Brand new Etherwave Standard + ESPE01 - I hear two tones simultaneously in a specific tone range

[Edited to add : As I have no sound acquisition equipment/software, I edited my post to give a better understanding of the "ghost tone" I can hear]

Hi everyone,

I hope I am posting this question at the right place. If not, please let me know.

I am a brand new theremin learner with zero previous experience in electronic music (musician though). I received my brand new Etherwave Standard + ESPE01 module this week, and have just tested it tonight (got the flu, couldn't do it earlier).

My problem is the following :

I hear an "extra" (deeper) tone when I play tones across the 4th and 5th octaves (the 1st octave being the one closest to the pitch antenna). More precisely, between the 4th F and the 5th A. [Edited to say : I mistakenly numbered the octaves backwards, not knowing octaves were conventionally numbered from the lower to the higher registers. However, this is pure convention and the problem remains]

[Edited to add : I can hear the "extra" tone following the progression of the tones I'm playing. It is not a constant pitch tone. It really confuses me, as I am trying to constantly correct my pitch. I hear the "extra" tone so clearly I can sing it. It is truly a handicap, as I cannot exercise in this specific range.]

I made a schema/picture of the problem, but it seems I couldn't upload it in this message, so it is now my avatar. Please have a look if you feel so inclined. [Edited to say : the schema is below]

My extra problem is the following : I am a total newbie, so I don't trust myself not to make a really stupid mistake. So before I contact the nice person who built my theremin (Thank you Wilco !!!) I wanted to hear your suggestions.
I wanted to had : I hear the "extra" tone whether I'm using headphones or my studio speaker (Yamaha MSP-5) [Edited to say : Both headphone amplifier and studio speaker work on ungrounded power supply. So I am unable at this time to test the theremin with a grounded sound output equipment :(]. I also checked all connectors, and it seems fine.

I really want to believe it is something stupid, like a faulty jack cable.

Dear experienced/knowledgeable people : what do you think ?

Please help !

Thank you,

Emmanuelle

You should post a sound byte, as they say a picture is worth a thousand words. Using audio spectrum analysis may reveal something.

Christopher

Emmanuelle

either you incorrectly call the octave numbers (1st should be bass), or your instrument is incorrectly tuned (on reverse beat zone).

to insert pix go to Media->Photo albums->Add album.

"You should post a sound byte, as they say a picture is worth a thousand words. Using audio spectrum analysis may reveal something. Christopher"

 oldtemecula - Thank you for your message. I have no equipment for sound acquisition, so I'm unable to do this at this stage. Would you have suggestions on where the problem might come from, despite this ? Thank you. E.

In 90% of cases, theremins produce ghost tones when they aren’t properly grounded. The Etherwave theremins come with an ungrounded power supply to prevent double grounding since that might induce other problems. Thus, it is crucial to connect your Etherwave to an instrument amplifier which is well grounded by using a three-prong mains cable. The ground link between both is then done via the shielding of the Audio cable.

Many beginners make the error to use a small computer speaker or a cheap hifi system. Both don’t provide sufficient grounding. 

Another important source of problems might be external - stray fields of switched mode power supplies as you find them in laptop and cell phone chargers, or even in the sockets of so called eco light bulbs, which interfere with the theremin’s oscillators, leading to ghost tones and distortion, too. Try to unplug or switch off everything which is not needed and try again.

"Emmanuelle either you incorrectly call the octave numbers (1st should be bass), or your instrument is incorrectly tuned (on reverse beat zone)."

ILYA - Thank you for your message and tip re. photo insertion. I didn't know there was a correct numbering of octaves, so I mistakenly numbered them in the reverse way for explanation purposes.

Wilco built my theremin and I have full confidence in his work. However, because I have no technical knowledge, I am stumped by this problem and dreading the possibility the theremin might have been damaged during shipping (though NL to DE isn't such a long way).

Can you think of what might cause this issue ? Thank you. E.

"In 90% of cases, theremins produce ghost tones when they aren’t properly grounded. The Etherwave theremins come with an ungrounded power supply to prevent double grounding since that might induce other problems. Thus, it is crucial to connect your Etherwave to an instrument amplifier which is well grounded by using a three-prong mains cable. The ground link between both is then done via the shielding of the Audio cable. Many beginners make the error to use a small computer speaker or a cheap hifi system. Both don’t provide sufficient grounding.  Another important source of problems might be external - stray fields of switched mode power supplies as you find them in laptop and cell phone chargers, or even in the sockets of so called eco light bulbs, which interfere with the theremin’s oscillators, leading to ghost tones and distortion, too. Try to unplug or switch off everything which is not needed and try again."

