The theremin, a musical Instrument connected to the birth of electronics. . .

Tube/Valve Altermen Theremin

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The Vision of 2003 . . ."True beauty is hidden in Simplicity"

Clara Rockmore is the #1 theremin virtuosa, but how did Lev Sergeyevich
 create her "authentic" golden sound?  

9.28.14   My 12 year theremin journey seems to be winding down. As time passes I begin to forget details about my build. People seem to gravitate more toward the digital build today which seems to me to miss what the theremin represents... a connection with the past. The most important aspect for me is that authentic sound... not a nine octave whistle buried in reverb.

The Altermen Authentic.wav  2 megs  This is theremin direct to sound card, no acoustic development.

My tube/valve pitch method is not available in general now, but if you are a builder in So. California I would make an exception. After helping hundreds of University Students get a top grade over the years I found my efforts were easily forgotten. No Thereminist developed from it.

My hybrid pitch side uses two of these osc boards and the Phoenix pre-amp section to get the golden sound.

My last project was to breadboard a hybrid Tube/Valve pitch oscillator and see if "Perfect Linearity" could be found. This would clarify if the phenomenon of LINKS and the Lev Antenna was unique to transistor oscillators or could it also be demonstrated using a tube/valve oscillator. 

The answer is Yes!  "Perfect Linearity" is possible with vacuum tubes!

Most of my theremin experiments over the years used Hartley Oscillators operating between 800 kHz and 1000 kHz. This higher frequency allows the design of the Lev Antenna to be more practical. I found that using hand wound air coils in the oscillators was a poor choice because it limited Perfect Linearity to just over three linear octaves and added to pitch drift. My original RS Illusion transistor theremin revealed that using High Q ferrite coils would give more than five linear octaves over the same air core coil setup.. 

A pitch oscillator between 875 kHz and 925 kHz Lev Antenna excitement!

This five plus octave range was also found in my scratch built tube/valve hybrid theremin which also uses ferrite inductors. Using tubes for the pitch and fixed oscillators has a much more subtle Null break point and a better symmetrical wave shape in the lowest notes of the audio sound, compared to transistors.

With my musical crudeness in a 18" pitch field in the sample below I will make a one octave jump by closing my fingers then rapidly opening my fingers within 1" of the pitch antenna. I will repeat this while moving midway back in the pitch field and then near the lowest octave. Each time the same hand/finger movement is used. This is one of the easiest methods of validating any theremins pitch field linearity. I am watching a frequency counter.

Linearity Test.mp3 (200k)
Raw vacuum tube sine wave  
A linear 2400 hz down to 100 hz

Perfect linearity remains no matter what size intervals or octave widths you enjoy playing. This Lev Antenna phenomena once set does not need retuning. It's tuning bandwidth is broad and stable.

My scratch built hybrid theremin uses one vacuum tube for the pitch oscillator, one tube for the fixed oscillator. This hybrid theremin pitch field has Perfect Pitch Linearity and cost less than $200 to build plus seven years of learning the simplicity of how theremins work. My design does not need variable capacitors or exotic variable inductors. It uses simple solid state tuning I designed, the tuning knob can be twenty feet away.

Sound of My Hybrid  mp3
Sine Wave  (188k)
<=Timbre Knob=>
Adjustment direct line-out
Finding The Voice mp3 (470k) 
Authentic No Processing!  
If you would enjoy building this harmonically rich theremin voice with its perfectly linear pitch field, then I have organized it as a "build it yourself" project for about $200 usd in parts. This cost includes dual tube/valve pitch oscillators and a stand alone hand proximity RF volume control board with an adjustable 10" down to 2" shading window. It begins by building the Phoenix design then it evolves from there.

Most of the parts you purchase from Mouser. 

At no cost make your own pc boards from my PDF's. In the future I will have commercially silkscreened and drilled printed circuit boards, this will add to the overall cost. Five Boards = 4 - 3"x 6" and 1- 3"x 3".

This Altermen could become one of the most treasured designs,
 it dispels 13 common design myths.

The tube/valve build begins with the Phoenix Solid State,  then add two tube osc boards.

This horizontal pitch antenna called "The Abbot" is more natural in playing but you could use the vertical Lev
It is played below your shoulders with the normal forward downward arm movement with aerial fingering.
It makes better use of perfect pitch field linearity by changing the angle of play.

The Altermen is basically two Oscillator PC boards & Pre-Amp board mounted on a Mic stand

On the right side of these two 922 kHz osc boards you can see the small IF transformer coils used! The entire hybrid pitch section is made from these three 3" x 6.5" pc boards . Power for everything including the independent volume control comes from the two pcb mounted osc board transformers. 

I posted a list of 13 theremin design myths to TW once but the engineers got too upset for me to post it again. The forum host needed to delete what I suggested, it did not support the engineer models? In theremin design you must allow the theremin to guide you as she will show you most often what does not work and that most methods have an un-musical sound. Modeling relies too much on GIGO which does not encompass all the circuit influences found in analog oscillator design. That is why engineers and their models rarely if ever post any sound bytes. They insist modeling saves time. o-;  

Theremin engineers spend most of their time trying to overcome the negative issues they create for themselves. She (theremin) has attitude and if you're not invited she will make you suffer.


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