Fred Nachbaurs Theremax modifications

Posted on Feb 6, 2014

The purpose of this page is neither to give a comprehensive review of this popular theremin design, nor to be an introduction to the fascinating and quirky world of theremins in general. If you`re wondering `What the heck is a theremin `, check out the links on the index page. That being said, there are a few comments that bear making before we g

Fred Nachbaurs Theremax modifications
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et on with improving an already excellent design. The "Theremax" is a nice implementation of the classic Theremin idea. It does everything that the more traditional designs do, plus it contains added circuitry (i. e. "frequency- to- voltage converters, " or more simply F-V`s) to convert the pitch and volume signals into "CV" (constant voltage) signals that can be used to control external devices. For this reason its designer has opted to call it a "Gestural Controller. " Theremax handles volume unlike any other design I`ve seen. Rather than using a simple LC circuit that is detuned by hand proximity, it employs a separate oscillator pair with its own frequency-to-voltage converter to effect the volume change. The result is a dynamic range vastly greater than that afforded by previous designs such as the SWTP design informally adopted by TECI (Theremin Enthusiasts Club International). Theremax uses velocity (derivative of volume) to modify the sound by introducing asymmetry (and therefore even-order harmonic distortion) into the VCA. The idea here is to give a feeling of articulation on notes that are played with high velocity, much as a piano sounds different when struck hard than when played softly. The "Timbre fader" was another feature that convinced me to buy, work with, and help promote this fascinating device. This allows a transition between the classic sine-wave sound, and a harder, more penetrating square-wave...

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