My new RCA 1264 replica Theremin...

Posted: 6/13/2012 7:18:04 AM

Joined: 6/13/2012

...was put on front of this great website, many thanks to Jason! A short introduction of myself: I am working as an R&D engineer in Germany for a major sensor company. In my limited spare time I design speakers and mostly "tubed" audio amplifiers - most of them for me and my friends, but some for Vincent and TAC (brands of german company Sintron) and Thorens (Switzerland) too. I started building amps when I was 15 years old - and my very first project was a tube guitar amp based on EL84. I collect antique radios and I am especially interested in uncommon circuitry.

For the High-End market I designed and organized the production of the flagship amps Thorens TEM3200 and TEP3800. Both amps incorparate a patented floating balanced amplifier. I am a regular contributor to the European Triode Festival ETF where I held presentations about old and new analogue circuitry - and most important where one meet the greatest audio and tube community on earth :-). 

The RCA Theremin has attracted may interest for many years because of its genuine circuitry and realisation. The retirement of my colleague was a kind of "culmination point" to jump into the real work and start this rather complex project. There are many details which must be solved (mechanics, circuitry, parts). Especially the dimensions and windings of the coils are critical (and I found different datas about it on the web - which one might be right?). And these coils should look like and behave like the original...

More details later. This week and most of the next week my timetable is overwhelmingly full.

Regards Frank

Posted: 6/13/2012 11:04:26 AM

From: Canada

Joined: 8/1/2008


You have created a beautiful instrument! Your attention to detail is remarkable and I love your plexiglass front that allows us to see the heterodyne "sanctus sanctorum".

I beg you, please get someone other than your one-armed 8-year-old to demonstrate the instrument. I'm sure the boy is very bright and adorable, and I'm sure you're very proud of him, but my Labrador retriever could have given a better demonstration of your theremin!

Your work is very impressive and as the owner of two RCA's I am very interested in hearing what it sounds like in the hands of someone who can actually PLAY. 

I hope none of this sounds too ferocious but let me ask you this. If you had built a piano, would you present it to the world by having someone who knows nothing about music bang on the keyboard?

Posted: 6/13/2012 8:25:16 PM

From: Brooklyn,NY

Joined: 12/1/2009

Frank- excellent work.   Good to see a new generation of RCA's out in the world. - What is the is the 3rd tx on the osc chassis?  - convert the output signal to low impedance speaker? 


FYI...Mark mckeown's coil info is correct.  The # windings and wire dia is for double cloth covered wire, but Ive found that on the small osc coils the difference between cloth-covered and single layer enamel is negligible.  On Art's page, his antenna coil info is correct and would be the way to go if using enamel wire, though #33 single build is very difficult to find in qty under 10lbs) ...  but he is way off on the osc coils.  He uses  completely different size forms and wire than what is found in an RCA, (though they may have the same inductance and function the same in the circuit, havent tried it.)

Posted: 6/14/2012 3:08:05 PM

Joined: 3/30/2012

Great design and build job indeed. Agree with Coalport that a better (i.e. musical) demonstration is sorely needed.


Posted: 6/17/2012 11:22:57 AM

Joined: 6/13/2012

What is the is the 3rd tx on the osc chassis?  - convert the output signal to low impedance speaker? 


Yes, that is the output transformer. I took one from an old "Sachsenwerk" AM radio having an impedance ratio of 7000 Ohm :  6 Ohm. That works well in cooperation with the 1626 which I have used instead of the 71. 

Meanwhile I was able to buy an original RCA 106 speaker, which has the output transformer for the 71. In the coming months I will build the next replica 1264 Theremin using the same coils, chassis etc., but 71 output tube just to compare it with the 1626. I will report about the measured and sonic differences.

@ coalport:

"I beg you, please get someone other than your one-armed 8-year-old to demonstrate the instrument."

First, my son had broken his arm in February and on the video one can see the plaster supporting the recovery. Now he is back in perfect shape - having 2 arms of course.

Second, I built the Theremin as an engineer who is very much interested in music - but I am not a musician. And, my former colleague is an engineer as well. So both of us cannot play the Theremin. You are absolutely right, someone who is able to play a Theremin would be a much better presenter of this device. Unfortunately I don`t know anybody who could do this.

