Circuit arrangements for modifying dynamic range using series and parallel circuit techniques

摘要

The circuit arrangements for modifying the dynamic range of signals, particularly compressors and expanders for use in noise reduction compander systems, have the advantages of fixed band characteristics (variable attenuation throughout all or part of the frequency band) and sliding band characteristics (variable attenuation through part of the frequency band achieved by a variable pass filter), without the disadvantages normally inherent in each characteristic. Fixed band and sliding band compressors (54, 56) are operated in parallel, as are complementary expanders (60, 62), the compressors and expanders operating in generally the same level range and at least a partial overlapping in frequency range. The transfer characteristics of the parallel circuits add. Alternatively the circuits are operated in series and their characteristics multiply.