Audio filters
Charlie Cullen · Focal Press eBooks · 2020
This chapter introduces first-order audio filters, component networks that vary their amplitude output based on the frequency of the input signal. The chapter begins with a discussion on the frequency-dependent nature of human hearing and also introduces Bode plots that show both the frequency response and phase of a signal. The chapter then covers basic filter characteristics like cutoff and slope and how they change an input audio signal. The chapter will also introduce the equations needed to determine the cutoff frequency of a first-order filter, to design both low- and high-pass filters by swapping the resistor and capacitor around in the divider. The chapter project is a 2-band equalizer that feeds into the LM386 audio amplifier from the previous chapter – a first audio processing circuit.