Fifty shades of distortion
Ivan Cohen, Freelance Software Developer & Owner, Musical Entropy
‘Distortion’ is a word we hear a lot in audio and DSP areas. Historically, it is associated with "nonlinear distortion" (NLD), and we talk a lot nowadays about the "saturation" of high-gain guitar amplifiers, "fuzz" and "overdride" pedals, audio effects such as dynamics compressors, exciters, tape recorders and transformers simulations... But we use also that word for the phase response of some textbook IIR filters, for "spatial distortion" meaning changes related with multi-channels audio streams. Distortion exists in a lot of contexts with different meanings and origins, like bias distortion, crossover, granular, group delay distortions, bitcrushing, hysteresis, chaos, aliasing, frequency-warping, clipping, slew rate, glitches, inter-peak clipping and even programming bugs ! In this talk, you will listen to a song which has been designed to exhibit around fifty different kinds of distortion, and we will study most of them, to understand better why some of these algorithms feature the so-called "analog warmth". You will learn some basic principles of analog modeling, how to bring some life in your classic waveshapers, using the features of the new DSP module, and you will discover how to code original audio effects based on unknown before kinds of distortion.
Presented at ADC 2017, Code Node, London.