Projeto e análise de um equalizador gráfico de três bandas

Abstract

This work presents the project and analysis of a three band graphic equalizer in terms of gain, phase and group delay. An analysis of the phase variation is done for a frequency range (from 10 Hz to 20 kHz) and for determined gain configurations of the equalizer. The project and analysis of these parameters are important. Considering that the equalizers are largely used in audio applications, it is necessary to be attentive to the suitable features regarding the band, the gain, the phase and possible distortions. The studied circuit does not utilize inductors, since these were substituted by gyrators, which simulate inductors. The equalizer analysis is done from nine work situations, from when it operates in 100 % of gain in the desired bands – in other words, bass, medium or treble – to when it is 0 % or 50 % of gain from the potentiometers intended to this adjustment. Comparisons between the circuit simulation done by the software PSPICE and GNU Octave and the data experimentally collected were done. From the comparisons it was possible to analyze if the data empirically collected were fitting and coherent to the simulated. Then, it was checked in which situations interference in the project would happen and, because of it, it was analysed in which of those it would be viable to have as a result a suitable signal in terms of phase distortion. Finally, the project presented satisfactory results, presenting a good approximation between the experimental and the simulated results. It was verified that the best situation to the operation of low distortion bands would be when one was working with half gain from the potentiometer.