Photo courtesy of the Museum of Soviet Synthesizers, www.ruskeys.net
The Polivoks, or Polivox, is a monophonic (despite the name) analog synth produced in the Soviet Union in the 1980s. Designed by noted Russian musician / engineer Vladimir Kuzmin, the Polivoks is probably the best-known in the Western hemisphere of the numerous synths and electronic keyboard instruments produced in the Soviet Union, and it is highly sought after by collectors of Soviet-era instruments, as well as synth players who value it for its unique characteristics.
The architecture of the Polivoks consists of two voltage controlled oscillators, one voltage controlled filter of a unique design, one voltage controlled amplifier, two envelope generators, and one low-frequency oscillator. Both VCOs can produce triangle, sawtooth, and square waveforms, plus two pulse wave settings with different pulse widths (the pulse width cannot be modulated). VCO 2 can be detuned, and can cross modulate VCO 1. A duophonic mode is available, in which two notes can be played on the keyboard and each VCO will be driven by a different note. Envelope 1 is routed to the VCA, and envelope 2 is routed to the VCF. A white noise source is also available.
The two envelope generators are conventional ADSR types, but they each be switched to a continuous looping mode. EG 2 can also be disconnected from the VCA altogether, which allows the VCA to remain open in a drone mode; a played note will continue to sound indefinitely after the key is released. The LFO has four modes -- triangle, square, random, and a sample-and-hold of the noise source. The LFO can be routed to control either or both of the VCOs, the VCF cutoff frequency, or the VCA.
The most notable, and most copied, feature of the Polivoks is the VCF. Kuzmin worked out a way of using "programmable" operational amplifiers to behave as filters, and used this to implement a two-pole VCF that can be switched between low pass and bandpass mode. At high resonance settings, the filter self-oscillates in a particularly chaotic manner, unlike any Western design. Like the rest of the synth, the VCF is implemented using 1980s-era, Soviet-made integrated circuits, which makes precisely copying the behavior with contemporary Western-made parts difficult. Despite this, the circuit has been cloned by a number of Western makers; for instance, clones are available as modules from several modular synth manufacturers. Clones of the entire synth are also available.
The Polivoks is packaged as a keyboard instrument, having a 48-note, F-to-E span. There are no pitch or mod wheels. A portamento circuit is available, although oddly it effects VCO 1 only. Each VCO is available as an independent output, and there is also an external input to the VCF.
In Soviet style, the brand name of the Polivoks was taken from the manufacturing bureau responsible for manufacturing it, which was the Formanta radio factory. Some sources claim that over 100,000 were manufactured; in spite of this, the Polivoks is rare today, which tends to cast doubt on the production numbers. (Fudging production figures was widespread in the Soviet Union.) The VCOs lack temperature compensation and do not stay in tune very well, and the outputs use non-standard DIN connectors. And, as one might expect, the panel is notated in Russian. Despite all this, the Polivoks is widely sought out by a certain segment of the synth community.