Conclusions
During the course of this article, I have compared a theremin constructor with an acoustic instrument. This comparison is not as far fetched as it may seem at first.
Starting from an original design, the maker of a stringed instrument must take the greatest care in choosing what woods to use, how to cut them, how to assemble them using the right glues; and then he has to mount the most suitable mechanical parts in such a way as to balance the considerable play of stresses produced by the tightened strings. The result must be an instrument that sounds good and whose starting characteristics do not change too much over time.
Starting from a good initial diagram, a theremin builder must also select the most suitable electronic components, assemble the circuits in such a way that the radio frequency oscillators do not reciprocally disturb the way in which it works, and wind large coils and position them correctly. It is not unusual that having tried the instrument, he decides to adjust the circuitry in order to increase or diminish the connection phenomenon of the mixer, or to vary the working frequency of the oscillators. All radio frequency circuits have some intrinsically critical points and so it is essential that these are taken into account by the builder when arranging the electronic components, as well as in creating the form of the chassis on the basis of the positioning of the antenna and the large inductors (for example, the latter tend to be very sensitive to nearby metal objects).
I shall never get tired of repeating that the theremin is a conceptually simple instrument that can be made with a handful of electronic components, but the influx that each section has on the others is often so difficult to control that, before managing to obtain a truly singing instrument, it is necessary to revise many times the design and assembly down to the finest detail.
If I can be allowed one final word, the dimension of a theremin builder would not have displeased the Italian Futurists contemporaries of Leon Theremin, art at the service of technology… and of course vice versa.