A simple but efficient design of a 5-band parallel graphic equalizer is proposed. One lowpass, one high pass and three bandpass digital Chebyshev type I infinite impulse response filters with given 3-dB points are first designed. With these filters, a 5-band parallel graphic equalizer is implemented. Most graphic equalizers suffer from gain and interaction error. It is shown in this paper that the designed graphic equalizer exhibits gain error of less than 1 dB and therefore satisfies the ±1 dB error tolerance level for audio equalizers. Unlike other equalizer design methods that use linear interpolation techniques, matrix inversion and optimization algorithms to satisfy the ±1 dB error tolerance, the use of the Chebyshev type I filters with given 3-dB points can satisfy this error tolerance. A preliminary test of the proposed equalizer on audio signal and comparisons with existing design methods indicate the promise of the proposed design for audio signal processing applications.
