Novation A Station
This used A Station is fully functional and in very good condition.
The A-Station is polyphonic, adding 8 voices of polyphony to their 1-unit rack-mount synth. Unlike the original Bass Station and Super Bass Station which were real analog synths, the A-Station gets its voice architecture from the SuperNova synths, which use analog sound modeling. The A-Station has the layout and shape of the famous Bass Stations, but its guts are basically a slimmed down SuperNova.
It has 25 knobs for real-time control, and all knobs transmit MIDI controller messages. The A-Station has three oscillators which provide sawtooth, triangle, sine and pulse width modulation. There's even a simple FM synth engine which can be dialed in for sharpening the sound. Oscillators may be set to Unison or Sync'd operation and a Noise source is also included in the waveform engine. There is a nice lowpass resonant filter with switchable 12 or 24dB/oct slopes and ADSR controls. A second ADSR envelope is available for the oscillators, as well as two LFOs with sample-and-hold and MIDI sync.