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Mono - Image 1

Mono

KeyboardAnalogMonophonic

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.

Released

1980

Status

Discontinued

Synthesizer
Format
Keyboard
Type
Subtractive
Internal Battery
No
Voice
A/D
Analog
Polyphony
Monophonic
Oscillators
1
Oscillator Type
DCO (Digitally Controlled)
Voices
1
Filter
Lowpass, Highpass, Bandpass, Resonant
Envelopes
1
LFO
1
Effects
Chorus
Expression
Aftertouch
No
Velocity
No
MPE
No
Additional
-
Software
-
I/O
Audio In
-
Audio Out
1 mono
Headphone
-
MIDI
-
MIDI Type
-
Ports
-
Wi-Fi
No
Workflow
Arpeggiator
-
Sequencer
-
Mod Matrix
-
Memory
10 presets: Basso tuba, Trombone, Trumpet, Flute, Piccolo, Sax, Clarinet, Violin, Bass and Guitar.
Measurements
Dimensions
-
Weight
7 kg
Last updated Mar 21, 2026