Editing DI unit (section)

{{Short description|Audio signal conversion device}}
{{refimprove|date=January 2018}}
[[File:DI Box 8121.jpg|thumb|right|A professional passive DI box. It is ''passive'' because it does not need external power to operate. DI boxes which require a power source (batteries or [[phantom power]]) are called ''active'' DI boxes.]]

A '''DI unit''' (direct input or direct inject) is an electronic device typically used in [[recording studio]]s and in [[sound reinforcement system]]s to connect a high [[output impedance]] unbalanced output signal to a low-impedance, microphone level, [[Balanced audio|balanced]] input, usually via an [[XLR connector]] and XLR cable. DIs are frequently used to connect an [[electric guitar]] or [[bass guitar|electric bass]] to a [[mixing console]]'s microphone input jack. Its signal comes "direct" from the source instrument without passing through the air as [[sound wave]]s, and thus is isolated from other sounds and avoids effects of [[microphone]] or [[room acoustics]]. The DI performs level matching,{{cn|date=September 2023}} balancing, and either active [[buffer amplifier|buffering]] or passive [[impedance matching]] or [[impedance bridging]]. DI units are typically metal boxes with input and output jacks and, for more expensive units, “ground lift” and attenuator switches.

DI boxes are extensively used with professional and semi-professional [[PA system]]s, professional [[sound reinforcement system]]s and in [[sound recording]] studios. Manufacturers produce a wide range of units, from inexpensive, basic, passive units to expensive, sophisticated, active units. DI boxes may provide numerous features and user-controllable options (e.g., a user-selectable 0dB, 20dB or 40dB [[Attenuator (electronics)|pad]] and/or a "[[ground lift]]" switch). They may come in different types of enclosures, usually a metal chassis that helps to protect against electrical interference.  Some [[bass amplifier]]s have built-in DI units, so that the bass amp's output signal can be connected directly to a mixing board in a sound reinforcement/live show or recording context.