8.4 The interfaces between stages

I declare: solidlikelyshaky

1. Explain output impedance and input impedance, and the rule of ten so the next stage doesn’t load the previous one.
2. Know the standard levels (mic, instrument, consumer and pro line, speaker) and what each transition requires.
3. Explain capacitor coupling and direct coupling, what each passes and what it costs in bass or in drift.
4. Draw a device’s grounds (star, plane, chassis) and explain the ground loop and the hum it makes.
5. Explain what a stage’s feedback does to its impedances, and why the op-amp seems not to load.
6. Diagnosis: missing bass or a level that collapses when you connect the next stage, too heavy a load or too small a coupling capacitor; the calculation and the measurement.