So, please relax, my son tried it out when the Theremin was just ready to play. It`s fun! And you see the enthusiasm. In my opinion it`s great if children are excited about technics and music - in the real world and not only as computer junkies hunting pixels. Trying out the real thing is the best way for learning and excitement!

Of course, I could have wait till I found someone who could really play the Theremin - but that could have took years... Maybe this video attracts attention of someone who lives in the southwest corner of Germany and is able to play a Theremin. I would be happy to get to know him/her.






Posted: 6/18/2012 11:36:17 AM

From: Canada

Joined: 8/1/2008

FB wrote: " son had broken his arm in February and on the video one can see the plaster supporting the recovery.....It`s fun! And you see the enthusiasm. In my opinion it`s great if children are excited about technics and music......"


Hi Frank,

Your video was presumably intended as a demonstration of your instrument, not as an example of the kind of excitement that musical technology can produce in kids.

You have created something wonderful and I think you should contact one of the many fine thereminists who live in Europe. I believe Carolina Eyck is based in Germany and she can be contacted by email through her website. 

It is very important that a luthier collaborate with virtuoso players of the instrument he makes, even if he is a "luthier de l'electronique" like the late Maurice Martenot. 

If you were making violins, I'm sure you would readily admit that having the advice and input of a professional violinist would be important for the refinement of your instruments. For some reason, theremin makers often make the mistake of approaching the building of their instruments as if they were making a radio - a device for which they already possess all the knowledge they need.

In the theremin community there are basically two groups of people: builders ("tekkies") and players (musicians). Among the builders, there are two subgroups: those rare souls, such as yourself, who actually make viable, professional level instruments, and those whose interest is primarily in technical discussion. 

I am currently up to my eyeballs in the creation of a large, ancient Egyptian "Middle Kingdom" style, arched harp (this is a 'C' shaped instrument without the familiar front pillar we see on modern triangular harps. It was the Stratocaster of 1500 B.C.). I am making it without nails, using only the materials available to the luthiers in ancient Egypt. What will happen when tension is applied to the strings?

There is a chance that the instrument will snap in two! 

I mention this because I have encountered a situation similar to the theremin building enigma. People who have undertaken what I am currently doing, cannot play the instruments they have made. They strum and plunk but they don't PLAY. I, on the other hand, can play the harp but don't know diddley-squat about ancient harp building! I am having to learn by trial and error. 

Fortunately, I have both cattle and forests, so I have access to an endless supply of the only two materials involved in the authentic creation of such an instrument: cedar and leather. 

here Bossie......may Hathor forgive me!




Posted: 9/6/2019 7:11:42 PM

From: Hungary

Joined: 9/6/2019

Hi! I see this topic has not been active for a long time, but my arrival will hopefully give it a bit of a kick!
I would also like to share my latest creation, which you can watch videos by clicking the link below.
The language of the videos is my native language, Hungarian, but the pictures speak for themselves!
Have a good time watching the videos!

Edited by thf for better readability

Posted: 9/7/2019 1:06:00 PM

From: Northern NJ, USA

Joined: 2/17/2012

Hi Ecopityu,

I like the way your Theremin lights up a hand held fluorescent tube!  Quite impressive!  Proof positive that you have a high voltage swing at both antennas (and a certain amount of power as well).

Posted: 9/8/2019 4:23:16 PM

From: Berlin Germany

Joined: 4/27/2016

Thank you for sharing the insight in your work! 

Posted: 9/9/2019 7:29:29 AM
Henk Brand

From: Schiedam The Netherlands

Joined: 12/22/2014

Hello Ecopityu,

I really enjoyed watching your videos! Nice work! It reminded me of the good times when I was struggling to built a replica of the Clara Rockmore Theremin. I know it’s a lot of work to get a good working model. Esspecial the volume part was difficult to built because of the lack of information on this part so it was much trial and error to get it right. I put some photo’s in Photoalbums a few years ago, so you can see how I built mine. Anyway its good to see and hear another Tube Theremin! 

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