Dear Thierry, thank you for your answer ! I appreciate it very much.

Concerning the grounding : I'm using a Yamaha MSP-5 studio speaker on Carolina's recommendation. But you're right, this speaker isn't grounded. In addition to this, my headphones are plugged into an amplifier (Nowsonic Ampix) which is itself un-grounded. So I find myself unable to test the theremin's sound from a grounded sound output !!

I am still within the free-return period for the studio speaker. I am based in Berlin, Germany. Is there a grounded speaker you and the community can recommend in this price range (~300 euros) ? Same question with the headphone amplifier ? (I now wish I had asked Wilco to build an Etherwave Plus, as this comes with a built in headphone output)

I have another question : how do I know the audio cable is properly shielded ? I'm using at the moment a 3m Klotz LaGrange cable.

Concerning the clearing of the field : we're 3 people in 65m² here, so space comes at a premium :) I was careful to keep a ca. 1.5m radius zone free around the theremin (though the speaker, headphone amplifier and their associated power supplies were, I think, within the zone ...). Generally speaking, should I keep *everything* out of the field ? (i.e. just the theremin, me and my seat - no other equipment) and what's the approximate radius the field should have ? (I understand this may vary)

Thank you ! Emmanuelle

Most audio cables are well shielded. This is normally never a problem. 

The Etherwave Plus won’t solve any of your problems. The integrated headphone output gives a totally crappy sound, and you’ll have the grounding problem again when playing only on headphones, besides the headphone cable moving around in your field. Playing a Theremin on headphones is basically a No-No.

The latter has “cybernetic” reasons. When training your hands, muscles, nerves and ears to play on headphones, there is (because the headphones are very close to your ears) almost no delay between your action and what you hear. If you switch then over to a speaker which is only 1m from your ears, there is an additional delay (sound moves by about 330m/s) of about 3ms to which your brain is not trained. Thus, during a new learning period for your brain/nerves/muscles of about 21 days, you will suffer from pitch accidents and smearing between the notes. When you switch then back to headphones, you’ll fall back again and need a new training phase again...

I used the Yamaha MSP-3 and -5 successfully for quite a while with other, better grounded theremins like the tVox Tour or the Etherwave Pro. Playing an Etherwave Standard or Plus through it is only possible when running the theremin’s output through a grounded mixing table before routing the signal to the MSP-5.

A well suited and grounded amplifier for beginners and advanced players is the Behringer KT-450FX. At a price around 170€, you even get optionally 99 built-in digital effects like reverb, delay, etc. like it or not - use it or not. And in case you really can’t do without, it has a headphones output, too. When using it, you should at least make sure that the cable is never in front of you in the field when playing, but rather behind your back.

"Most audio cables are well shielded. This is normally never a problem.  The Etherwave Plus won’t solve any of your problems. The integrated headphone output gives a totally crappy sound, and you’ll have the grounding problem again when playing only on headphones, besides the headphone cable moving around in your field."

Thank you for putting my mind at rest on this.

"Playing a Theremin on headphones is basically a No-No. The latter has “cybernetic” reasons. When training your hands, muscles, nerves and ears to play on headphones, there is (because the headphones are very close to your ears) almost no delay between your action and what you hear. If you switch then over to a speaker which is only 1m from your ears, there is an additional delay (sound moves by about 330m/s) of about 3ms to which your brain is not trained. Thus, during a new learning period for your brain/nerves/muscles of about 21 days, you will suffer from pitch accidents and smearing between the notes. When you switch then back to headphones, you’ll fall back again and need a new training phase again..."

I appreciate what you're saying, and will take it into account in the future.

"I used the Yamaha MSP-3 and -5 successfully for quite a while with other, better grounded theremins like the tVox Tour or the Etherwave Pro. Playing an Etherwave Standard or Plus through it is only possible when running the theremin’s output through a grounded mixing table before routing the signal to the MSP-5. A well suited and grounded amplifier for beginners and advanced players is the Behringer KT-450FX. At a price around 170€, you even get optionally 99 built-in digital effects like reverb, delay, etc. like it or not - use it or not. And in case you really can’t do without, it has a headphones output, too. When using it, you should at least make sure that the cable is never in front of you in the field when playing, but rather behind your back."

Thank you very much for your explanation. These issues are slowly getting clearer in my mind. I also appreciate your suggestion re. the Behringer KT-450FX amplifier.

I would like to ask one more question :
I use one grounded power strip to plug the various equipment (theremin, studio speaker, headphone amplifier). Is it OK to do this ? Are there some particular considerations I should pay attention to ? What is the best practice in this matter ?

Thank you again for your very practical help, Thierry. It is very much appreciated.

Emmanuelle