DI, Direct Injection Box

A DI unit is an electronic device typically used in recording studios and in sound reinforcement systems to connect a high-impedance, line level, unbalanced output signal to a low-impedance, microphone level, balanced input, usually via an XLR connector and cable. DIs are frequently used to connect an electric guitar or electric bass to a mixing console’s microphone input jack. The DI performs level matching, balancing, and either active buffering or passive impedance matching/impedance bridging to minimize unwanted noise, distortion, and ground loops.

DI boxes are extensively used with professional and semi-professional PA systems, professional sound reinforcement systems and in sound recording studios. Manufacturers produce a wide range of units, from inexpensive, basic, passive units to expensive, sophisticated active units which provide numerous features and user-controllable options and settings and rugged, heavy duty chassis.