Shopping Suggestions Wanted

Posted: 8/2/2009 12:38:56 AM

Joined: 7/30/2009

Well, I think what they meant was as far as what I want out of the tone. The B3 seems to have a very distinct sound, interesting but not quite what I'm after, and seemed to think I wouldn't be satisfied. The thought on their end was that there is greater tonal control on the Etherwave, as the B3 only has pitch and volume adjustment knobs.
Posted: 8/2/2009 12:39:00 AM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as . ...................................

Joined: 12/7/2007

[i]"My diligent electronic savvy friend discovered that moving the board around had loosened a few of the solder points on the power connector. He thinks after the five years I've owned it this may be normal wear."[/i]

No - it is not the result of "normal wear" .. Well soldered joints will last indefinately - the fact that moving the board caused failure makes me think that the problem with your sound is likely to be a fault caused by poor quality soldering.. probably on the board somewhere..

Also, I assure you, there is absolutely no risk in connecting a capacitor across c23.. However, this capacitor must be connected directly to the board, you CANNOT go using clip leads on Theremins - there are lots of high frequency signals flying about, and results when using any lengths of wire to connect components are unpredictable.

C23 is not in a critical part of the circuit - it would be quite difficult to do anything here that could damage your Theremin..

Also, I have just seen that the point connecting to C23 is also connected to pin 7 of the Aux connector .. Wish I had noticed this before.. All you need to do is connect the capacitor between pins 7 and pin 1 of this connector (this connector is shown on Fig 4, at the top of the page, right hand side, above C4.. it is labeled (left to right).. AUX,AUDIO,+12V,-12V,AMP OUT,AMP IN,VCA OUT,GND .. You want to connect the capacitor between AUDIO and GND.

BUT - There is no point in polishing a turd.. I think it highly likely your Theremin has a fault - It might be a good idea to get a Moog engineer or someone who REALLY knows what they are talking about regarding electronics, to look at your Theremin.

Also - could you please edit your update posting (8/1/2009 9:48:55 PM), and state there that it was not my recomendation which caused total failure of your Theremin.. I do not really want someone at a later time to find this erroneous posting while doing a search, and think that my advice blows up Theremins! ;-)

Thank you TT, for your vote of confidence!
Posted: 8/2/2009 12:50:31 AM

Joined: 7/30/2009

(*note* he explained why he thought it normal wear, my Etherwave is one of the wooden cased ones, so the power connector isn't supported by the case and is only secured by it's solder points. I travel a lot and so there is a lot of pluging/unpluging going on. So, every time I plug in I'm pushing on the solder points, and every time I unplug I pull on them. Seems logical to me, but I'm an idiot.)

Ok, so, I got my Etherwave back and it's funtioning as normal now. It's been great for five years, and frankly, is past warranty anyway. As far as this particular one sounding different, I've not noticed that, sounds just like all the other Etherwaves I've heard. But onward.

The 47nF capacitor is now soldered to the bottom of the board. And yes, there is a difference in sound now. What it now sounds like is basically the same as it sounded before when the waveform knob was turn all the way counterclockwise, when turned the other way, before this increased the "buzzy-ness" of the sound, but now it seems to remain nearly unchanged.

Perhaps I should try adding another capacitor where you mentioned on the Aux connector?

I should at least start a new discussion for the mod I think.
Posted: 8/2/2009 12:58:08 AM

From: Colmar, France

Joined: 12/31/2007

There is a small but well equipped theremin repair shop in north-eastern France. The owner states that there are no more secrets for him inside the Etherwave Standard. His own has almost seven almost linear octaves and a very wide spectrum of different sounds... ;-)

You may send yours in for a complete verification, eventual repair and fine tuning.

Shipping to Europe is not a problem because you would only have to send the "nude" box without antennas and power supply and write "defective item for repair" on the customs declaration.

Just contact him by email theremin(at)tfrenkel(dot)com. His first name is Thierry and he speaks mainly French and German, but also a little English and Hebrew.

BTW: The waveform of the old theremins such as Clara's starts really with a sine wave, but is distorted on the quadratic characteristic line of the mixer tube which makes it sound rather like a sawtooth wave. This effect is partially compensated by the rigid low-pass filtering of contemporary recording technique. It is nearly impossible to emulate these effects with modern transistor based circuits.
Posted: 8/2/2009 1:08:55 AM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as . ...................................

Joined: 12/7/2007

[i]"Perhaps I should try adding another capacitor where you mentioned on the Aux connector?[/i]

Yes.. If the sound is moving in the direction you want, keep adding capacitance until you get closest to the sound you want, or you get no sound at all..

Also, remember to test the sound over the full playing range.. High frequencies will be attenuated to a greater extent, so youi need to get a balance between the sound you want at the low end, and the attenuation you are willing to accept at the high end.

You may not be able to achieve this 'balance' - it is an extremely crude and simple mod.. The sound you will get would not be at all to my taste! ;-)

Find the capacitance which gets closest to what you want.. if this is what you want, fine, problem solved.. Otherwise your total capacitance values will give me a clue about the sound you are after.. I MAY then be able to work out a slightly more complex modification which gives you more of what you want..

IF I undertook that, and IF you got the sound you want, I would ask you to think about making a donation to ( for what the fix has been worth to you.
Posted: 8/2/2009 1:14:49 AM

From: Asheville, NC

Joined: 1/25/2008

"The B3 can considered as "step down" because..."

Thank you. That is just the info I was wondering about.

Frankly, I'm a fan of the fact that it has no tone control knobs, as long as the tone is good. Which it seems to be as best as I can judge by youtube posts and such (hard to say live, though).

I would not mind a smaller pitch range but a drop in linearity could be bad. As would a greater susceptibility to interference, plus those weak antennea :(

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