impedance

Impedance is series resistance for AC signals¹. In a guitar rig, it matters at inputs and outputs: buffers take a high impedance signal and convert it to a low impedance one², and a low output impedance lets a pedal run long signal chains³. Input impedance affects tone and interaction, as with wah pedals whose input impedance adjustment produces a warmer, more powerful tone⁴, and fuzzes that are picky about the guitar pickup feeding them⁵. Some pedals expose impedance as a control, changing how pickups respond⁶ or shifting a fuzz between overdrive-like and fuzz sounds⁷.