intellijel-bifold

Intellijel Bifold

Dual Buchla and Serge wavefolder with crossfade and feedback

8 HP Eurorack module

Bifold is a dual-channel wavefolder combining a Buchla-inspired parallel 'deadband' folder (P channel) and a Serge-inspired serial folder (S channel). The two circuits have distinct harmonic characters that can be blended, crossfaded, and feedback-routed for a rich palette of complex waveforms and evolving timbres. Beyond wavefolding, the module supports ring modulation, amplitude modulation, stereo folding, and chaotic noise generation via internal feedback.

Features

  • Dual independent wavefolder channels: P channel (Buchla-inspired parallel deadband) and S channel (Serge-inspired serial)
  • Single FOLD knob controls both channels simultaneously with per-channel attenuators
  • CV inputs for FOLD P and FOLD S with ±10V range and internal +5V normal when unpatched
  • XFADE crossfader blends P and S outputs at MIX output with CV control
  • XFADE P and XFADE S source selectors: choose folded or dry (unfolded) signal per side
  • SYM-X-AUX switch per channel: add DC symmetry offset or external AUX signal to folder input
  • SYM-AUX attenuverter per channel for DC offset or AUX signal scaling
  • PHASE invert switch on S-side XFADE input for ring and amplitude modulation
  • AUX IN normalled to MIX output when unpatched — enables internal feedback patching
  • IN S normalled to IN P when unpatched
  • FOLD S CV normalled to FOLD P CV when unpatched
  • Bicolor LEDs (red=negative, green=positive) for OUT P, OUT S, and MIX outputs

Controls & Jacks (30)

  • FOLD— Sets the initial amount of wave folding applied to both parallel and serial folders. Modulated by FOLD P and FOLD S CV inputs.
  • FOLD P Attenuator— Attenuates CV input to FOLD P. Fully clockwise = full CV, fully counterclockwise = no CV. Internally normals +5V when no jack connected.
  • SYM-X-AUX P— Selects signal source for parallel folder: SYM adds DC offset for symmetry control, AUX mixes AUX input, X disables external modulation.
  • AUX— Auxiliary input mixed into parallel or serial folder when SYM-X-AUX switch is in AUX position. Normalled to MIX output if unpatched.
  • OUT P— Output of the parallel (Buchla-style) wavefolder circuit.
  • IN S— Input to the serial (Serge-style) wavefolder circuit. Normalled to IN P if unpatched.
  • FOLD S Attenuator— Attenuates CV input to FOLD S. Fully clockwise = full CV, fully counterclockwise = no CV. Internally normals +5V when no jack connected.
  • XFADE— Controls the relative mix of the parallel and serial folders at the MIX output. Fully counterclockwise = parallel only, fully clockwise = se
  • SYM-AUX Attenuverter S— Attenuates DC offset (SYM mode) or AUX input (AUX mode) for the serial folder. No effect in X mode.
  • OUT P LED— Indicates signal presence at OUT P. Brightness shows amplitude, color indicates polarity (red=negative, green=positive).
  • IN P— Input to the parallel (Buchla-style) wavefolder circuit.
  • MIX— Output of the crossfaded mixture of parallel and serial folder circuits.
  • OUT S— Output of the serial (Serge-style) wavefolder circuit.
  • SYM-X-AUX S— Selects signal source for serial folder: SYM adds DC offset for symmetry control, AUX mixes AUX input, X disables external modulation.
  • OUT S LED— Indicates signal presence at OUT S. Brightness shows amplitude, color indicates polarity (red=negative, green=positive).
  • XFADE Attenuverter— Attenuates CV input to XFADE. Fully clockwise = normal, noon = off, fully counterclockwise = inverted.
  • XFADE CV IN— CV input for controlling crossfade position between parallel and serial folders (±5V).
  • SYM-AUX Attenuverter P— Attenuates DC offset (SYM mode) or AUX input (AUX mode) for the parallel folder. No effect in X mode.
  • XFADE S Input Selector— Selects S-side input for crossfader: FOLD OUT S sends folded output, IN S sends dry input (wet/dry mode).
  • FOLD P CV IN— CV input for controlling folding amount on parallel folder (±10V). Positive voltage increases folding, negative decreases it.
  • FOLD S CV IN— CV input for controlling folding amount on serial folder (±10V). Normalled to FOLD P if unpatched.
  • MIX LED— Indicates signal presence at MIX output. Brightness shows amplitude, color indicates polarity (red=negative, green=positive).
  • XFADE P Input Selector— Selects P-side input for crossfader: FOLD OUT P sends folded output, IN P sends dry input (wet/dry mode).
  • PHASE— Inverts the phase of the serial folder feeding the crossfader, enabling ring modulation and other sonic variations.
  • SYM-X-AUX switch for Parallel Folder— Selects signal source for parallel folder: SYM adds DC offset for symmetry control, AUX mixes AUX input, X disables external modulation.
  • SYM-X-AUX switch for Serial Folder— Selects signal source for serial folder: SYM adds DC offset for symmetry control, AUX mixes AUX input, X disables external modulation.
  • SYM-AUX attenuverter for Parallel Folder— Attenuates DC offset (SYM mode) or AUX input (AUX mode) for the parallel folder. No effect in X mode.
  • SYM-AUX attenuverter for Serial Folder— Attenuates DC offset (SYM mode) or AUX input (AUX mode) for the serial folder. No effect in X mode.
  • XFADE P input selector— Selects P-side input for crossfader: FOLD OUT P sends folded output, IN P sends dry input (wet/dry mode).
  • XFADE S input selector— Selects S-side input for crossfader: FOLD OUT S sends folded output, IN S sends dry input (wet/dry mode).

How-To Guides

  • Basic Single-Source Wavefolding
  • Stereo Wavefold
  • Animated Harmonic Sweep
  • Fold Wet/Dry Blend
  • Ring Modulation
  • Amplitude Modulation
  • Feedback Chaos and Noise
  • Asymmetric Fold Timbre Sculpting
  • Two Oscillator Fold and Blend
  • External Signal Folding Modulation via AUX

Explore the interactive Bifold panel on BleepDex — tap any control to learn what it does.

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