Editing DI unit (section)

==Preamplifiers==
A number of companies make combination [[preamplifier]]-DI units for [[electric bass]], [[double bass]], or for acoustic instruments which use piezoelectric pickups (e.g., a violin, acoustic guitar, mandolin, etc.). These units may be housed in a "stompbox" pedal format, in a small rackmount unit (often less than a full rack space), or in units designed to be clipped to a belt or attached to an instrument.

Preamplifiers for electric bass typically contain gain knobs, sometimes including an [[fuzz bass|overdrive]] [[effect unit]], equalizer knobs and, for some higher-end units, multiple channels (e.g., a "clean" channel and a "dirty" channel, with the latter containing an overdrive effect). 

Preamp-DI units for double bass and other acoustic instruments often omit the overdrive features, but add additional features that help to produce a good sound and tone for acoustic instruments, such as an [[Dynamic range compression|audio compression]] effect, a phase inverter switch and a notch filter (the latter two features designed to help reduce unwanted [[audio feedback]] "howls"). Preamp-DIs for acoustic instruments often include two channels and a simple mixer, to enable the player to use both a pickup and a [[condensor microphone]]. Some preamp-DIs provide [[phantom power]], in case this is required to power a condenser microphone. Preamp-DI units may be battery powered, have an [[AC mains]] plug, or both.