How I Use DI Boxes

DI boxes are pretty useful little devices. If you never used one or don’t know what they do, you are at least one step behind getting a pro-level sound out of your instrument. This article aims at filling that gap.

In my opinion, a high quality DI box is one of the most important pedals a gigging musician should have.

What is a DI box?

Basically, a DI box transforms your 1/4″ jack to an XLR output. Typically, a DI box also has a parallel 1/4″ output as well. Therefore, you can plug your instrument into the DI box and have get an unbalanced (1/4″) and balanced (XLR) output.

Now, why is this important? Why do sound guys insist that you plug into a DI box; instead of running your 1/4″ jack into the mixer or connecting your amp to the mixer?

DI on the stage

A typical stage setup is like this:

• You plug your instrument into the DI box
• XLR output goes into the mixer
• Line output goes to the amp

That’s the setup that most sound engineers will want, and for good reasons too.

Long unbalanced 1/4″ cables may cause signal loss, and you end up with a bad tone. Balanced XLR cables preserve the signal much better. That’s something that a DI box does for you: Converting & protecting your tone.

A good DI transformer (such as Jensen) will prevent ground loops; which can protect you from hum problems in many cases. Only high quality DI boxes have such transformers. (Note: XLR output of your preamp pedal / amp / cheap DI might lack such a transformer).

Stage-sound typically differs from outside-sound. If you run from the amp to the mixer, any change you do on the amp can unintentionally ruin the sound outside. Using a DI box, you always send your neutral signal to the mixer, and your knob twists only change the stage-sound.

A DI also prevents the risk of a potential amp failure. When you go into DI, your signal keeps going to the mixer even if you blow up your amp.

DI in the studio

On top of all the advantages mentioned above, using a DI box in the studio also enables multi-track recording.

With help of DI boxes, I provide two signals to the sound engineer when recording:

• A strictly dry bass signal
• Same signal running through my effect pedals

That enables the sound engineer to blend / reamp / duplicate / etc the dry signal as needed. If he likes my effects in the mix he can keep them; otherwise, he can simply use the dry signal through alternative effects or settings.

Which DI box

You will see two kinds of DI boxes: Passive and active.

Passive DI boxes have no power requirements and can be used anywhere, anytime. The down side is; it can eat the high frequencies if you plug a high impedance passive instrument (such as an electric guitar or passive bass).

Active DI boxes need 48V phantom power from the mixer, but they preserve the top end of passive instruments better. Downside is; they don’t work if you can’t get phantom power for some reason (typical case: inadequate backlines).

A general recommendation (not rule) is;

• If you have a passive instrument, you either get an active DI box, or a passive DI box + a buffered pedal beforehand (boost, compressor, EQ, etc)
• If you have an active instrument, you get a passive DI. An active DI works too, but no need to risk the “no phantom power” case.

In terms of brands, my personal experience with Radial has been very satisfying. Not all of their products have ground-loop-preventing Jensen transformers though. If you have the money, I recommend getting one with Jensen transformers.

As far as I know;

• JDI is their flagship passive DI (with Jensen)
• J48 is their flagship active DI