Automatic spectral compensation of an audio system operating with a random noise input

A set of 80 filters is used to divide a random noise input spectrum of an audio system into 25 cps increments. An identical set operating as a spectrum analyzer provides a similar function on the system output. By means of an automatic regulating system using solid-state electronics, each of the 80 loops is closed independently, thus providing a unique control system compensating the audio system spectrum and equalizing disturbing resonance phenomena. This method has been successfully applied to the control of a vibration system spectrum where mechanical resonances at the exciter table produce high Q peaks and notches. The degree of spectral flatness reveals that adequate compensation is possible for typical resonance phenomena occurring over a wide frequency range.