Audio interfaces are not only multifunctional, they work magic. Allowing you to connect microphones, instruments, headphones, studio monitors, and plenty of other external audio gear. They convert analog and digital signals, amplify weak ones, all whilst processing and recording high-quality audio.
They are the epicentre of any recording studio. But is an audio interface a DI box? Can they do the same job? In this article I’ll answer your question and explain what a DI box is, what it does, and talk about the practical applications of using one.
Is an Audio Interface a DI Box?
No, an audio interface is not a DI box. Whilst an audio interface also manages the impedance levels of instruments, they cannot split and route instrument signals in the same way that a DI box does. This is why sound engineers use DI boxes in recording studios and during live performances. Whether you need one or not depends on the practical applications explained in this article.
What is a DI Box?
DI stands for Direct Injection. Yikes, that sounds like some kind of horrendous medical procedure. Anyone else here hate needles? Anyway, moving on. A DI dox is a small device that has a very important job to. It converts an unbalanced high-impedance signal from an instrument into a balanced low-impedance signal, like that of a mixing desk or PA speaker.
If you were to try plugging in a guitar or bass directly into a mixing desk or PA speaker, you’d get a lot of unpleasant noise as the levels don’t match. A DI box resolves this issue. That’s not all they do though. They also solve practical problems and have advantages both for recording and live situations.
Why Do I Need a DI Box?
One of the most common uses of a DI box is to split a guitar signal into two. That way you can send a guitar signal to the mixing desk and a guitar amp simultaneously. What’s the point of that? I hear you ask. Great question. The answer is to have more options for mixing.
Let’s say you recorded a guitar amp with a microphone, but the final tone sounded awful. Well, if you used a DI box, no worries. You also recorded a dry signal directly to your mixer and into your DAW.
Now you can disregard that miked amp recording and send the dry signal to either another amplifier -we call this reamping- or to a virtual amp in your DAW.
You’ve given yourself more options to work with. This is a very common practice in recording studios these days. And it makes total sense, right?
Another reason to send a guitar signal to a mixing desk that they have powerful preamps that tend to colour the sound. This is because they contain valves (known as tunes in the US) that add harmonic content to the original signal, affecting the sonic characteristics in a pleasing way.
This can often provide a warm and vintage tone unique to the preamps of that mixing desk. This is usually a desired sound, much like how some guitarists prefer valve amps for the exact same reasons.
For Live Music
In a live setting the application is similar. A sound engineer will use a DI box in order to send an acoustic guitar or bass to the mixing desk, which is then sent to both the performers on stage monitors, and the front of house speakers that the audience will hear.
Or a sound engineer could send this signal to a recording device. That way a live recording can be captured without any noise bleed from the crowd or any other sound sources. Genius. Yes, a DI box is a one of a sound engineer’s best friend in a recording studio or a live setting.
One final application for recording purposes is guitar pedals. Using a lot of guitar pedals results in a hotter signal, which can often be too hot for an audio interface. Bummer, right? Bet you knew deep down that pedal addiction would have its cons. A DI box can help with that with that by converting the signal to a lower impedance one.
Active vs Passive DI Boxes
There are two types of DI boxes, active and passive. Active DI boxes have built-in preamps, which amplify signals louder. Handy if you have a low output guitar for example, like one with single-coils. The downside is that they require extra power (48V) via batteries or a power adapter.
With that extra power, active DI boxes also work wonders for driving long cables. Additionally, they have better headroom, and work really well with instruments that have active pickups. For this reason, they tend to be more expensive than passive DI boxes.
Passive DI boxes require no external power, so you don’t have to worry about batteries running out, or being close to a wall socket. However, they do have an integrated preamp which doesn’t boost the signal, but just does its job of impedance conversion.
Passive DI boxes are more budget friendly. But cheaper ones are less effective at eliminating electrical hums. So, don’t just go for the cheapest one you can find. Buy a semi-decent one.
If you just have a passive guitar or bass, then a passive DI box will suffice. If you’re working with long cables, active instruments, have a higher budget, and prefer something with more power, then buy go for an active DI box.
Do I Need a DI Box with an Audio Interface?
It depends on if the above practical applications apply to you or not. If they don’t and you only need to record a guitar or bass directly into your DAW, then no you don’t need a DI box.
Audio interfaces have specialised inputs for that, which also manage impedance levels. Audio interfaces also work a lot of other magic too. They have special audio drivers, a range of outputs, analog and digital converters, their own preamp, phantom power, plus plenty of other controls and knobs to improve your workflow.
Want to learn more? Be sure to read my article ‘What is an Audio Interface?‘. There’s too much to cover in this article alone.
DI Boxes Provide More Routing Options
DI boxes are a robust, cost-effective tool that really serve multiple purposes for recording and live situations. Buy a well-made one and it should last you a life time. Apart from impedance conversion, they can split instrument signals to give you more options for audio routing.
This is particularly useful during mixing, as you can reamp your bass or guitar recording later. For live situations you can choose to route a DI box’s signals to on-stage monitors or to the front of house speakers, or capture a live band’s performance without noise.
I hope this article answered your question and gave you some insights about why sound engineers use DI boxes. If you’d like to know anything more specific, then please comment down below.