A-170

Doepfer 8HP
SLEW ENVELOPE UTILITY

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Dual slew limiter (portamento controller). Upper SL has single joint rise/fall time knob. Lower SL has independent rise and fall controls with 3-position time range switch for AR envelope use.

Patch Ideas · 4

Portamento generator
MIDI-CV → Upper SL In · Out → VCO 1V/oct · Time knob sets glide
Walkthrough
  1. Patch your MIDI-CV or keyboard pitch CV into the Upper SL In jack.
  2. Patch Upper SL Out into your VCO's 1V/oct input.
  3. Start with the Time knob fully counter-clockwise (0 = no glide).
  4. Play two notes far apart, then slowly turn Time clockwise until the pitch glides noticeably between them.
  5. Use the Upper SL (not the lower one) for precision pitch — the lower SL has a ~0.5V diode offset that breaks 1V/oct tracking.
Signal out Out (Upper SL) — smoothed pitch CV that lags behind the incoming notes by the Time setting.
Listen for Each note slides into the next instead of jumping. Short Time settings feel like a subtle legato; longer settings give a cartoonish glide.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: A-170, MIDI-CV, VCO. Signals: 2 pitch.A-170MIDI-CVVCOTime (Upper SL): to tasteIn Upper SL1v/octOut Upper SL1v/octCV1v/oct1V/oct1v/oct11. glide amount set by Timepitch
AR envelope for bass
Gate → Lower SL In · Rise/Fall set individually · Out → VCA CV
Walkthrough
  1. Flip the Time Range switch to M (medium, 0–10s).
  2. Patch a gate from a sequencer or keyboard into the Lower SL In jack.
  3. Patch Lower SL Out into your VCA's CV input.
  4. Set the Rise (up arrow) knob low for a snappy attack.
  5. Set the Fall (down arrow) knob around 9 o'clock for a short tail.
  6. Play notes and tweak Rise/Fall until the envelope shape feels musical.
  7. If the envelope is too slow or too fast overall, switch Time Range to L (faster) or H (slower).
Signal out Out (Lower SL) — unipolar AR envelope following each incoming gate (starts from ~0.5V offset, not true 0V).
Listen for A classic attack-release bass shape. Short Rise gives a punchy pluck; longer Rise turns it into a swell. The Fall controls how long the note rings out.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: A-170, Gate Source, VCA. Signals: 1 cv, 1 gate.A-170Gate SourceVCATime Range (Lower SL): MIn Lower SLgateOut Lower SLcvGategateCVcv11. AR shape from Rise/Fall knobscvgate
Glissando AM
Pitch CV → VCO1 direct & via Upper SL → VCO2 (modulator) · produces timbral sweep
Walkthrough
  1. Multiple your keyboard or sequencer pitch CV into two destinations.
  2. Patch one copy straight to VCO1's 1V/oct input (this is the carrier).
  3. Patch the other copy into the Upper SL In jack.
  4. Patch Upper SL Out to VCO2's 1V/oct input (this is the modulator).
  5. Tune VCO1 and VCO2 to a harmonically related interval (octave, fifth).
  6. Patch VCO2's output into a VCA CV input; feed VCO1 through that VCA.
  7. Set the Upper SL Time knob so the glide is shorter than your shortest note.
  8. Play notes: VCO1 jumps instantly, VCO2 glides, producing a timbral sweep on each note.
Signal out Out (Upper SL) — pitch CV that lags the played note, sent to VCO2 so the modulator catches up to the carrier during each note.
Listen for Every new note starts with a bright AM-style warble that settles into a clean tone as VCO2 arrives at pitch. Shorter Time = quick chirp; longer Time = longer sweep.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 4 connections. Modules: A-170, Pitch CV, VCO1, VCO2, VCA1. Signals: 1 cv, 3 pitch.A-170Pitch CVVCO1VCO2VCA1In Upper SL1v/octOut Upper SL1v/octCV1v/oct1V/oct1v/oct1V/oct1v/octOutcvCVcv121. lagged pitch for AM sweep2. modulator controls VCA1cvpitch
Complex envelope from clock sequencer
A-161 outputs trigger Upper SL and Lower SL on one or more A-170s · envelopes mixed in A-138a · complex evolving shape
Walkthrough
  1. Feed an LFO or MIDI clock into the A-160 clock divider, which drives the A-161 sequencer.
  2. Patch A-161 output 1 (gate) into the Upper SL In jack.
  3. Patch A-161 output 8 (or any other) into the Lower SL In jack.
  4. Set the Upper SL Time knob for a long, slow ramp.
  5. Set Lower SL Time Range to M and dial in contrasting Rise/Fall times.
  6. Patch both A-170 outputs into separate inputs of a linear mixer like the A-138a.
  7. Patch the mixer output to a VCF cutoff or VCA CV.
  8. Add more A-170s on other A-161 outputs to build richer stacked envelopes.
Signal out A-138a Out — summed stack of staggered AR/slew envelopes, one per A-161 output you used.
Listen for A continuously evolving CV landscape. Each sequencer step fires a different envelope, and overlapping tails at the mixer create shapes you cannot draw with a single envelope generator.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 5 connections. Modules: A-170, A-161, A-138a, VCF. Signals: 3 cv, 2 gate.A-170A-161A-138aVCFTime (Upper SL): slowTime Range (Lower SL): MIn Upper SLgateIn Lower SLgateOut Upper SLcvOut Lower SLcvOut 1gateOut 8gateIn 1cvIn 4cvOutcvCutoffcvcvgate

Behaviors

Portamento pitch CV → In

Smooths pitch CV for glide effect. Upper SL recommended for precision pitch work; lower SL has ~0.5V diode offset unsuitable for 1V/oct.

AR Envelope Generator gate → Lower SL In

Lower SL with separate rise/fall controls acts as an AR envelope generator when a gate signal is applied.

Complex Envelope Mixing clock sequencer → multiple SLs

Clock sequencer triggers multiple A-170 units whose envelope outputs are mixed in a linear mixer, creating complex evolving envelopes.

Controls

Upper SL Time Sets both rise and fall time jointly for the upper slew limiter.
0–10 seconds
Lower SL Rise (up arrow) Sets rise time for the lower slew limiter, within range set by Time Range switch.
L: 0–0.5s · M: 0–10s · H: 0–minutes
Lower SL Fall (down arrow) Sets fall time for the lower slew limiter, within range set by Time Range switch.
L: 0–0.5s · M: 0–10s · H: 0–minutes
Lower SL Time Range 3-position switch sets overall time range for lower SL rise and fall.
L = low (fast) · M = medium · H = high (slow)

I/O

IN · 2

  • In (Upper SL) any CV CV
    Signal input for the upper slew limiter.
  • In (Lower SL) any CV CV
    Signal input for the lower slew limiter.

OUT · 2

  • Out (Upper SL) follows input
    Slew-limited output of the upper slew limiter.
  • Out (Lower SL) follows input (note ~0.5V offset due to diodes)
    Slew-limited output of the lower slew limiter.