DI (Direct Input)
Definition
A direct injection box that converts a high-impedance, unbalanced instrument signal (such as electric guitar or bass) to a low-impedance, balanced line-level signal suitable for recording directly to a console or audio interface, bypassing a microphone and speaker.
In Simple Terms
A box that lets you plug an electric guitar or bass directly into your recording setup, bypassing an amplifier. You get a clean, pure signal that you can process later however you want — real amp or plugin amp.
In Practice
A bass guitar is recorded both through a DI box and through a microphone in front of the cabinet. The DI provides a clean, phase-coherent signal while the mic captures the speaker's character — both are combined in the mix.