Connectors and Signal Integrity

Common-mode rejection lets a balanced line run tens of metres near dimmers and motors without audible hum. XLR is the standard connector for balanced microphone and line signals. A TRS jack carries either a balanced mono signal or an unbalanced stereo signal depending on its wiring, and a TS jack is always unbalanced, so TS cables are kept short.

Condenser microphones need power, which travels over the same balanced cable as phantom power. IEC 61938 defines 48 V phantom power (P48) along with 12 V and 24 V variants. A correctly wired balanced dynamic microphone is unaffected, because the same voltage is present on pins 2 and 3. Ribbon microphones are at risk when a cable is miswired or a line is patched while live: Royer Labs reports that the voltage can then reach the ribbon and stretch it, and some vintage ribbons can be damaged by phantom power itself.

Loudspeaker connections carry currents of several amperes instead of the millivolts of a microphone signal. They use locking Speakon connectors, which Neutrik designs for high-current loudspeaker loads and not for microphone or line signals. Speaker-level and line-level connections are never interchangeable, and connecting an amplifier output to a line input can destroy that input. Shielding keeps electromagnetic interference out of the signal, and noise added by a poorly shielded cable cannot be removed later by the console.