B3 Problems

Posted: 4/12/2014 1:54:43 PM

Joined: 4/12/2014

Hi to all, I'm sorry to come here before introduce too much, I'll do as soon as I can.

I'm Michiyo, 39 years old and I'm a japanese women living in Italy (sorry for my bad english, it's really not a well known language).

I recently bought a B3 theremin and I have a problem I can't understand. 

I made change the power supply (to american 110 v to italian 220 v) and set the output on 12v, but the sound is terrible, like a radio noise and no others sound. I can't understand why... 

It's only a problem of the power supply? It's a problem of the theremin self? May I sand back to the sellers and ask them to change? 

I really don't know, so I will be very grateful if you could help me... 

Thank you so much. 

Posted: 4/12/2014 4:54:44 PM

From: Colmar, France

Joined: 12/31/2007

Hi Michiyo,

what you describe is most probably not a problem of the theremin itself. There are other possible causes for what you see:

a) Wrong power supply: there are basically two types of power supply on the market, the ones with linear regulation and the ones with switched mode regulation. You will have to use one with linear regulation! The switched mode types are smaller and cheaper (and consume less power for themselves) but there is a high risk of RF interference with whatever theremin.

b) Light bulbs in proximity: The "ecologic" ones (which are now so "famous" in Europe) have also a switched mode power supply in their socket which can also interfere with the theremin.

c) Grounding problems: The theremin as a capacitance-sensitive RF device has to be electrically connected to ground/earth. This is normally done through the amplifier. Always connect your theremin with a shielded audio cable to the amplifier and use an amplifier which is well grounded, that means which has a three-prong wall plug.

If you are not sure about the nature of your actual power supply and about the correct operation of your theremin, you may send the whole stuff to me in France for a free diagnose/checkup. You may contact me by email service(at)theremin(punto)tf

Posted: 4/12/2014 5:22:56 PM

Joined: 4/12/2014

Thank you so much Thierry!!! 

I tried with your advices about light and ground and it not works.. but yes, the power supply is the multi one, so on monday I'll change another time ^^ 

I'm sorry to bother you again but I have to put 12 or 24 volt in out? 

Thank you very very much for all the advices and your time, of course you'll be the first to know how it works on monday! 


Posted: 4/12/2014 6:45:45 PM

From: Colmar, France

Joined: 12/31/2007

You need a power supply which has an internal linear voltage regulation (not switched mode), an output voltage between 12V and 15V and can deliver between 100mA and 500mA.

The "switched mode" does NOT mean that it can't have a voltage selector switch, that is a misunderstanding!

"Switched mode" (alimentatore a commutazione o sincronizzato) describes the internal principle of operation of the power supply (you can't see from outside what it is, you need a competent technician to see the difference), as opposed to linear voltage regulation (alimentatore lineare stabilizzato) which is another (less energy effective but the only way for Theremins) principle of operation.

Posted: 4/13/2014 5:48:41 AM

Joined: 3/30/2012

Welcome Michiyo. Your English is quite understandable, so don't worry about that.

Posted: 4/13/2014 3:17:51 PM

Joined: 4/12/2014

Thank you again to all! 

Thierry, I really don't know anything about electronics so it's easy for me make such kind of mistake... Thank you for the explanation, I'm really excited about studying theremin so I would like it be monday!


Posted: 4/13/2014 5:19:46 PM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

Hello Everyone and lovely Michiyo,

I am sure yours is not the only B3 in Europe, anyone what is a product LINK of what is being used for power?

Thierry would something like this device work with the original Moog wallwart "with ground" or the B3 plugged into it?

Obtaining earth ground from the power amp works but not always practical.

Keep up the fine work and research.


PS: Michiyo have you heard the interesting theremin-dan-bau method?

Theremin meets the dan bau .mp3  500kb   This method arrived 4-13-14

Posted: 5/6/2014 9:37:12 AM

Joined: 5/5/2014

"You need a power supply which has an internal linear voltage regulation (not switched mode), an output voltage between 12V and 15V and can deliver between 100mA and 500mA."

Any idea of power supply models that fit this criteria? Searching the internet does not yield many viable options.

Posted: 5/6/2014 10:22:58 AM

From: Colmar, France

Joined: 12/31/2007

This one responds exactly to the needed specifications for all B3 (also DeLuxe and Pro versions) Theremins:

Italy : http://it.rs-online.com/web/p/alimentatori-plug-in/4846052/

France : http://fr.rs-online.com/web/p/alimentations-enfichables/4846052/

Germany : http://de.rs-online.com/web/p/steckernetzteile/4846052/


Posted: 5/8/2014 8:13:41 AM

Joined: 5/5/2014

Thanks Thierry.

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