Studio Electronics ATC-Xi - Quad Filter System SN 1260

via this auction

"Studio Electronics ATC-Xi - Quad Filter System - Discrete Analog Monophonic Synthesizer --- In excellent condition! 100% functional! Looks excellent!
This is a beast. A bass and lead monster.
All four filters present: Moog 24db Lowpass, Oberheim 12db lowpass and bandpass, 303 Lowpass and ARP lowpass. Oscillator 1 has a sine waveform instead of the usual triangle waveform. Switchable VCAs from ATC-X's Moog Source transistor array style or the classic SE-1X fully discrete Minimoog style amplifier from front switch. Built in analog distortion."