RCA Theremin Cabinet

Posted: 5/25/2008 4:34:34 PM

From: Wiesbaden, Germany

Joined: 5/22/2008

Firstly, I have to thank all of u for posting me so much information. The links are very good.
I know the theremin of Dr. Hoffmann (now owned by Mr.Pringel). I have seen pictures of it and also the videos on YouTube. It would be nice to build this style of the cabinet. For that I can alter the drawing from the link Thierry posted. Making a “long version” of a short cabinet. ;-)
The cabinet work, I think, I can handle. The (big) work is the “beast” in the cabinet. :-o
So the first step after building the cabinet is to squeeze the PAiA kit Theremax in the cabinet for the time the tube part is in process.
What do you think about that?
Does the PAiA Theremax sound good?

Posted: 5/25/2008 5:15:00 PM

From: Colmar, France

Joined: 12/31/2007

I cannot say if the Theremax sounds good, since I never had one in my hands. But it seems that the original circuit design is not optimal.

Lots of additional information including some "Howtos" in order to improve playability may be found here (http://www.thereminworld.com/theremins.asp?m=2&t=3).
Posted: 5/25/2008 8:04:30 PM

From: Toledo, Ohio United States of America

Joined: 2/22/2006

Welcome to Theremin World!
The Theremax is the best 'true' kit Theremin available. The timbre can be greatly customised. From a silky smooth sine wave to a raspy sawtooth, a heart-felt cello to a angelic woman--- all can be had by implementing modifications to the circuit board. Modification information that is freely available at PAiA, Theremin world and on the web. The PAiA Theremax can also be a CV source, or made to control MIDI instruments and as a controller for MIDI information streams with the MIDI board that PAiA sells.
As to concerns to the linearity of the Theremax,
my experince has been that a larger diameter
pitch rod and volume loop than PAiA suggests is absolutely vital for optimum response.
The very lowest notes can still be troublesome, but the low to mid and upper ranges become quite playable.
Also, a cabinet design that physically seperates
the volume loop and pitch rod by at least eighteen inches seems to make a great improvement in the Theremax linearity.
Just my thoughts...

Good Luck!

Posted: 5/26/2008 10:09:29 AM

From: Richmond Hill, Georgia

Joined: 9/18/2005

If you are going to this much trouble, you absolutely must have reproduction RCA antennas. Mike Buffington has made them in the past and my friend Rudd Long makes them from the drawings Jeff came up with. Jeff may make them too. The originals were nickel plated.

The larger aerials absolutely improve performance.

Check out my webpage http://www.neidlinger.us/keppinger.htm

Posted: 5/26/2008 3:42:14 PM

From: Wiesbaden, Germany

Joined: 5/22/2008

So the antennas of the Thermivox are to smal, or nearly big enough to have a nearly good result.

When I built my one RCA cabinet than the antennas must also in the shape of den original ones.
Posted: 6/3/2008 4:06:55 PM

From: Wiesbaden, Germany

Joined: 5/22/2008

Hallo from Germany

My Theremin project is gradually going on. It’s great fun for me.

At the moment I'm looking for the measurements of a Diamond speaker and replacements of the knobs, switches and the pilot lamp for the RCA cabinet. Is there anyone who can help me with this?
Meanwhile I pretty much decided that I will not build a floor length cabinet because I think that the usual cabinet with the legs looks more elegant.

Today the CD with Clara Rockmore arrived (The Lost Theremin Album). What an artist she was.

Posted: 6/3/2008 6:32:20 PM

From: Brooklyn, New York

Joined: 11/25/2005


I have measurements from Floyd Engels' replica speakers. I have yet to work on my replicas, and updating and organizing the drawings that Floyd sent. I would like to provide digital files and add some drawings that Floyd has only provided sketches of. Also, I might get the chance to see Clara's diamond speaker first hand, which would help immensely. I probably won't get this project done until the end of the year, so if you're patient, I can provide info then.


Mark McKeown has said he has identical RCA front panel knobs. I purchased a set from him a while ago and they were very clean and nice.

The switches are standard ball tipped switches from the day.

I also have measurements of the pilot lamp for inclusion in the RCA drawings. hopefully I can get that out there soon too.

I have given the speaker info to Tim Tate, an Australian theremin player, to help him with a speaker he was going to build. I don't know if he ever got it done or not. Here's what I've told him:

the mahogany base is 20" x 20" x 4 1/8" high with a 10 degree slant, 3/4" thick. A dark finish like the RCAs. thick rubber feet
the speaker is a 12" Jensen 25 watts (unknown what the originals were, Clara's was replaced before Floyd took measurements) You can order them from Antique Electronic Supply in Tempe AZ
It stands 93" tall, total height (Floyd also made it possible to stand 84" for smaller ceilings with different pipes and mount attachments)
the metal frame is 26" square, made of 1" angle steel, welded and milled smooth (Lev's originals were not welded together and became loose over time)
the wood board that is mounted inside is 3/4 ply, with the ~12" hole dead center.
The speaker cloth is a nice dark brown, unsure of any pattern/weave (spray mount the cloth down so it doesn't slap on the low notes)
There is a metal grill over the cloth (Floyd used caning to replicate it).
The pipe is 1" OD, lengths of 35" and 35.5" per side with a coupling 2" long, straight thread.
the pipes insert into standard 1" flanges on the wood base and wing-nut screwed down on top onto a L shaped steel mount.
The edges of the flanges are 5/16" from the center peak. Since the flanges are 4" in diameter, the center point would be 2 5/16" from the center peak of the wooden base.
All metal hardware painted black (likely gloss, not matte)

The theremin speaker is very top heavy. Floyd made some neat additions to run the speaker wire though the pipe to make it look a bit cleaner and safer. Just cut holes in the pipe and watch out for crimping the wire. Floyd's originals had an option for switching for an Etherewave/modern theremin and an RCA., using switches to bypass the transformer. These were mounted on the back of the board.
Posted: 6/7/2008 1:06:15 AM

From: Wiesbaden, Germany

Joined: 5/22/2008

Hello Mike,

thank you for the information which was very helpful to me.
It’s not a problem to me to wait until you have seen the Diamond speaker of Ms. Rockmore. If I’m finished earlier with my Theremin I use my old Grundig vacuum tube radio to listen to that what I’ll produce with the Theremin. ;-)
When Florian, a friend of mine who builds the electric part of my Theremin, is beginning to start with building up the instrument, we need some parts and I then will ask if you can help us with some of these things.

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