The Principle of the Theremin
 

A Commentary by Art Harrison

A musician's proficiency on a specific instrument partly depends on his knowledge of its physical properties,
specifically in terms of how it needs to be adjusted in order to provide adequate response to "actuation."

For a vast majority of instruments that operate on the conventional principles of actuation, that is, being blown
into, plucked, or struck, milenia of experience has provided a set of rules that allow our ability to create music
with them a well-established art. Methods for virtually every orchestral instrument abound and are easily
accessible to the student.

With the emergence of the class called "electrophones" in the early 20th century, instruments such as the
theremin appeared which starkly departed from the conventional playing methods that apply to the
millenia-old ones that are part and parcel to human experience. Suddenly, the concept of physically
touching instruments in order to play them was dismissed, replaced with the concept that gestures near
them would be used for the method, instead. Now, the quality of performance and the complex rules of
musician-to-instrument interaction no longer specifically depended on such things as the physical adjustment
of strings, mechanical valves, levers, and pistons, but necessarily included more-abstract (and invisible)
attributes such as the capacitance between the musician and instrument.

An insurmountable edict of nature proves that the relationship of the response of an instrument to physical
actuation includes a plethora of non-linear effects. For example, the criticality of an adjustment of the bridge
on a guitar or the position of a reed in a saxophone must be rather exact in order for the instrument to
respond effectively to actuation. While the parameters of adjustment may seem non-critical to the uninitiated,
the actual criticality of these parameters are daunting. That is why there are subject matter experts who
specialize, for example, in "setting up" a guitar, or tuning a piano.

The adjustments of parts on a conventional instrument are facilitated by the physical appearance of things
such as bridges, valves, frets, and reeds. For example, it is relatively easy to see when a fret is worn or a
tuning peg is loose. However this may not be the case for instruments such as the theremin, where the
cause of a malfunction may be due to something completely invisible, such as an interfering electrical field
from a lighting fixture or cell phone. More subtle causes of malfunction may be caused by other non-obvious
conditions such as a poor electrical connection to earth's ground, the length of a connecting wire, the lack
of electrical shielding, the slight motion of an output cord on a breezy day, the proximity of surrounding
objects or, for many instruments, the ambient temperature.

All these factors make the practical use of theremins relatively difficult. In order to use them with good effect,
the player virtually has to be both a musician and an electrical engineer with specific knowledge of its design
principles, or at least have ready such expertise when there are problems.

All these factors are contributors to the fact that even after more than a century, there are very few musicians
who play the theremin. This is because making one work, especially in an environment where myriad undefined
electrical conditions may exist (such as at a performance venue) is often a difficult task.

Arthur Harrison
CEO, Harrison Instruments, Inc.
March 6, 2022
©2022 Arthur Harrison

Website Contents

Title	Published	Notes
THE 2006 "MINIMUM THEREMIN"	09-06-2006	An Improved Version of the Minimum Theremin
THE "126 THEREMIN"	08-23-2002	A Complete Vacuum Tube Theremin
THE "125 THEREMIN"	07-13-2002	A Vacuum Tube Pitch Theremin
THE "203 THEREMIN"	09-22-2001	A Battery-Operated Version of the Wien-Bridge Theremin
THE "145 THEREMIN"	11-19-2000	An Improved Version of the 144 Theremin
"THE WIEN BRIDGE THEREMIN"	10-16-1999	A Theremin without Inductors
THE "MINIMUM THEREMIN"	05-17-1999	A Very Simple Pitch Theremin
THE "144 THEREMIN"	09-18-1998	An Improved Version of the Southwest Technical Products Model 142 Theremin

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