What Is An Audio Interface And Why You Need One

What Is An Audio Interface And Why You Need One What Is An Audio Interface And Why You Need One

You’re getting ready to dive into creating your own music. You’ve read an entire internet’s worth of information about DAWs, plug-ins, and software instruments. You’re fired up! Then you read a little more on studio equipment and face a daunting question: what is an audio interface? Something else to buy? Maybe, maybe not.

In this article we'll be covering what audio interfaces are; how they work; how they differ from sound cards; the various audio interface connection types available; whether you need a dedicated audio interface; how to connect it to your computer; and last, but by no means least, which of the many audio interfaces you should buy. For those of you who just like to skim articles (you know who you are...) there'll also be an FAQ section at the end. Read on to get the low down…

What is an Audio Interface?

In the simplest terms, an audio interface is a device that connects to your computer and enables you to get audio in and out of it. Every computer has an audio interface (sometimes referred to as a sound card); that’s how you hear a ding every time a cute dog video gets posted on YouTube. It’s also how people can listen to you when you’re talking on a Zoom call – through the mic that captures the sound. But the sound card inside your computer was designed  for personal use, not for production quality audio, and thus began the rise of the external audio interface.

To get a little more technical, these magical little boxes take analog signals and convert them into digital audio that your DAW software can understand. It also does the same process in reverse, so you can play back your recording on external monitor speakers.

Most audio interfaces include line level inputs and outputs, and microphone preamps. Additional features can include digital outputs and inputs, midi ins/outs, and 'combo connectors'; inputs that allow either XLR or 1/4" connection.

How Does An Audio Interface Work? (What’s in an Audio Interface?)

A quick search for audio interfaces will show you just how many varieties are on the market, all with different specs and configurations. Confusing, right? Luckily, they are all essentially born of the same mold.

Inputs & Outputs

Inputs will allow you to record using ¼ inch instrument cables (for instruments) and XLR cables (for microphones). How many inputs your audio interface has will dictate how many tracks you can record simultaneously.

For example, a singer-songwriter may want to record a vocal take and an acoustic guitar simultaneously. So a simple two-in/two-out audio interface will be sufficient for the project. Someone who wants to record a fully mic’d drum set-up for remote session work will need more inputs.

Outputs will allow you to connect external speakers, ideally studio monitors, with a flat response to paint an accurate picture of how your music sounds. Some interfaces have multiple output options, for instance, when mixing in surround sound or sending audio to different destinations simultaneously. Think about how many outputs you need when choosing an audio interface.

Many manufacturers offer different versions of the same type of audio interface. Most of the time, the differences depend on the number of inputs and outputs each one provides.

Inputs and outputs will each have separate controls for their respective levels, so you can adjust the input signal of your overly-zealous (read: loud) guitarist with ease.

Mic Preamps

Welcome to the audio science laboratory part. This post isn’t the place to go into a lot of detail. All you need to know is that a mic preamp contains circuits that boost a low-level mic or instrument to get it up to line level. The preamp quality affects the quality of the audio you record. Remember the adage ‘garbage in, garbage out?’ Some audio interfaces boast ultra-high quality mic preamps and come with a price tag to match. Luckily for your bank account, there is a range of affordable audio interface options with great preamps. One point to team technology.

Something you'll want to consider when choosing an audio interface is phantom power. This is not a Star Wars prequel, it's a 48 volt signal that condenser microphones need to work. If you only record with a dynamic mic you won't need this, but if you use, or plan on using a condenser microphone, you'll need a 48v Phantom Power switch on your interface.

Audio Converters

Continuing our foray into the audio science laboratory… You’ll need to get your audio from the analog world into the digital realm. Your audio interface will convert the signal into something your computer can read by turning it into thousands of tiny samples during this process. The same process occurs the other way; digital audio is converted back to an analog signal and piped to your speakers.

This is where sample rates and bit depth come into play; the higher the sample rate and bit depth, the better the quality of the audio (and the resulting file will also be larger!). And so, the better quality your converters are, the better quality your audio recordings will be.

As technology marches ever-forward, so does the capacity for audio interfaces to support increasingly higher sample rates and bit depths. Some go up to 24 bit/192kHz, which could be seen as overkill, when you consider that CDs and streaming services like Spotify use 16bit/44kHz. So, for a small project studio, an audio interface that supports up to 48kHz will do the job just fine.

Monitoring

When you’re recording, you’ll want to monitor what’s happening, and every audio interface will have a dedicated section for precisely that. On basic interfaces this will be a volume knob for the cue output (generally, you’ll be using headphones) and a knob to control the mix between the input and output. Say, for instance, you’re recording a vocalist topline to a track you’ve created; the vocalist will want a blend of their voice as well as the music. The mix knob will control just that.

