Theremax Antennae Question - Will Collapsible/Telescopic work? Ideal length?

Posted: 6/9/2007 8:29:44 PM

Joined: 6/9/2007

I am just about to build the Theremax and I, too, am a noob and wanted to ask this:

1) is there any documentation for ideal length of the pitch/volume antennae? (I'm sure this depends, to an extent, on the material used)


2) I was thinking of using the collapsible/telescopic antenna like the kind you may find on radios, TV, cellphones, etc. These are easy to locate via Radio Shack, etc. and would allow me to make an antennae mount for removable antennae (allowing me to streamline the case -- an Atari 2600 -- for movement and transport) Does anybody know if these will work? I presume it probably would, but that is also why I'm wondering about ideal length...

3) An even better solution would be if somebody knows how I can build or find a telescopic antenna with a 1/4" phone plug, like this one:
which is on the HORST website:

This would allow me to start building the Theremax and use a standard 1/4" jack interface for the antennae (I would still go vertical right-side for pitch, horizontal left for volume)
Posted: 6/27/2007 3:13:01 PM

Joined: 2/21/2005

The length of the antenna will chiefly affect the size of the space-control area; short antennas will produce a small, compressed control space, while longer antennas will produce a larger control space, with less compression towards the upper register of the instrument.

I have seen many models of homebuilt theremins using a telescoping radio/tv antenna for pitch control, and I have experimented with one of my own, and in my opinion, given the typical design of the pitch circuit in most theremins, coupled with the basic physical needs of most adult players, the best length of antenna is about 15 inches; this has nothing whatsoever to do with technical requirements, this simply produces the best, most user-friendly control space for the serious solo or concertizing player.

I abandoned the antenna, finding it ultimately flimsy and non-professional in appearance. The commonest style of traditional antenna for pitch is a simple rigid rod of any conductive metal, held to the cabinet using plumber's compression fittings. electrical connections may be clamped, or brazed (welded) to the fittings on the inside of the cabinet.

I have also seen telescoping antennas used for volume control, but I have no idea how they perform. Traditionally the volume antenna is shaped into a loop, simply to put the maximum area of the antenna under the player's palm; this arrangement typically gives the best control over volume.

Past designs of theremins have also used simple metal plates as both pitch and volume controls; early Moog theremins used a plate inside the cabinet itself for the volume control, effectively eliminating that device as an exterior protuberance. Other instrument designs have typically arranged the plates parallel to each other, producing an 'up-down' playing style for both hands; there are somewhat technical and perhaps nit-picky pros and cons to this design, but everyone I know with a plate-theremin seems to be happy with it. Enuff said about that.

The real issue is WHY one NEEDS telescoping antennas on their theremins. Certainly I, as a performer, would admit that the ability to merely telescope one's antennas down to a portable state might be more desireable than getting out a wrench to loosen at least three compression joints in order to disassemble one's instrument at the end of a session (or 'gig' if you like... I don't), and performing the same action in reverse to reassemble the instrument for the next session.

For persons requiring extreme portability with their instruments, telescoping antennas are a legitimate design consideration; however, the nature of the antennas may force the player to develop non-traditional playing styles. A valid consideration for extreme portable theremin designs is: the larger the antennas, the larger the control spaces; if there is too much overlap between these electrical fields (if the antennas are too close together relative to their lengths/sizes) the player will encounter many undesireable effects of interference and electrical resonance, not to mention bursts of news from the local sports radio stations.

As long as we are still exploring the concept of 'ideal' in theremin designs, consider this: the typical human forearm is about 15 inches long. The distance between two average human shoulders is about 15 inches. Humans typically like to keep their wrists at least 15 inches away from each other when they stick their arms out in front of them. 15, 15, 15... get the picture?

My theremin is only 11 inches wide, and I honestly think I pushed the size envelope too far inwards. My antennas, however, stick out on either side such that my two arms with their highly-opinionated wrists are rarely less than (you guessed it) 15 inches apart. I use 30 inches of solid brass rod to form my volume loop, 24 inches of which go under my palm. The resultant antenna sticks out horizontally to a distance of about 11 inches, which makes the entire instr
Posted: 6/27/2007 9:15:44 PM

From: Napa, CA

Joined: 6/9/2007

Thank you... what a great and thorough response.

Well, I noticed the PAiA-supplied copper antennae are far too flimsy, which means transport will eventually lead to bent and warped antennae.

I do comprehend what you are saying about length (one concern I do have with telescoping antennae is that the length could easily change, throwing off the tuning or pickup range -- I plan to set a mark to make sure I extend the same distance each time) I also can see how they could easily bend or break once mounted.

The thing is that I have built the Theremax into an Atari case and, as such, it is rather more of a pain to open and tweak. I can live the case gently and carefully in order to access the coils, but completely removing it is not an option and getting to a suitable area internally for mounting antennae would be a bit of a challenge to do on a regular basis -- so I would need to have the antennae permanently mounted in.

Your response has reassured me enough that I am going to use telescoping antennae (with female 6-32 thread so I can easily unscrew from a mounting bolt ont he case) for pitch and volume for now... although it may not be ideal and I may later modify to have permanently-mounted solid rod antennae.
Posted: 7/4/2007 3:27:19 AM

From: Toledo, Ohio United States of America

Joined: 2/22/2006

You could always find another case, cabinet tank, etc... for your T-max. Don't be married to what seems 'cool', become engaged to that which 'works'.
Good Luck!

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