Attack and Release Time Constants in RMS-Based Feedback Compressors

Attack and Release Time Constants in RMS-Based Feedback Compressors (981k)
By Fred Floru, THAT Corporation
AES Convention Paper 4703, 104th Convention, May, 1998

The goal of the paper is to develop mathematical models for feedback and feedforward compressors. A couple of possible configurations are explored: linear-output RMS detector with linearly-controlled VCA (linear-domain compressor) and logarithmic-output RMS detector with exponentially-controlled VCA (log-domain compressor). It is shown that the transfer functions of both configurations are equivalent. A formula for transforming the compression ratio of a log-domain compressor to that of a linear-domain compressor is derived. The differences between feedforward and feedback compressor configurations, with regard to time constants and performance, are considered.