Tiptop Audio Buchla 281t
Four Buchla envelopes with quadrature and cycling modes
28 HP Eurorack module
The Buchla 281t Quad Function Generator is a four-channel envelope and LFO generator organized in two pairs (A/B and C/D), capable of producing attack-decay, attack-sustain-decay, and cycling envelope shapes. Each generator outputs a voltage ramp from 0 to 10V with independently controllable attack and decay times, and the module can operate in Quadrature mode where paired generators run 90 degrees out of phase for complex modulation. Its musical character ranges from percussive transient shaping to slow evolving modulation and quadrature LFO duties.
Features
- Four independent function generators organized in two pairs: A/B and C/D
- Three envelope modes per pair: Transient, Sustained, and Cyclic
- Attack and Decay time range from 0.001 to 10 seconds per channel
- CV input with attenuator for both attack and decay modulation per channel
- Manual trigger button per channel for hands-on envelope firing
- Cycle jack per channel for gate-controlled cycling
- Pulse output per channel fires transient pulse at end of each decay segment
- Quadrature mode for A/B and C/D pairs: 90-degree phase offset between paired generators
- Pairs can be linked for more complex output voltages
- Output voltage ramps from 0V to 10V
- Eurorack format, 28HP, made by Buchla and Tiptop Audio collaboration
Controls & Jacks (60)
- Channel A Attack Time — Attack ramp time for Channel A function generator (0.001 to 10 seconds)
- Channel B Attack Time — Attack ramp time for Channel B function generator (0.001 to 10 seconds)
- Channel A CV In Attenuator — Attenuator for Channel A control voltage input affecting attack and decay rates
- Channel B Trigger — Manual trigger button for Channel B function generator
- Channel C Attack Time — Attack ramp time for Channel C function generator (0.001 to 10 seconds)
- Channel A Decay Time — Decay ramp time for Channel A function generator (0.001 to 10 seconds)
- Channel D Attack Time — Attack ramp time for Channel D function generator (0.001 to 10 seconds)
- Channel C Trigger Input — Trigger input jack for Channel C function generator
- Channel B Decay Time — Decay ramp time for Channel B function generator (0.001 to 10 seconds)
- Channel C Decay Time — Decay ramp time for Channel C function generator (0.001 to 10 seconds)
- Channel B Trigger Input — Trigger input jack for Channel B function generator
- Channel C Trigger — Manual trigger button for Channel C function generator
- Channel A Cycle Input — Gate input jack to enable cycling of Channel A function generator
- Channel D CV In Attenuator — Control voltage input for Channel D attack and decay time modulation
- Channel A Output — Main voltage output of Channel A function generator (0-10V)
- Channel A Pulse Output — Transient pulse output at the end of Channel A decay segment
- Channel D Decay Time — Decay ramp time for Channel D function generator (0.001 to 10 seconds)
- Channel D Pulse Output — Transient pulse output at the end of Channel D decay segment
- Mode Switch A-B — Selects one of three modes for Channels A-B pair: Transient, Sustained, or Cyclic
- Channel C Cycle Input — Gate input jack to enable cycling of Channel C function generator
- Mode Switch C-D — Selects one of three modes for Channels C-D pair: Transient, Sustained, or Cyclic
- A
- Quadrature A Output — Quadrature mode output for Channel A (90-degree phase shift)
- Channel B CV In Attenuator — Attenuator for Channel B control voltage input affecting attack and decay rates
- Channel B CV In — Control voltage input for Channel B attack and decay time modulation
- Channel B Output — Main voltage output of Channel B function generator (0-10V)
- outs 1
- Channel C CV In — Control voltage input for Channel C attack and decay time modulation
- Channel C Output — Main voltage output of Channel C function generator (0-10V)
- Channel A Trigger Input — Trigger input jack for Channel A function generator
- Channel C Pulse Output — Transient pulse output at the end of Channel C decay segment
- Quadrature C Output — Quadrature mode output for Channel C (90-degree phase shift)
- Quadrature Mode Button A-B — Engages Quadrature mode for Channels A and B, shifting functions by 90 degrees
- Channel B Pulse Output — Transient pulse output at the end of Channel B decay segment
- Quadrature B Output — Quadrature mode output for Channel B (90-degree phase shift)
- Quadrature D Output — Quadrature mode output for Channel D (90-degree phase shift)
- outs 2
- Channel D Cycle Input 1 — Gate input jack to enable cycling of Channel D function generator
- Channel D Output — Main voltage output of Channel D function generator (0-10V)
- Channel D Trigger — Manual trigger button for Channel D function generator
- Channel B Cycle Input — Gate input jack to enable cycling of Channel B function generator
- Channel D Cycle Input 2 — Gate input jack to enable cycling of Channel D function generator
- Channel A CV In — Control voltage input for Channel A attack and decay time modulation
- Channel D Trigger Input — Trigger input jack for Channel D function generator
- M
- C
- TO 1
- M 1
- M 2
- Channel A Trigger — Manual trigger button for Channel A function generator
- Channel A Cycle Input — Gate input jack to enable cycling of Channel A function generator
- Quadrature Mode Button C-D — Engages Quadrature mode for Channels C and D, shifting functions by 90 degrees
- cycle
- TO 2
- ON
- Channel C CV In Attenuator — Attenuator for Channel C control voltage input affecting attack and decay rates
- Mode Switch (A-B) — Selects one of three modes for Channels A-B pair: Transient, Sustained, or Cyclic
- Mode Switch (C-D) — Selects one of three modes for Channels C-D pair: Transient, Sustained, or Cyclic
- Quadrature Switch (A-B) — Engages Quadrature mode for Channels A and B, shifting functions by 90 degrees
- Quadrature Switch (C-D) — Engages Quadrature mode for Channels C and D, shifting functions by 90 degrees
How-To Guides
- Classic Percussive Envelope
- Gate-Responsive ADSR-Style Envelope
- Slow Cyclic LFO for Modulation
- Quadrature LFO for Auto-Panning
- Cascading Envelope Chain
- Audio Rate Function Oscillator
- CV-Controlled Rate LFO
- Dual Quadrature Complex Modulation
- Gate-Gated LFO Cycling
Explore the interactive Buchla 281t panel on BleepDex — tap any control to learn what it does.
