Abstract: A dynamic range expander which substantially limits the amount of positive expansion without affecting the amount of negative expansion is disclosed. In one arrangement, gain reduction in the amplitude of the output signal is increased when the amplitude of the input signal decreases toward or becomes less than the noise level present in the input signal. The dynamic range expander includes a detector (24) for sensing the amplitude of the input signal and providing a variable DC signal related to the amplitude of the input signal, a control signal generator (30) and an amplifier (34) for amplifying the input signal by a gain variable responsively to the output of the control signal generator. The control signal generator includes a time averager (50) and a summer (40) for providing a second variable DC signal related to the sum of the detector output and the time averaged detector output.

Abstract: An apparatus having a plurality of time delays for providing simulated reverberation of an electrical signal representative of sound is disclosed. The time delays are chosen so that delay times of initially delayed signals and reflected signals are logarithmically evenly spaced. One arrangement is adapted for driving a plurality of amplifiers of a multiple channel amplifier system by dividing the time delays into a plurality of groups responding to the plurality of amplifiers, and then connecting the groups of time delays to the amplifiers. A different group of time delays can drive each amplifier.