Leon Theremin introduces and performs three songs on the so-called Polyphonic Theremin. This consists of playing the theremin while simultaneously operating (by the left hand) an instrument for harmonic accompaniment. The recording was made in the 1970s–1980s by Sergey Zorin.
The Instrument for Pure Harmonic Accompaniment of Melodic Performance (on the photo) was developed by Leon Theremin. The photograph comes from the archive of the Acoustics Laboratory of the Moscow Tchaikovsky Conservatory.
The instrument is designed to provide pure harmonic accompaniment to melodic performance. It enables a performer to accompany a freely intonated melody with harmonies based on natural intervals (Pythagorean Tuning). Through a keyboard, the performer can select from 22 different pure intervals to create the desired harmonic accompaniment.
The instrument operates on the principle of a light siren. Its rotational speed is determined by the fundamental pitch of the melody being performed. This provides a basis for generating the corresponding harmonic tones. The performer then uses the keyboard to select the desired intervals and construct the harmonic accompaniment.
An important feature of the instrument is the ability to control the intensity of each individual harmonic tone. The depth to which each long-travel key is pressed determines the intensity of the corresponding pitch. This is achieved electronically through amplitude modulation, by varying the amplifier bias according to the degree of resonance.
By combining different pitches at different intensities, the instrument can produce a wide range of harmonic colours and dynamic effects, analogous to the variety of timbres found in conventional musical instruments.
The instrument was never completed and has not survived.
The songs Lev Theremin announces and plays on the recording:
00:01 – “The Red Sarafan,” composed by A. Varlamov
00:51 – “We venerate Your Cross, O Lord, and glorify Your holy Resurrection,” church chant.
00:55 – “May their memory be eternal,” church chant.
