Download Modeling and Extending the Rca Mark Ii Sound Effects Filter We have analyzed the Sound Effects Filter from the one-of-a-kind RCA Mark II sound synthesizer and modeled it as a Wave Digital Filter using the Faust language, to make this once exclusive device widely available. By studying the original schematics and measurements of the device, we discovered several circuit modifications. Building on these, we proposed a number of extensions to the circuit which increase its usefulness in music production.
Download Antialiasing Piecewise Polynomial Waveshapers Memoryless waveshapers are commonly used in audio signal processing. In discrete time, they suffer from well-known aliasing artifacts. We present a method for applying antiderivative antialising (ADAA), which mitigates aliasing, to any waveshaping function that can be represented as a piecewise polynomial. Specifically, we treat the special case of a piecewise linear waveshaper. Furthermore, we introduce a method for for replacing the sharp corners and jump discontinuities in any piecewise linear waveshaper with smoothed polynomial approximations, whose derivatives match the adjacent line segments up to a specified order. This piecewise polynomial can again be antialiased as a special case of the general piecewise polynomial. Especially when combined with light oversampling, these techniques are effective at reducing aliasing and the proposed method for rounding corners in piecewise linear waveshapers can also create more “realistic” analog-style waveshapers than standard piecewise linear functions.