Friday, October 30, 2020


via this auction

"Monophonic synthesizer Altair 231 (Estradin factory, Zhitomir city) is intended to play different sounds from the imitation of natural instruments to complicated synthesized electronic timbres, sound effects, percussion sounds & so on. There are a four-octave keyboard & a wheel to pitch control. There are also controls for parameters on the front panel, an output for phones, an input for a pedal. The instrument consists of four main blocks of sound synthesis - Generator, Mixer, Filter and Contour.

Synthesis is based on 3 master oscillators (each of them with different parameters of registers) waveform, frequency modulation. There is also a generator of white & pink noise. Low-pass filter with main parameters gives the possibility for keyboard tracking. Portamento adjustment knob is provided. To tune a pitch the tone signal is used (440Hz) It provides a linear input to connct an external sound source to Altair. Output and input sockets are 1/4" jacks

Altair 231 is an almost identical copy of the famous Moog Minimoog, made in the former Soviet Union. Biggest difference in sound is caused by different brand of components: Russian equivalents are used everywhere.

The oscillator board is based on the older version. However, the Russians were clever and used multi-turn potentiometers for the scaling controls. Result: Synth stays in tune better. The Russians didn't seem to have reverse log pots. Because of that, the resonance control was wired backwards and a regular logarithmic pot was used instead. Other than that, the synth seems to be very robust and easy to service - the real Mini schematics come for good help when comparing the component numbers etc. It sounds like a Mini! I heard a Mini with the newer oscillator board and I think that's the reason for minor differences in sound between it and the Altair.

It is a monophonic 3 OSC analog synthesizer. Synth has 4-oct keyboard (F-C) with velocity (sensitivity assign to vibrato effect). The synthesizer has based on 3 VCO (osc. No.3 can work as the modulator), 1 VCF (lowpass 24dB/oct)with ADSR, 1 VCA, 3 LFO, noise generator (white/pink), portamento, memoryloop. It has an EXTERNAL INPUT allowing to use FILTER and GENERATORS with external audio INPUT.

OSCILLATORS section: - 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 (osc 3 ONLY) MIXER: - osc 1,2,3 on/off, level - ext input level, on/off - noise generator level, on/off - noise mode switch: white/pink MOD section: - portamento on/off, rate; - mod mixer knob: balance between modulated by OSC3 and noise, depth amount; - pitch wheel (glissando)

FILTER: - mod on/off - cutoff, resonance, brightness - attack, decay, sustain - keytrack on/off

AMPLIFIER: - attack, decay, sustain - key hold memory on/off Next - global section: main volume, phones volume, phones out (5din), A-440Hz tone on/off, power. Connections :

Audio OUTPUT, Audio INPUT on standard 1/4''jack, pedal input on 5-Din socket , power wire connection (220/240V), fuse (0,5A) ."

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