What Are DI Boxes And Why Are They Used in Recording Studios

Audio recording is not just an art but it’s also is a technology that changes frequently. As an audio engineer, you have to be aware of the changes in industry technology and transform yourself with it.

In my article 35+ Recording Studio Equipment List [For All types of Recording Studios] I have discussed almost all the equipment used in the recording studios.

Some of them like audio interfaces. monitors etc are common in all studios, but some are unknown by an average recordings/producer.

DI box is one of them for a bedroom or home studio owner, it’s quite confusing as they don’t know “what are DI boxes and how they are used in recording studios.”

So, this article will tell you what is DI or direct box and why they are used in recording studios.

First off,

What is a DI Box or Direct Box

DI Box

Direct boxes are also known as DI boxes, stand for “Direct Inject” which resolve the basic impedance mismatch between electrodynamic guitar pickups and sensitive studio electronics.

However, most modern DI boxes are far more sophisticated as compared to the older models, the primary function of Direct boxes is to take an unbalanced, high-impedance signal from the instrument and convert that to a balanced, low-impedance signal.

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It allows you to play guitar and bass directly into the preamps without losing volume and by converting into significant high-frequency information.

There are 2 types of DI Boxes

  • Passive DI
  • Active DI

Passive DI Box

In Passive DI boxes typically balun transformer uses in form of a high-impedance signal to a low-impedance signal.

This transformer features electrically separate windings in the input and output stages. That results in both impedance matched for a standard mic pre and free from ground hum originating at the input stage.

Active DI Box

The difference between active and passive DI boxes is an active DI features a preamplifier. This preamp provides the extra gain to boost the weak output of some passive, single-coil pickups. As well as the extra gain is great for driving long cable runs.

Why DIs are Used in Recording Studios

As you know from the above definition, DI boxes are used to high-impedance unbalanced signals to a low-impedance balanced signal, the main function of it in audio recording studios is to provide more clear and more crisp sound.

Also, the balanced version of the signal provides a +4 DB extra headroom that’s a great thing for a good mastering output.

Adding a direct box to your recording studio equipment list is a wise decision because it improves the quality of your audio tracks.

Don’t worry, you don’t need to invest a large amount of money for it. DI boxes are available from just $30 on Amazon.

What to look for in DI boxes

However, there are several DI boxes available on Amazon, you need to be educated yourself on what to look for in a DI box. Here are some features you should look for when going to purchase DI boxes.

Multiple Channels

However, for guitars, a single-channel DI box is sufficient when you need some more inputs for other instruments you can go for two-channel DIs.

You can also go for rack mount DI which has multiple channel inputs. It all depends on your needs and your budget.


If you don’t know here is the definition of thru/bypass. A “thru” (short for throughput) or bypass splits the original incoming instrument signal to a separate 1/4″ output.

So you can route separate unbalanced output for monitoring while balanced one for recording.

Ground Lift

However, DI box is known for reducing or eliminating the external noise, sometimes even balanced audio equipment can make hum and buzz caused by ground loops.

Around lift disconnects the Pin 1 on the XLR jack of the DI box, and prevents the current from flowing between the DI and the microphone preamplifier. That arrangement breaks the ground loop and eliminates this noise.

Pad Switch

A switchable attenuator called a pad is used to prevent excessive gain from overloading the circuitry.

Decreasing the incoming signal by a fixed amount (-15dB and -20dB pads are common) is helpful to control the high output of active pickups.

Polarity Reverse

Sometimes the XLR cables configure Pin 2 hot to Pin 3 hot. In this condition, we need to change the phase switch to reverse the polarity.

Below are the benefits of the phase reverse button.

  • Corrects wrongly wired XLR cables.
  • Aligns the absolute polarity of a direct signal with that of a microphone on the same source.
  • Prevent feedback.

Final words

So, here were the details of DI or direct boxes. I think now you are not confused about this recording equipment. Let me know which one you have decided to buy from Amazon. And don’t forget to share this article with your recording buddies.

Is a DI box necessary for me?

DI box is not necessary gear for a gig, however, it improves sound quality so you can use it as an optional guitar gear.

What 3 things does a DI box do?

DI box does three things to make audio better. First, it converts impedance, second, isolates an instrument, and third, it removes noise bleed from the signal. the combined effects of these three, provide a clean and sweet audio signal.

Can I use a DI box for vocals?

No, a DI box is not ideal for mics. DI box is actually used to convert high impedance guitar signals to line-level signals. Mics already work at line level so you can’t use a DI box with microphones.

Do I need a DI box with an audio interface?

I have already told you above that DI boxes are not the necessary gear, however, you can make your high impedance guitar signal to line level signal which provides you a better signal-to-noise ratio. So, you can use them with audio interfaces.

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Gautam Roy is a recording engineer and a blogger from India. He loves music, writing, and travelling. He is also an active investor and a successful entrepreneur.

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