR voltage-controlled amplifier (VCA).  As such, the Claravox has a very large dynamic range and low-noise floor allowing for both very pure sonics but also a large range of dynamic response for different playing styles."

"Even when touching the antenna of the Claravox, I still hear the sound."  - André

Unfortunately this seems to be a common problem with the Cvox.

"Worse, when I touch the antenna, the pitch goes down by one tone !"

This is probably rather normal for most Theremins, touching the antenna alters your body grounding, and any little thing will disturb the pitch side (I've seen it written that pitch is our finest sense).

"It is a bug. Or a wrong internal setting. Or a faulty component. Or a faulty design."

Can I get an "all of the above"?  Well, I don't actually think it is a faulty component, more a design that has little to no margin for the deep silence region.  Sound leakage is one of those things that Theremin designers need to really watch out for, it's bit me more than once.  I have no idea why Moog didn't use "Modern" mode exclusively for the volume side, they could have sidestepped all of this trouble.  Hindsight is 20/20 I suppose, but I wonder if they could address this in software?

You might try following the steps at the end of this post: http://www.thereminworld.com/forums/T/33487?post=221156#221156

A proposed volume loop "tuning" procedure sans equipment:

0. Ensure volume loop connectivity (remove the varnish from the end up to the locking studs with acetone or sandpaper).
1. Put the Claravox in "Traditional" mode.
2. Set the "Volume Antenna" knob to 12 noon (straight up).
3. Adjust the volume coil slug for maximum volume with your hand away from the volume loop (kinda hard to do while adjusting the slug!).
4. Wiggle the "Volume Antenna" knob to ensure maximum volume is around 12 noon, if not repeat step 3 & 4 until it is.

You may not have to adjust the coil slug much, try 1/8 turns at first.  I would recommend you put a piece of tape on the other end of the plastic hex tool to make a flag of sorts to indicate rotational position.  You might want to use some kind of visual indication regarding maximum volume (VU meter, Audacity recording envelope, etc.)

I'd be interested to know if that helps at all.  If you aren't getting full silence you don't have a lot to lose by monkeying with it at this point (famous last words).

Hi Eric, thanks a lot for this detailed reply.

"Worse, when I touch the antenna, the pitch goes down by one tone !"

This is probably rather normal for most Theremins

I agree, Il was just replying to Bendra :

My understanding is that Moog considers this correct behavior; zero volume only when actually touching the antenna.

I tried your volume loop tuning procedure "sans équipement".
I did "monkey" with the famous Moog red tool !
(thanks for this idiomatic expression that I didn't know )
I now better understand the effect of this adjustment on the volume response curve.

With the initial  setting (as received) the response curve was pretty strange, with a "knee" 3 to 4 inches above the loop and a range limited to 6 - 7 inches.
After some time of monkeying, I achieved a very linear curve and a larger range, similar to what I have with my Etherwave.
Thanks a lot for that anyway.

But whatever is the setup, the minimum sound level remains unchanged.
There a sort of "electronic stop" that can't be overriden, somewhere in the frequency to voltage converter or in the voltage controlled amplifier, probably.

I opened the back panel.
Looks like I bought a box full of air !
I found nothing that could be adjusted.

If I get no satisfactory answer or no answer at all from Moog, I might take my oscilloscope and frequency meter out of that cupboard where they are sleeping and try to go deeper into that empty box !

"I opened the back panel.  Looks like I bought a box full of air !"  - André

Ha ha!  There is a lot of elbow room inside there...

You might take a look at issue #9 here: http://aetherwellen-musik.de/Theremin-Instrumente-Instruments/Claravox-Centennial-CV-C-Theremin-Review-Improvement.  I haven't tried it myself to see if there is any improvement, but it makes general good sense to keep the green antenna wire away from any ground planes.

Looks like Moog has heard of Aetherwellen issue 9.
Here are 3 pictures :
1 - Aetherwellen picture of green cable as from Moog.
2 - Aetherwellen modification.
3 - Inside my Claravox.

I don't know if 3 is better, worse than or equal to 2.

This is the way Moog keeps the green wires away from any ground plane, I suppose.
IMO, those wires should be as short as possible.
There is no reason to use such a long loop to connect the antennas to the circuits.