Theremin grounding question

I purchased a theremin etherwave standard roughly two months ago and whenever I tried to use effects pedals I noticed that anytime I touched the pedals it increased to field so that the lowest note was far behind me (despite being in tune previously) only to go back to normal after i took my foot off the pedal.  The same thing happens if I touch the metal part at either end of the cable (theremin end or amp end) as well as the plate/surface with all the knobs on it on either the theremin or amp.  HOWEVER, it is a less drastic change if I touch the surface/plate on either the amp or theremin than it is if I touch the metal jack or cable.   Is this normal behavior because I'm beginning to get concerned that I have a faulty theremin.  This happens no matter where I play my theremin so it isn't a home wiring issue.  Also I've been told that this lack of grounding could also be making it harder to play as the linearity of pitch is probably skewed, would this be true?   I've had severe hand problems in the past that have forced me to give up my instrument, education, and career goals so I simply can't afford to be working harder than need be or working on hand positions that aren't going to apply if I get my theremin fixed.  Does the field greatly expand on YOUR theremin when you touch the metal part of the 1/4 inch cord?  It should be known that I (obviously..) don't know much about the technical stuff here, so a dumbed down answer would help, but I do have a friend who is much better with this kind of stuff so if need be I could forward a response to him. He is an electrical engineer however (and a musician), not a theremin player so keep that in mind.

That's an auto-protect mechanism of the theremin, which appears if people connect too early effects and pedals before they studied music and practiced the instrument systematically for years as recommended by the "grande dame" of the theremin, Clara Rockmore.

Troy,

I mentioned different countries are not grounded the same, that is why they drive on the wrong side of the road. You must decide which side you want your journey to travel. A hint, the finest Thereminist in the World drives on the right side and so did Clara's taxi driver most of the time. 0-'

Christopher

Himtroy,

Its simple - you need a good player coupling to ground!

Get a long audio lead, plug this into the theremin, lay it close to where you are standing or sitting.. or make a grounding mat!

Think of it this way - If you were standing on the pedal all the time, there wouldnt be a problem! --- So effectively make something to simulate standing on it all the time (extend the ground) !

 - But perhaps Thierry is right...... ;-)

Fred.

Thanks for the help.  As for the other comments (Thierry)...I've been studying music for a long time and was a pretty high level performing classical guitarist before I hurt my hand.  I have very good relative pitch and a very good understanding of music theory as a result of years of college education.  I'm playing theremin with serious intentions of performing in the classical setting and am working on arrangements of pieces I used to perform on solo guitar and arranging them for theremin and guitar accompaniment.  I also like improvising, and using a loop pedal to loop in the individual notes in a chord on different pulses seems like a good way to make the time I spend improvising more productive for intonation as I will be improvising over a scale with in tune scale degrees (I can listen for accuracy before looping it)ringing around it.  Basically my point is, see how being pompous gets you nowhere?  

"Get a long audio lead, plug this into the theremin"

Just curious...where would one plug this audio lead into the EWS?

Dear Himtroy ~

Please pardon Thierry's forward words ~ he is a huge defender on how the theremin should be played, what should be played on the theremin etc... But you do what you feel is right and get the most enjoyment of! Heck I play Enya's pieces on it and it makes certain people cringe! Why would I play elevator music on such beautiful and important instrument...? I still do (and I still don't give a rats a$$) and love it :)

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Thanks for the help.  As for the other comments (Thierry)...I've been studying music for a long time and was a pretty high level performing classical guitarist before I hurt my hand.  I have very good relative pitch and a very good understanding of music theory as a result of years of college education.  I'm playing theremin with serious intentions of performing in the classical setting and am working on arrangements of pieces I used to perform on solo guitar and arranging them for theremin and guitar accompaniment.  I also like improvising, and using a loop pedal to loop in the individual notes in a chord on different pulses seems like a good way to make the time I spend improvising more productive for intonation as I will be improvising over a scale with in tune scale degrees (I can listen for accuracy before looping it)ringing around it.  Basically my point is, see how being pompous gets you nowhere?  

