Vacuum Tube Theremin

12.01.14

Tube Warmth Altermen

A Single Tube/Valve Hybrid Theremin

Blending the Phoenix with Dragonfly = TW Altermen

In all my years of studying the Theremin I had always hoped to find someone that would contribute to my approach. Well that rarely happens for good reason but I am now at the point that someone might create a simpler volume control that people could use who did not want to use my stand alone version. The engineers I seem to come across just spend years modeling everything and never demonstrate anything that works in reality, no practical hands on experience. It's a wonder they are employed? For a starter approach view the Volume Control of the Melodia or the SWTP solid state designs. My design does have an extra 800 kHz buffered fixed oscillator on board that can be used for Volume, just need an add-on circuit board or PDF with the sensing components laid out. I have an excellent Volume Control, the idea is to simplify this area.

Clara Rockmore's sound demonstrates the vacuum tube phenomena and using a single tube/valve can get there!

The above RCA graphic wave shape is from master builder Andrew Baron's RCA Registry webpage.
Read what he states creates a beautiful sound.

To the left is my audio wave shape of about 440 hz taken from the Altermen line level output.

Notice how similar to Andrew Baron's RCA wave shape. The top flattened part of the wave I call the skew and this is adjustable. It creates the brightness & changing timbre.

The bottom of the sine wave is broad and this is what creates the second harmonic for a fuller or fat sound.

I believe the above RCA graphic wave bottom is clipped and this gives the RCA theremin the buzzy sound on the low end. My osc design uses a pentode, how would you get it to clip the bottom of the wave form? My first guess is to increase the grid negative bias by increasing the cathode resistor.

Next is my RF blend sampled at the positive side of the single D2 detector diode using a 10:1 probe.

Amplitude Modulation, one engineer at TW would get upset when I mentioned RF because he could not grasp that RF has a place in theremin design. It did not fit into his fantasy models causing him anxiety.

This sound byte is raw, no reverb, the theremin out is direct to sound card. This has character, more than a plain digital whistle buried in reverb which you can get from a keyboard. Unfortunately there is a movement for profit to make people forget that the old authentic theremins were able to sound like something unusually beautiful. Hopefully your interest in theremins is more reflective of the dream of Lev Sergeyevich Termen.

Tube-Warmth Passion.wav 2 meg My Ladies Voice wav 1.8 meg

First sample using the single tube method, surprisingly this approach came
to mind just a month ago. The beginning of Nov 2014. It has promise.

When this design is optimized I think it could be built for about 100 euro's or $150 usd.
Anyone building for profit, this design is original, has novelty and works excellent. You have my blessing.

* Perfect Pitch Field Linearity - Drift Resistant - The Voice *
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"The Vision of November 2003 invited Christopher on this journey, it is almost time for him to rest."