A DI box can prove invaluable when setting up live performances or studio recording sessions while not changing your sound in any noticeable way. In their most basic form DI boxes will convert high impedance signals, such as a Guitar output, to a low impedance balanced signal. This would allow you to connect a Guitar directly to a microphone input on a mixer and importantly, if the DI box is close to the Guitar, run a long balanced lead back to the mixer without incurring a lot of unwanted noise.
You can also use the DI boxes to connect guitar amplifiers directly to a mixer input. For this purpose many types have a built-in attenuator or level reducer, cutting down the speaker or line level output from the amplifier. The uses for interconnecting equipment are endless and it is a good idea to carry one or two in your “very useful” box, since it is often hard to know what to expect at new venues or when an artist turns up at a studio with a new piece of kit.
A variety of types are on offer from our site, with basic passive single channel types, to multi-channel active boxes. The latter have built-in amplifiers, so can offer a wider range of adjustment if you are trying to match audio levels.
Other applications include isolating electrical circuits, so ground or hum loops do not occur. There are also a number of line isolators shown in this category specifically designed to perform this task. Using a laptop with your PA system will often cause all kinds of unwanted hum and noise, but installing an isolator will often eliminate the problem.