"Just curious...where would one plug this audio lead into the EWS?" - bisem

Into the EW's audio output socket! ;-)

Plug the lead into this socket, loop it 'round where the thereminist is standing (the closer the better, and the more wire/loops the better - within reason) then run the wire back to the amplifier...

The cable is carrying audio in its center core, but the shield is grounded - its the grounded shield that cpacitively couples to the player, increasing their ground capacitance.

The (better) alternative is to solder a wire (single, stranded hookup wire or some ultra flexible wire with a lot of fine conduction wires) to the ground (screen) tab on the audio connector plug (which is plugged into the THEREMINS audio output) and run this to anything conductive (foil, conductive mat, long loop of wire)  whatever that is in close proximity to the player .. The other end of the audio lead can then go directly to the amplifier, so neednt be long.

If you dont solder, but have metal plugs, you can wrap the wire round the plug so it makes contact, then tape it in place - or use a large crocodile clip which can grip the plugs metal body, and get a ground connection that way.

Fred.

I have used this wire in the past - it can also be woven into a simple link type door mat easily to make a tough (but a bit uncomfortable to stand on) ground coupling mat - The idea is to get as much ground area close to or under the player as possible, without causing risk of entanglement or discomfort ;-)

I believe that linearity can be greatly impaired if the primary source of player-ground coupling is the theremins body or leads / equipment in the vicinity of the theremin. Ideally, there should be no change in players ground coupling in any position they assume (or pedal / wire they stand on) , and this coupling should be strong - IMO, that is the only way to get consistent reliable sensitivity and linearity with any theremin.

In fact, it wouldnt surprise me if one gets better linearity from a cheap Silicon Chip theremin (which has no linearization circuitry) with a well grounded player, than you would get from an EW (or perhaps even an EW Pro) where the player is coupling to ground only via ground local to the theremin.

Added -> (a bit OT)

I wonder if the design of the E-Pro, with its pitch arm extended away from the theremins body, may be getting some of its linearity improvement because of this design?

As I see it, if the pitch antenna is close to its grounded circuitry, then as the hand approaches the pitch antenna, the hand / arms coupling to this circuitry is more likely to increase - The result will be an increase (if the player is poorly grounded "externally") in players coupling to both the "antenna" and ground simultaneously, so the capacitance will increase more sharply as one approaches the antenna.

By moving the antenna away from the body (and by placing the EQ coils in the arm) the theremins ground is more distant from the antenna....... So as the hand approaches the antenna the proportional coupling to the theremins ground will be reduced, giving a less sharp increase in capacitance, and probably improving linearity - particularly at high audio frequency / close to antenna playing area.

In fact, thinking about the whole physical design of the E-Pro in this light (the above is only a hypothesis though) it makes a lot of sense - A slender body which will probably couple capacitively more with the players body than with their arm / hand, and a sensing electrode (antenna) moved away from the theremins grounded bits... Brilliant!!

Plug the lead into this socket, loop it 'round where the thereminist is standing (the closer the better, and the more wire/loops the better - within reason) then run the wire back to the amplifier...

As some of you know I built a battery powered busking case for my EWS a while back and was having grounding issues.  First I used a metal plate with rubber tread glued on both sides connected to the amplifier ground and played with one foot on the plate.  This worked but after a number of uses the wire connecting the plate to the amp would break and disconnect.  Then I just took a long length of speaker wire connected to the ground screw on the amplifier and wrapped it around my ankle a couple times.  This also worked but on occasion I would forget the wire was attached and try to walk away breaking it off.  Now I just use an 18ft audio cable and and create several loops on the ground approx one foot in diameter in front of my busking case and  put one foot in the middle. It isn't like playing with AC but it definitely gets the job done!