Download Adaptive Phase Distortion Synthesis This article discusses Phase Distortion synthesis and its application to arbitrary input signals. The main elements that compose the technique are presented. Its similarities to Phase Modulation are discussed and the equivalence between the two techniques is explored. Two alternative methods of distorting the phase of an arbitrary signal are presented. The first is based on the audio-rate modulation of a first-order allpass filter coefficient. The other method relies on a re-casting of the Phase Modulation equation, which leads to a heterodyned form of waveshaping. The relationship of these implementations to the original technique is explored in detail. Complementing the article, a number of examples are discussed, demonstrating the application of the technique as an interesting digital audio effect.
Download Five Variations on a Feedback Theme This is a study on a set of feedback amplitude modulation oscillator equations. It is based on a very simple and inexpensive algorithm which is capable of generating a complex spectrum from a sinusoidal input. We examine the original and five variations on it, discussing the details of each synthesis method. These include the addition of extra delay terms, waveshaping of the feedback signal, further heterodyning and increasing the loop delay. In complement, we provide a software implementation of these algorithms as a practical example of their application and as demonstration of their potential for synthesis instrument design.