Digital delay/ambience processor

Abstract

A processor for audio program material which synthesizes simulated reflection and reverberation signals for use in creating the illusion of a specific modeled listening environment. A preferred embodiment of the processor accepts stereophonic audio signals and simulates the multiple reflections of an acoustically modeled environment by recirculating the signals through a pair of digital signal delays which have different delay times. The analog input signals are sampled and converted to digital form by first attenuating the signals with a digitally controlled step attenuator and then encoding the amplitude of the attenuated signal using a ramp comparison technique. The encoded amplitude signals, and a code representative of the attenuator position, are stored in a random access memory and are retrieved after the desired delay. The retrieved digital data are converted back to analog signals by reversing the encoding process, using the same ramp voltage generator. A stack comprised of a counter and two registers connected in a loop generates three addresses during each sample period for use in writing in new data and retrieving previously stored data.