Leslie C Tyler

US Patent:

43160603, Feb 16, 1982

Filed:

Jan 4, 1980

Appl. No.:

6/109487

Inventors:

Robert W. Adams - Medford MA
Leslie B. Tyler - Newtonville MA

Assignee:

DBX, Inc. - Newton MA

International Classification:

H03J 524

US Classification:

179 1D

Abstract:

An improved equalizing system for modifying an input electrical signal representative of original sound so as to correct for the inherent nonflat frequency response of an audio signal processing apparatus and the acoustic effects of listening environment in which the loudspeaker system of the audio signal processing apparatus may be disposed. The improved equalizing system includes a comparator for comparing the signal energy in each of a plurality of select frequency bands of a predetermined frequency range of the input signal with that of the corresponding signal energy in a like plurality of bands of a like range of a second signal representative of the acoustic output of the loudspeaker system and as a function of the nonflat frequency response and the acoustic effects of the environment. A correction signal representative of the comparison is used to modify the energy within each band of the input signal so as to substantially correct for the nonflat response and the acoustic effects of the environment. In the preferred embodiment, a unique filter arrangement is provided for simultaneously reducing the interaction between adjacent bands and the amount of ripple at the output of the equalizing system.

US Patent:

41829930, Jan 8, 1980

Filed:

Nov 2, 1978

Appl. No.:

5/957307

Inventors:

Leslie B. Tyler - Newtonville MA

Assignee:

DBX Inc. - Newton MA

International Classification:

H03G 310

US Classification:

330279

Abstract:

A system for compressing an electrical input signal so that the output signal is related to the input signal in accordance with a predetermined continuous gain function exhibiting (1) fixed gain where the input signal is below a predetermined set threshold level; (2) infinite compression limiting the output to some predetermined level so that as the input increases beyond a certain input level infinite compression is provided; and (3) a soft threshold between unity gain and infinite compression. The system includes a threshold level adjustment which automatically provides a gain adjustment so that the maximum output level (preferably on an RMS basis) remains unchanged with changes in the threshold level.