AES Warsaw 2015
Tutorial T10
Saturday, May 9, 09:00 — 11:00 (Room: Opera)
T10 - Modern Digital to Analogue Conversion: Audio Alchemy Using Signal Processing
Presenter:Jamie Angus, University of Salford - Salford, Greater Manchester, UK
Abstract:
Almost all modern digital to analogue convertors (DACs) use oversampled multibit convertors with noise-shaping to achieve their high performance. Oversampling and noise-shaping allow one to use a DAC with a small number of levels, which is easier to manufacture. Unfortunately traditional noise shaping does nothing to reduce the effect of component tolerances in the DAC because the analogue output cannot be fed back to the input. However, modern DACs do manage to noise shape the output from the DAC without any feedback. This piece of audio alchemy is critical to the exceptional performance of modern digital-to-analogue convertors. Using audio examples, this tutorial will explain how this alchemy is achieved. It will review the problems of component tolerance in DACs and show how they compromise performance. Then noise-shaping, and how it can be applied, without magic or knowing the actual converted output, to a practical DAC will be explained.
