In this video Paul Carlson from Mr Carlson’s Lab tests three different types of capacitor to demonstrate their properties. You need to be careful in audio applications because capacitors can behave like microphones.
Hans Rosenberg runs us through what we should know about resistor noise and how to avoid it. The bottom line is to avoid carbon composition, thick film, carbon film, and metal oxide film; and prefer thin film, metal film, wirewound (watch inductance), and bulk metal foil (expensive but best).
Today I added wirewound to my spell check.
This build uses a W65C265S microcontroller and an old SP0256-AL2 speech synthesizer integrated circuit to add voice output to a circuit.