Latency

Latency? Think about the journey your audio has to make:

  • Converted in your interface from analog to digital
  • Sent from your interface into your computer
  • Processed by your DAW (with effects, playing back with the the rest of the track, etc.)
  • Back from your computer to your audio interface
  • Finally, converted back from digital to analog

It's a wonder that all of this only takes a fraction of a second to happen, but it's noticeable, and is a huge distraction for vocalists and instrumentalists alike. The best way to counteract excessive latency is by reducing the buffer size in your DAW. The buffer controls how much time your computer is allowed to process all the audio. Smaller numbers equal lower latency, but it puts a bigger strain on your systems processing power, resulting in pops, dropouts, and sometimes your recording software falling over.

Having more CPU power can help counteract this, but some audio interfaces offer direct monitoring (sometimes called zero latency monitoring) which tackles pesky latency head on without impacting the performance of your computer.

By sending a copy of your (pre-computer) audio signal directly to the headphone output you get to hear what you're doing in real time. More sophisticated audio interfaces have a control that lets you choose how much of the direct sound you hear compared to the processed (computer) sound.

‍MIDI Connection

Some audio interfaces will also offer MIDI In/Out connection to external  devices. This is super handy if  you don’t have enough ports on your computer to handle a dedicated MIDI interface.

You can connect a midi keyboard or other midi controller to play your software instruments using the MIDI in connection. The MIDI out connection allows you to hook up an external device (like a keyboard workstation, or synth) and have the MIDI from your DAW 'play' that instrument.

Insert Connections

The ability to use insert effects on an incoming audio signal can assist with tasks like adding a little light compression as you record a vocal. Some audio interfaces offer this option.

Drivers

Drivers are the natty little bits of software that make your audio interface run on your set up, and help deal with latency to the point where you don't notice it. Latency is the delay between the audio being sent to your computer,

What's The Difference Between an Audio Interface and a Sound Card?

This sounds like it could be the set up for a Mac/PC joke, but it's actually a great question. Essentially a sound card and an audio interface do the same job - converting analog signals to digital and back again. But sound cards are mounted internally, and audio interfaces are external. Additionally audio interfaces provide more control over the sound quality by offering things like line level analog inputs, XLR inputs, phantom power for your condenser microphone, and the ability to record multiple instruments at the same time.

Types of Audio Interfaces

Audio interfaces connect with your computer the same way other peripherals do; via ports on your computer.

USB

USB audio interfaces are suited to podcasters, and solo artists/composers who generally only need to record one source at a time, and hear what's coming out of their DAW.

Firewire/Thunderbolt

The beefier cousins to usb, firewire and thunderbolt audio interfaces  will tend to have more input and output options, and can be better at handling latency due to higher signal bandwidth.

Which is the Right Audio Interface?

Whether you choose a USB, Firewire or Thunderbolt audio interface will depend on your computer’s ports and how you’ll use it. If you’re planning on recording multiple channels simultaneously (a full drum kit, for example), you’ll want to choose a connector with higher bandwidth, such as Firewire or Thunderbolt. If it’s just you crooning away to your masterpiece, then USB will be ample.

Do I need an Audio Interface?

The answer to this question varies, depending on how you make music, and to some extent, what kind of music you make. If, for example, you work exclusively in EDM, and everything you create is purely sample and software instrument-driven (and you’re comfortable working only with headphone mixes), then the stereo output from the built-in sound card that came with your computer will suffice.

It's a different matter if your music production adventures involve audio recording. Say you’re a singer-songwriter and plan to record vocals using a microphone, or you want to dust off your trusty old Fender Strat to shred out a riff, you’ll need a way to get that sound into your computer. If you want to record both at the same time, you’ll need two inputs in order to record separate tracks.

Similarly, if you want to save your ears from fatigue or annoy the neighbors by hooking up some external speakers, you’ll need a way to get sound out of the digital realm and into wall-shaking territory. Bring on the audio interface.

