More pix - here

ALTAIR-231 is a monophonic 3-osc power synthesizer produced by Estradin RIP radioplant located in Zhitomir city. Synthesizer has 4-oct keyboard (F-C) with velocity sensitivity assign to vibrato effect. Sound control is performed with round knobs and switchers. For live performance there is a wheel which provides pitch shift (called glissando).
Synthesizer is based on 3 VCO (any can work as the modulator), 1 VCF (lowpass 24dB/oct) with ADSR, 1 VCA, 3 LFO, noise generator (white/pink), portamento.
Consist of 5 main sections - MODULATION, OSC'S, MIXER, FILTER and AMP (called Contour).

MOD section:
- portamento on/off, rate;
- mod mixer knob: balance between modulated by OSC3 and noise, depth amount;
- vibrato on/off, octave shift to 1/2
- pitch wheel (glissando)
- osc 1,2,3 registers - 2", 4", 8", 16", 32", LF
- osc 1,2,3 waveshape select - triangle, saw, square, pulse, sine
- osc frequency - freq 1..3, freq 2, freq 3 -linked to keyboard pitch on/off
- modulation on/off switch
- osc 1,2,3 on/off, level
- ext input level, on/off
- noise generator level, on/off
- noise mode switch: white/pink
- mod on/off
- cutoff, resonance, brightness
- attack, decay, sustain
- keytrack on/off
- attack, decay, sustain
- key hold memory on/off
Next - global section: main volume, phones volume, phones out (5din), A-440Hz tone on/off, power.
Connection 1/4 jacks: input, output, pedal input (5din), ground.
Power supply: 220V/50Hz, fuze 0,125A

The synthesizer has a label of the Soviet "State Sign of Quality".

Sound phrases - sample1  sample2  sample3  sample4  sample5

Schematics - map1  map2  map3  map4  map5  map6  map7  map8

Panel translation - here

Knobs translation - click here