Tuning/Calibration issue

Posted: 12/28/2015 5:23:27 PM
drhodes

Joined: 12/28/2015

I received a Etherwave for Christmas. With the pitch knob all the way counterclockwise, regardless of angle of my body to the instrument, I cannot find a zero beat point more than a few inches away from the pitch antenna. I'm practically on top of the instrument to have the lowest pitch anywhere near my body. The instructions in the manual read "slowly turn the pitch tuning knob clockwise. You will hear the tone's pitch go down." When I turn the pitch knob clockwise, the pitch ascends. I've done everything the manual says (multiple times), watched videos online, read various forums and blogs and tried everything suggested, but am still at a loss. I'm so looking forward to expanding my own and my students musical experiences and compositions - I'm a college music prof - with the theremin, but the set up has me baffled. What am I doing incorrectly?

Posted: 12/28/2015 5:39:49 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Is it mounted on a microphone stand or is it sitting on a table?  A table can really throw off EW tuning.

Do you have it properly grounded?

Posted: 12/28/2015 6:10:37 PM
drhodes

Joined: 12/28/2015

Thanks for your quick reply. Yes, it is mounted on a microphone stand and both the instrument and amp are plugged into grounded outlets. Is the Moog manual incorrect that the pitch knob should lower the pitch as you turn it clockwise? That seems counter-intuitive to me, it seems as though counterclockwise would lower the pitch and clockwise should raise it. 

 

Posted: 12/28/2015 6:51:41 PM
mpampouras

From: Epalinges, Switzerland

Joined: 3/15/2005

Seems like it is completely out of tune, maybe you have to open it and adjust / calibrate the pitch coil?

In the Kees there is an external pitch knob that does exactly that, but in the EW I think that you have to open the instrument to do that.

Posted: 12/28/2015 7:19:09 PM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

Hello dr,

dewster is right on about grounding, we are talking about devices with 3-prong plugs.

I retired from my theremin research earlier this year but I sure do miss it. This webpage of mine has the answer to tuning. When the wood top is taken off the EWS it will shift the tuning. To compensate for this shift with lid off take a 8" - 22 gauge wire, fold it into a horseshoe and hang it off the antenna. Then tune L6 the middle IF-transformer for an ideal Null. Avoid L5 as this is in tune with the antenna circuit, have the pitch knob set half way.  

Take the horseshoe off once the lid is back in place, you just might get lucky!

Thanks xtheremin8 for the L5 & L6 correction, old age is not doing me any favors.

Theremin Tuning

Christopher

PS: The horseshoe wire can also be a temporary fix when the Null Point is too close to the antenna, a tight pitch field. The wire pushes the Null point away from the antenna, so twist and snip a little shorter to move Null towards the antenna, a little longer to push Null away from the antenna.

Posted: 12/28/2015 11:57:12 PM
xtheremin8

From: züriCH

Joined: 3/15/2014

@christopher: i think you mixed up L5 (far right) and L6 (middle one) in your post. sorry for my peacounting ;-)

Posted: 12/29/2015 2:36:05 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Drhodes, if you plan on owning this Etherwave long-term I recommend you drill small holes in the top to tune it through.  Taking off the top to tune it, putting the top back on to see how it messes with the tuning, taking the top back off to tweak it, etc. is pretty tedious business.  Not sure why Moog didn't put holes there in the first place.

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