This project digitally models the Buchla 259 Wavefolder, a nonlinear waveshaping circuit used in West Coast synthesis. The implementation focuses on real-time DSP processing while mitigating aliasing artifacts using the polyBLAMP (band-limited ramp) technique.
This work is based on virtual analog modeling principles and was developed in MATLAB.
The Buchla 259 Wavefolder is an essential component of West Coast synthesis, known for its nonlinear wavefolding that introduces rich harmonic content. This project aims to:
- Digitally model the Buchla 259 circuit while preserving its timbral characteristics
- Analyze the spectral response and minimize aliasing artifacts
- Implement polyBLAMP as an efficient anti-aliasing technique
- Evaluate the digital model against theoretical benchmarks and analog simulations
- MATLAB-based real-time signal processing
- Anti-aliasing using polyBLAMP (Polynomial Band-Limited Step)
- Nonlinear folding via memoryless functions
- Resistor-weighted voltage summation
- Spectral validation via FFT and spectrograms
- Designed for use in virtual modular synthesis and software synthesizers
- Memoryless nonlinear shaping functions based on the methodology of Esqueda et al. (DAFx-17)
- Resistor network emulation with precomputed scalar coefficients
- Fractional delay analysis for sample-accurate alias suppression
- Symmetrical inverse clipping
- Global signal summation with dynamic scaling
- Clone the repository:
git clone https://github.com/annaobara/Buchla-259-Wavefolder.git cd Buchla-259-Wavefolder
📁 docs/ → Final project report (PDF)
📁 src/ → MATLAB implementation files
📁 images/ → Output figures (spectrograms, waveform plots)
📁 tests/ → Example/test scripts
📁 examples/ → Audio demos
The model was tested with sinusoidal inputs. Results showed significantly reduced aliasing and preserved harmonic structures when compared to uncorrected models.
- MATLAB R2022b or later
- Signal Processing Toolbox
Licensed under the MIT License. See LICENSE for details.
Esqueda, F., Pöntynen, H., Välimäki, V., & Parker, J. D. (2017). Virtual Analog Buchla 259 Wavefolder. In Proceedings of the 20th International Conference on Digital Audio Effects (DAFx-17).
Developed by Anna Obara • Aalborg University, 2025