SLEW

Befaco 4HP
SLEW FUNCTION UTILITY

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Voltage-controlled lag processor with independent rise and fall faders · three-position speed range · linear-to-time-compensated SHAPE · rising and falling gate outputs from onboard slope detector · <1mV pitch tracking error.

Patch Ideas · 6

★ Classic acid slide
Sequencer pitch → IN · RISE low · FALL low · SHAPE full CW for time-compensated glide · OUT → VCO V/Oct · short glides between steps regardless of interval size · sub-mV tracking keeps tuning locked
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: SLEW, Sequencer, VCO. Signals: 2 pitch.SLEWSequencerVCORISE: lowFALL: lowSHAPE: full CWRANGE: middleIN1v/octOUT1v/octPitch1v/octV/Oct1v/octpitch
Gate into ASR envelope
Gate → IN · RISE = attack · FALL = release · OUT → VCA CV · sustain = gate voltage · free AR/ASR envelope from any gate source · use RANGE middle for musical timings
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: SLEW, Clock, VCA, VCO. Signals: 1 audio, 1 cv, 1 gate.SLEWClockVCAVCORISE: attack timeFALL: release timeSHAPE: CCW (linear)RANGE: middleINgateOUTcvOutgateInaudioCVcvOutaudioaudiocvgate
Up/down event detector
LFO → IN · RISING and FALLING gates drive separate envelopes · each half of the LFO fires a different event · use on slow random CV to generate rhythmic triggers tied to voltage direction
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: SLEW, LFO, Envelope A, Envelope B. Signals: 1 cv, 2 trigger.SLEWLFOEnvelope AEnvelope BRISE: lowFALL: lowRANGE: fastestINcvRISINGtrigFALLINGtrigOutcvTrigtrigTrigtrigcvtrigger
★ Voltage-controlled glide depth
Sequencer pitch → IN · OUT → VCO · expression pedal or LFO into CV · switch to RF to modulate both rise and fall · RISE and FALL faders set max glide time · dynamic portamento that opens and closes under CV
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: SLEW, Sequencer, LFO, VCO. Signals: 1 cv, 2 pitch.SLEWSequencerLFOVCORISE: midFALL: midCV switch: RFSHAPE: 2 o'clockIN1v/octCVcvOUT1v/octPitch1v/octOutcvV/Oct1v/octcvpitch
Asymmetric kick envelope
Trigger → IN · RISE almost zero for punchy attack · FALL moderate for body · SHAPE CCW for linear decay · OUT → VCA and filter cutoff · no dedicated envelope needed for simple percussive shapes
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 5 connections. Modules: SLEW, Clock, VCO, Filter, VCA. Signals: 2 audio, 2 cv, 1 trigger.SLEWClockVCOFilterVCARISE: 0 (instant)FALL: midSHAPE: CCWRANGE: fastestINtrigOUTcvOuttrigOutaudioInaudioCutoffcvOutaudioInaudioCVcvaudiocvtrigger
★ Smooth sample-and-hold
S&H output → IN · RANGE middle, RISE and FALL matched · OUT → filter cutoff · stepped random becomes smooth random contour · SHAPE 2 o'clock so big jumps still arrive on time
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: SLEW, S&H, Filter. Signals: 2 cv.SLEWS&HFilterRISE: midFALL: midSHAPE: 2 o'clockRANGE: middleINcvOUTcvOutcvCutoffcvcv

Behaviors

Time-compensated portamento SHAPE turned fully clockwise with pitch CV on IN

Rate of change scales with note-to-note distance so wide intervals glide in roughly the same time as small ones. Keeps acid-line slides musical across the keyboard instead of dragging on large leaps.

Gate-to-ASR envelope gate patched to IN with RISE and FALL set above zero

Rising edge climbs at the rise rate, gate-high holds at the gate voltage (sustain), falling edge decays at the fall rate. One fader per segment gives attack and release without a dedicated envelope module.

Slope-driven event gates signal moving on IN

RISING outputs a gate while OUT climbs, FALLING while it drops. Use to trigger envelopes or advance a counter whenever a melody moves up or down. Sensitivity rises with the RANGE switch toward fastest — tighten RISE/FALL to kill ghost gates from ripple.

Faders as CV attenuators CV patched to CV input

RISE and FALL faders stop being absolute times and become attenuators scaling CV IN into that parameter. Lower the fader to reduce modulation depth without needing an external attenuator.

Ghost-gate taming RANGE on fastest with quiet source

At minimum slew the detector catches sub-mV ripple and outputs unwanted gates. Raise slew time or the RANGE switch until the gates lock to intentional transitions only.

Linear vs distance-driven response SHAPE position

CCW keeps dV/dt constant — classic slew. As SHAPE opens, larger input jumps become proportionally faster, preventing long glides from feeling flat. Mid-position sits between the two for hybrid behaviour.

Controls

Global RISE Fader sets rise slew time. Also attenuates CV IN when the CV selector routes to rise.
bottom: instant · top: max range · doubles as CV attenuator
Global FALL Fader sets fall slew time. Also attenuates CV IN when the CV selector routes to fall.
bottom: instant · top: max range · doubles as CV attenuator
Global SHAPE Morphs curve from linear to time-compensated. CW increases the rate of change as the gap between IN and OUT grows.
CCW: linear (constant dV/dt) · CW: distance-driven · time-compensated portamento at full CW
Global RANGE Three-position switch selecting the overall slew time scale.
left: fastest · middle · right: slowest
CV IN routing R / RF / F Three-position switch selecting whether CV IN modulates RISE only, both, or FALL only.
up (R): rise · center (RF): both · down (F): fall

I/O

IN · 2

  • IN -10V to +10V CV
    Signal to be slewed. Tracks pitch CV with <1mV error so portamento stays in tune.
  • CV 0 to +10V CV
    CV over slew time. Destination set by the R/RF/F switch; attenuated by the matching fader.

OUT · 3

  • OUT GATE
    Slew-limited copy of IN. Converts a gate into an ASR-style envelope when RISE and FALL are set to taste.
  • RISING GATE
    Gate high while OUT is rising. Slope detector sits after the slew so sensitivity scales with the current slew time.
  • FALLING GATE
    Gate high while OUT is falling. Same detector as RISING, mirrored polarity.