Eurorack Reference

Whimsical Raps (Mannequins) / whimsical-raps/three-sisters

Three Sisters

Three interrelated filters (LOW, CENTRE, HIGH) with linked cutoff frequency control via FREQ and SPAN, switchable between crossover and formant modes, with individual and global inputs/outputs. [22]

Specifications

HP
10
Depth
30 mm
+12V
100 mA
−12V
93 mA
+5V
—
Last verified
2026-05-02

Capabilities

  • 2-Operator FM Synthesis fm-synthesis
    Self-patch CENTRE(OUT) to SPAN in formant mode with QUALITY at max for 2-operator FM; CENTRE is the modulator, LOW and HIGH are carriers. [22]
  • Formant and Vowel Synthesis formant-synthesis
    In formant mode with ALL(IN) and ALL(OUT), THREE SISTERS acts as three parallel bandpass filters whose bands can be positioned with FREQ/SPAN and narrowed with QUALITY for vowel/formant synthesis. [22]
  • Multimode Filter multimode-filter
    Three cascaded SVF filter blocks (LOW, CENTRE, HIGH), each pair configurable as crossover mode (lowpass/crossover/highpass) or formant mode (three bandpass filters). [22]
  • Self-Oscillation self-oscillation
    All three filter blocks self-oscillate at their respective cutoff frequencies when QUALITY is at approximately 3 o'clock, producing sine waves usable for FM and filter pinging. [22]
  • Spectral Mixing spectral-mixing
    In crossover mode, three distinct inputs (LOW(IN), CENTRE(IN), HIGH(IN)) are each filtered into their own spectral band, mixed at ALL(OUT) for spectral mixing. [22]

Jacks (12)

Inputs (8)

NameSignalVoltageDescription
ALL(IN) audio — Input that feeds a signal into all three filter blocks simultaneously. [22]
CENTRE(IN) audio — Direct audio input to the CENTRE filter block. [22]
FM mixed — Frequency modulation CV input; passes through an attenuverter before being added to FREQ. Accepts both control-rate and audio-rate modulation. [22]
FREQ CV cv — Volt-per-octave CV input for FREQ; 1V increase doubles all cutoff frequencies. Tracks accurately over ~5 octaves. [22]
HIGH(IN) audio — Direct audio input to the HIGH filter block. [22]
LOW(IN) audio — Direct audio input to the LOW filter block. [22]
QUALITY CV cv -5V to 5V CV input for QUALITY (resonance); added to knob value. -5V to +5V with knob at noon spans full CCW to full CW range. [22]
SPAN CV cv — CV input for SPAN; added to the SPAN knob value. [22]

Outputs (4)

NameSignalVoltageDescription
ALL(OUT) audio — Equal mix of all three filter block outputs. [22]
CENTRE(OUT) audio — Individual output of the CENTRE filter block. In crossover mode: passes band between LOW and HIGH cutoffs (12dB/oct rolloffs). In formant mode: 12dB/octave bandpass at FREQ. [22]
HIGH(OUT) audio — Individual output of the HIGH filter block. In crossover mode: 24dB/octave highpass. In formant mode: 12dB/octave bandpass. [22]
LOW(OUT) audio — Individual output of the LOW filter block. In crossover mode: 24dB/octave lowpass. In formant mode: 12dB/octave bandpass. [22]

Parameters (5)

NameTypeRangeMin FWBehavior
FM Attenuverter knob — — Attenuverter for the FM CV input; scales and optionally inverts the FM signal before it is added to FREQ. [22]
FREQ knob — — Controls the base cutoff frequency for all three filter blocks simultaneously. CV input is volt-per-octave; 1V increase doubles all cutoff frequencies. [22]
Mode Switch switch — — Selects between crossover mode (LOW=24dB/oct lowpass, CENTRE=crossover bandpass, HIGH=24dB/oct highpass) and formant mode (all three filters are 12dB/oct four-pole bandpass filters). [22]
QUALITY knob — — At noon, resonance is at minimum. Clockwise increases resonance; at ~3 o'clock filters self-oscillate producing sine waves. Counter-clockwise from noon mixes complementary (rejected) filter output back in, creating notch and dry/wet blending effects. [22]
SPAN knob — — Pushes LOW and HIGH cutoffs in opposite directions around the FREQ centre-point. In crossover mode, widens/narrows the CENTRE passband. In formant mode, CENTRE bandpass is unaffected by SPAN. [22]

Firmware history (0 versions)

No firmware history recorded.

References (2)