Distortion-cancellation circuit for audio peak limiting

DETAILED DESCRIPTION I claim: 1.
In an audio peak limiting apparatus, an improvement for reducing distortion comprising: a clipper coupled to receive an input audio signal; a differencing means coupled to receive said input audio signal and the output of said clipper, for providing a signal representative of the clippings from said input audio signal; a band-pass filter coupled to said output of said clipper; a voltage-controlled amplifier for amplifying low-frequencies in said input audio signal; control signal generation means coupled to said differencing means for generating a control signal for said amplifier, said control signal representing a direct current level and low-frequency spectral energy in said signal representative of said clippings, said control signal coupled to said amplifier such that less amplification occurs as said low-frequency spectral energy increases; combining means for combining the outputs of said band-pass filter and said amplifier to provide an output signal.
2.
The improvement defined by claim 1 wherein said control signal generation means includes a rectifier for rectifying said signal representation of said clippings.
3.
The improvement defined by claim 2 wherein said band-pass filter comprises a first low-pass filter and a second low-pass filter, said first low-pass filter having a cut-off frequency higher than the cut-off frequency of said second low-pass filter, the difference in cut-off frequencies between said first low-pass filter and second low-pass filter defining a band-pass, and where the output of second low-pass filter is subtracted from the output of said first low-pass filter in said combining means.
4.
The improvement defined by claim 3 wherein said input audio signal is coupled to said amplifier through a third low-pass filter, said second and third filters having identical characteristics.
5.
The improvement defined by claim 4 wherein said cut-off frequency of said first low-pass filter is approximately 15 kHz, and said cut-off frequency of said second and third low-pass filters is approximately 2