DI Boxes: What Do they Do and Why Might I Need One
All DI boxes have an input (usually a 1/4”), a small transformer, and an XLR output. They also typically have a ground lift toggle switch, a PAD to attenuate your signal and a thru output to send unaffected signal elsewhere.
The primary purpose of a DI box is to convert an unbalanced signal to a balanced signal and eliminate ground hum. A DI box also gives its user the proper impedance to then plug their guitar, bass or keyboard into a mixer for a cleaner, low noise signal.
How Does a DI Box Work - basically
When an unbalanced signal enters a DI box it is sent through an isolation transformer to create a balanced signal. The transformer contains two wire coils around a magnetic metal core. The signal passes from one coil to the other, from the primary side of the transformer to the secondary, to passing a fully isolated signal.
By transferring an isolated signal noisy ground loops are eliminated. This process also takes a high-impedance signal and makes it low-impedance. The transformer has now eliminated noisy ground loops and prepared the impedance of the signal for a standard microphone preamp.
Should I Buy Any Old DI Box?
Honestly, a DI is like a hammer. There are good hammers and bad ones, but if you are just trying to get the job done, a cheap hammer will do it. We bought a $50 DI box and used it to send the Aux out of a older Tube amplifier to a mixing console. It completely eliminated hum that we were experiencing when we wend direct. (The old tube amp was a perfectly functional Wurlitzer 145 tube amp).
Now, that said, basic DI boxes contain one major component (sometimes only one) and that is the transformer. These small isolation transformers can be pricey, so therefor they dictate the price of the box. And, the good ones can actually improve your sound and tone. While a really cheap DI box will get rid of the hum for you, it might lose a little tone.
A DI Box can be a life saver when you are looking to send a signal directly to a mixing board. We reccomend anyone who is recording guitar, bass, keyboards or synth instruments invest in at least one DI box. Experiment with the DI box and see how it cuts down noise for you and improves you recording!
