In the quest for perfect tone, many musicians have found all-tube amplifiers to be an ideal fit. After all, nothing compares to the heft, warmth, and richness of a good tube amp. However, there is one glaring drawback - weight. All those tubes and heavy transformers really add up to take a toll on your back. Spend a few months or even a few weeks moving a heavy tube amp up stairs or squeezing it into the back of a packed van and you’ll likely start to wonder if the tone is worth it, or if a similar tone is available in a more portable package.
When the sound tech needs to connect an instrument-level source (such as a bass guitar or keyboard) to the PA system, they will typically reach for a direct injection box (DI box). At first thought, this might seem counter-intuitive, since most mixers have 1/4" inputs and enough gain to match a wide range of signal levels. So, what are DI boxes, and why are they used?