EE4435 Fall 2002Design Project 1A Gr a ph ic Eq u alize rObjectThe object of this experiment is to design, implem ent, and test a three-band octa ve graphicequalizer .BackgroundDevices that are used to alter the frequency response of an audio system are called equalizers.Thetwotypesofequalizersthataremostcommonlyusedaregraphicequalizersandpara-metric equalizers. The graphic equalizer has controls whic h can be used to boost or cut theresponse of the system at fixed frequen cies. The frequencies of ma ximum boost and cut inthe graphic equalizers that are used in most professional applications are spaced one-third ofan octa ve apart. That is, the ratio of two adjacent frequencies is 21/3. In equalizers designedfor the consumer market, octav e equalizers are more common where the spacing bet ween thefrequ en cies is 2. The frequencies are normally c hosen so that 1 kHz is one of the frequencies.A ten-band octave equalizer w ould ha ve the frequencies 31.25 Hz, 62.5 Hz, 125 Hz, 250 Hz,500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz.In a parametric equalizer, the boost/cut frequencies are adjustable. In addition the band-widths of the filters are adjustable. For most professiona l application s, a three-band para-metric equa lizer is adequate.This experimen t involv es the design of an octave graphic equalizer having only three bands.Addition al bands can be added if desired, but the design principles can be demonstratedwith only three bands.Th e Ba sic Filter To pologyThe paper “Design Aspects of Graphic Equalizers” b y R. A. Greiner and M ichael Sc hoesso wthat is on the class web page reviews several topologies for graph ic equalizer circuits. Youare to read this paper and select a circuit from it. The text for the class also discusses apossible circuit in Chapter 3. Ho wev er, this circuit is based on the one published in theposted paper.Specifications• The boost/cut frequ encies are to be 500 Hz, 1 kH z, and 2 kHz. If y ou desire, y oucan add more octave spaced frequencies to y o ur circuit, but only three are required tocomplete the lab.• The circuit is to be designed so that the voltage gain is unit y w ith the equalizer con t rolsset at zero boost/cut.• Wh en an y one of the three contr ols is set for maximum boost, the gain at that frequencyis to be 4, i.e. +12 dB.• W hen any one of the three con tro ls is set for maximum cut, the gain at that frequencyis to be 0.25, i.e. −12 dB.1• Thedcoffset at the output of the circuit is to be less than 10 mV.• Ahigh-passfilte r is to be incorporated at the inpu t of the circuit to block the appli-cation of any dc input voltage. The lo wer cutoff frequency of this filter is to be 2 Hzor lower.Sc hedule• You should read the paper and select a filter topology befo re the first lab meeting.• During the first lab period, you should successfully realize the circuit with the 1 kHzfilter. You should v erify your design before assem b ling the circuit with a SP IC E sim-ulation.• Durin g the second lab period, yo u should successfully add the 500 Hz and 2 kHz filters.• Durin g the third lab period, y ou should test and documen t the perform an ce of thecircuit. You should tak e sufficient data to show how the filters interact when one ormore are set in the boost and/or cut modes.• Your lab report should include all calculations, measured data, and SPICE