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.
