. . "A signal equalizer for adjusting gain in each of first to n.sup.th (where n is an integer of 2 or higher) frequency bands for an initial signal, the circuit comprising: first to n.sup.th extraction circuits that are provided in correspondingfashion to the first to n.sup.th frequency bands and that extract and output a corresponding frequency band component of the initial signal, first to n.sup.th" . .