An equalizer circuit is disclosed having adjustable bandpass filters connected with operational amplifiers in feedforward and feedback paths so as to form frequency selective boost and cut signal components, which are then combined to form the equalized output signal by a subtractive operation with a direct unfiltered signal path arranged in parallel with the filtered feedforward and feedback paths. The circuit exhibits a constant-Q operation in that it can be adjusted for selected frequency boost and cut without distortion of the component bandwidths of the individual filters.