ELEC 3030 Final design project

ELEC 3030Final design project Bass & Treble Control Jordan Lewis & Elizabeth Devore

BASS VS. TREBLE • Bass controls low frequencies around 100 Hz • Used to boost kick drum and bass guitar sounds • Treble controls high frequencies around 12kHz • Used to boost sounds from upper octave piano and flutes

BAXANDALL CIRCUIT • Tone control circuits • Uses resistors and capacitors (or inductors) • Low pass filter (treble-cut), attenuates at high frequencies • High pass filter (bass-cut) attenuates at low frequencies

CIRCUIT LTSPICE DESIGN • After some tinkering….

LOW-FREQUENCY ANALYSIS • Vx ≈ 0 • (Vi) / (RLF1+R1) ≈ (-Vo) / (RLF2+R4) • Av ≈ -(RLF2+R4) / (RLF1+R1) • -20dB < Av < 20dB

HIGH-FREQUENCY ANALYSIS • Vx ≈ 0 • (Vi) / (RHF1+R3) ≈ (-Vo) / (RHF2+R6) • Av ≈ -(RHF2+R6) / (RHF1+R3) • -12dB < Av < 20dB

Mid-Frequency Analysis • R7 = R8 = 1 / (2*π*1000*.1uF) = 1.6k • R9 = 1 / (2*π*1000*.001uF) = 160k • Av = (4.7k+(1.6k||RLF2)) / (4.7k+(1.6k||RLF1)) (-2.5dB < Av < 2.5dB)

SIMULATION IN LT SPICE Treble boost Bass boost Mid-band

THE BIG PICTURE • Bass/treble control circuit placed between detector and audio amp • Large gain

BASS Boost Cut Mid

TREBLE • Unable to view well on the scope at higher frequencies • Gain did not appear larger during simulation, but sounds louder

FINAL THOUGHTS ON DESIGN • Audible change in bass and trebleachieved • Overall, great project!

PART II • Mind-numbingly long and tedious hand calculations….

ELEC 3030 Final design project