Mono

Back in 1980, this Italian gem emerged as one of the rarest monophonic synths from Siel, packing a single DCO into a compact 7kg frame that punches way above its weight for raw, gritty analog tone.

A 37-key keyboard anchors the setup, feeding into one digitally controlled oscillator based on the M110B1 chip, complete with pink noise mix for extra character. The star is its multimode resonant VCF—switchable between lowpass, highpass, and bandpass—with dedicated cutoff and resonance sliders, shaped by a single ADSR envelope assignable to amp, filter, or both. Modulation comes from a delayed triangle LFO targeting pitch or cutoff, plus an onboard analog chorus called "Animator" for instant depth. Controls scatter across 32 sliders, a horizontal pitchbend joystick, and preset buttons for 10 factory sounds like Basso Tuba or Sax, with a "Free" mode for tweaking.

Owners can't get enough of its roaring basses, cathedral-like clarinet tones, and filthy filter sweeps—perfect for leads or pads that rival pricier monos. It's a quirky, hands-on workhorse that's built a cult following among vintage hunters.