ABSTRACT
This chapter discusses DI (Direct Injection) boxes as an essential and too often underestimated component of any live sound rig. There are two main types of DI box: passive, transformer based models and active electronic types. DI an acoustic instruments pickup won't eliminate the risk of feedback altogether, but certainly be able to get more level before feedback than when using a microphone. The piezo crystal-based pickups found on many acoustic instruments require a particularly high-input impedance to work correctly. With suitable wiring, the input accepts an unbalanced source, and the output is balanced. If the ground-lift switch is opened on a DI box, there is no direct ground connection between the source and the mixing console. Noise does occur in poorly designed computers and audio interfaces. If running on battery power doesn't cure the noise, should try running the audio from the computers headphone jack rather than from an external audio interface.
