8.12 Audio beyond the amplifier

Outcome 12 of 12 in domain 8 · Systems, reading and designing a complete device

The loudspeaker, the enclosure and digital audio.

My targets

I declare:

Explain the loudspeaker: impedance (and why "8 Ω" isn’t one), resonance, power handling, sensitivity in dB/W/m.
Measure a loudspeaker’s impedance curve and derive its resonant frequency.
Explain enclosure types (sealed, bass-reflex) and calculate a simple volume from the driver’s parameters.
Design a two-way passive crossover (woofer, tweeter) and measure it.
Explain the digital chain: sampling, resolution, I²S, digital-to-analog converter, codec; get clean sound out of a microcontroller or a Raspberry Pi.
Measure an audio chain’s noise and distortion with a sound card and free software.
Diagnosis: missing bass or harsh treble on a home-made speaker, crossover, phase between drivers or enclosure volume; the measurement that decides.