Audio
DI Box (Direct Injection)
01 — Definition
A box that converts an unbalanced, high-impedance instrument or line signal into a balanced, low-impedance mic-level signal a console can take over a long cable. Passive DIs use a transformer — no power, bomb-proof, ideal on hot pickups; active DIs use a powered circuit (phantom or battery) for higher input impedance and level, and do better on passive instruments. A ground-lift switch breaks the ground loop that causes hum.
02 — In the field
Reach for a DI to send a keyboard, a guitar or a laptop output down a long snake without hum or loss of top end. Flip the ground-lift if you get a buzz when the instrument and the console share two ground paths.