‍How To Connect An Audio Interface To Your Computer

This is usually a simple task, but computers being computers things can go sideways occasionally if steps are done in the wrong order. To save yourself grief and gnashing of teeth, follow this step by step guide:

  1. Quit all applications
  2. Make a back up of your system (you do that regularly anyway, right?)
  3. Restart your system (maybe not entirely necessary, but it gives your 'pooter a fresh slate)
  4. Connect your interface to your Mac/PC with the appropriate connection. If you have more than one option, go for the one with the highest bandwidth.
  5. Install any drivers that are required. Normally this is automatic, but you may need to download the latest driver from the manufacturers website.
  6. Make sure your monitors/speakers are off. Connect them to the main stereo output of the interface.
  7. Launch your DAW or recording software. Specify the input and output of the software to route to your new shiny piece of audio gear.
  8. See if it works! Play back that last masterpiece you worked on, then...
  9. Hook up your mics and/or instruments to the inputs on the interface.
  10. Test the input signal by recording something through each channel.
  11. Celebrate with a dance. I recommend a dabbing, but be wary of mic stands or sintruments in close proximity.

Great, but which audio interface should I buy?

The market has audio interfaces to match every budget, from sub-$100 to multiple thousands of your hard-earned cash. Be realistic about what you’re planning to do audio-wise. Do you need eight In/Out if it’s just you and your uke when a two In/Out will do? On the other hand, if you’re pretty sure that next year you’ll be recording some live sessions with your Cajon/flute/sitar jam trio, then a four In/Out will allow room for growth.

The other factor to bear in mind is progress. Ports become obsolete, operating systems move on, and technology improves the performance of devices. Expect to get around 5-7 years of use from your audio interface before the incompatibility gremlins come knocking (firewire ports, anyone?).

Figure out what you need from an audio interface, set your budget, and do your research.

Happy recording!

Audio Interface FAQs

For all you skimmers, and the hardy souls who have read all the way through, here's answers to some common questions about all things interfacey...

Is a mixer an audio interface?

It can be. Some mixers do have the capability to connect with a computer, but these will specifically say that they are both a mixer and an audio interface. An example is the Behringer Xenyx Q502

Is an audio interface worth it?

If you want to record production quality audio then most definitely. Yes, there are stories about people recording a vocal on an iPhone and using that capture to produce a track. But at some point in your musical journey you'll probably want to consider investing in an interface. And entry level models are designed specifically not to break the bank.

Do I need an audio interface if I'm not recording?

If all your music is software based, and you're an expert at mixing on headphones, then technically you don't need one. But if you want to hear what your latest slapping tune sounds like on monitors you'll need an audio interface with speaker outputs.

What are the outputs on an audio interface for?

On the simplest models, these outputs are used to connect with studio monitors so you can hear what you're working on. As you step up the audio food chain you may have more options, for instance to send a signal to a set of speakers in a separate monitoring booth, or to outboard gear for external processing.

Can you connect an audio interface to a TV?

Technically you could connect the output of your television to an input on your interface. But then again, why would you? Stop watching TV and make some music!

Can an audio interface be connected to phone?

A few of years ago the answer would have been no. But nowadays there are many dedicated interfaces that connect with iPads and iPhones. Android users have less options, but there are still some available, like the IK Multimedia iRig PRO I/O

Can you use a DAW without an audio interface?

Absolutely! You can use the headphone socket on your laptop or Mac/PC to monitor what you're doing. If you need to record external sources you can use a USB microphone to do so. And nearly all dedicated midi controllers can connect directly with your DAW via a USB port.

Can you use an amp as an audio interface?

I'm going to say no, because at the moment you can't. But who knows what the future holds? Perhaps in a few years there'll be an amp that can also talk with your DAW and handle multiple input channels.

What can I use instead of an audio interface?

To listen to the output of your DAW, you can simply use the built in output on your computer, although I highly recommend using headphones rather than relying on the internal speakers. To record external audio consider using a USB mic - there's some great ones out there, like the Rhode NT-USB Condenser mic.

Does an interface affect sound quality?

In a word, yes. Both in and out. Even the simplest interface will be a big improvement on your computers internal sound card. The bigger the price tag (generally) the better the mic preamps and converters for turning your analog signal into digital audio, and vice versa, and so the better the sound quality.

What is the difference between a cheap and an expensive audio interface?

Firstly, let's say 'budget friendly' rather than cheap... Lower end models will have less input and output options, and record at lower sample rates. They also might not have  balanced line inputs (which can result in annoying ground loops), or zero latency monitoring. More expensive interfaces will be more geared towards professional recording, so can record multiple intruments at the same time, may include an onboard dsp or two, or have the option for software mixing before reaching your DAW.

Are Universal Audio interfaces worth it?

Universal Audio interfaces arguably have superior sound quality when it comes to converting audio into the digital realm. They also come with a whole suite of plugins to process that pristine audio you just captured, which is definitely a bonus if you're just starting out in production and don't have a large arsenal at your disposal.

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