I'm doing a college assignment on the history of Synthesizers and am wondering what type of synthesis a theremin would be classed under... Like is it subtractive, additive etc.
Any help would be much appreciated as I'm stuck as hell!
What type of syntheses category does a Theremin fall under?
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- KVRAF
- 35297 posts since 14 Sep, 2002 from In teh net
I think it's a form of amplitude modulation
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- KVRAF
- 35297 posts since 14 Sep, 2002 from In teh net
Just looked it up
http://electronicmusic.wikia.com/wiki/Theremin
http://electronicmusic.wikia.com/wiki/Theremin
The theremin is unusual in that, in the process of playing, the performer does not touch it. The instrument has two metal rods or loops that protrude from its box; these are antennas attached to an oscillator that is running in the 100-200 KHz range. Moving a hand (or any other body part) alters the electric field around the antenna, which slightly alters the frequency of the oscillator. Within the box, the oscillator beats against a reference oscillator (in a process similar to amplitude modulation) to create an audio-frequency tone, which is separated from the RF frequencies and sent to an amplifier.
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- KVRAF
- 3080 posts since 17 Apr, 2005 from S.E. TN
Haven't intensely studied theremins.
So far as I know classic early theremin would beat radio frequency sine waves against each other, and assuming the process was absolutely clean distortion-free, the lower audible difference frequency would be a sine wave.
Because hardly any analog signal is really a pure undistorted sinewave, especially back when theremins were invented, the reality would have richer harmonic content. As best I recall, theremins and other early "sine wave like" instruments often had passive filter networks which could be switched-in, to make bright, dull, or "vowel-like" tones.
The basic audio signal from the radio circuit would need more harmonic content than a pure sine wave, or those passive voicing circuits wouldn't have anything to work with. On a pure sine wave, undistorted filters only act as volume controls, not changing the timbre at all.
Maybe the early ones had sufficient natural built-in distortion to supply enough harmonics for a crude voicing filter to work against? Or maybe distortion had to be intentionally added, in order to shape the signal into "harmonic-rich" enough to allow voicing with passive filters?
Dunno.
I think some of the later theremins had added processing to generate typical square, tri, ramp type synth waves, but never studied them much.
So far as I know classic early theremin would beat radio frequency sine waves against each other, and assuming the process was absolutely clean distortion-free, the lower audible difference frequency would be a sine wave.
Because hardly any analog signal is really a pure undistorted sinewave, especially back when theremins were invented, the reality would have richer harmonic content. As best I recall, theremins and other early "sine wave like" instruments often had passive filter networks which could be switched-in, to make bright, dull, or "vowel-like" tones.
The basic audio signal from the radio circuit would need more harmonic content than a pure sine wave, or those passive voicing circuits wouldn't have anything to work with. On a pure sine wave, undistorted filters only act as volume controls, not changing the timbre at all.
Maybe the early ones had sufficient natural built-in distortion to supply enough harmonics for a crude voicing filter to work against? Or maybe distortion had to be intentionally added, in order to shape the signal into "harmonic-rich" enough to allow voicing with passive filters?
Dunno.
I think some of the later theremins had added processing to generate typical square, tri, ramp type synth waves, but never studied them much.
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- KVRAF
- 7364 posts since 9 Jan, 2003 from Saint Louis MO
Here are the waveforms of a Moog Etherwave (1995 and later) theremin with the "brightness" and "waveform" knobs in different positions (not my image or research):
From what Google Images shows, it seems most theremins don't deviate far from a sine, with some but not a lot of harmonic distortion.
The newest Moog "Theremini" is an exception, since it's an analog-controlled digital instrument.
From what Google Images shows, it seems most theremins don't deviate far from a sine, with some but not a lot of harmonic distortion.
The newest Moog "Theremini" is an exception, since it's an analog-controlled digital instrument.
