What is an Audio interface, and Do I Need One?

An audio interface is a device that brings audio in and out of your computer. It takes the audio signal from a microphone or an instrument and converts it into digital audio that can be read by and stored on your computer.

At the same time, it’s also able to convert your digital audio from your computer into an analogue signal which can be heard using your speakers or headphones.

This digital audio can be from music that you have recorded, or playback from a streaming service, or anything on your computer that produces sound.

You may have seen the phrase “soundcard” before when referring to computer audio, which is essentially another name for an audio interface. Whereas “soundcards” are traditionally built into a computer, you can think of an audio interface as an external sound card, normally connected through USB or Thunderbolt.

There are some key reasons why you would benefit from using an audio interface:

The three most common styles of microphones are dynamic, condenser, and ribbon mics. These capture sound in different ways from one another and therefore have slightly different characteristics.

While the audio on computers, cameras, phones, and tablets are getting better each year, it is understandably often not a priority. An audio interface is specifically designed to give you high-quality audio in and out of your device, so you should get an improved audio quality over using your built-in sound cards.

You’d actually be surprised at how much difference there can be listening to a song on headphones coming directly out of your computer versus out of an audio interface!

Connect Better Gear

As well as having better electronics designed for higher audio quality, interfaces allow you to connect higher quality audio gear, for example, the microphone input comes in on an XLR connection, giving you the option of connecting professional microphones.

In the same way, you can connect powered speakers to the speaker outputs, or power professional-grade headphones on the headphone output.

There are a few core features that pretty much any audio interface will have. These include:

To get audio in, you have what’s called a Microphone Preamplifier, or a Mic Preamp. As the name suggests, this amplifies your microphone signal to get it up to a good level.

The amount of amplification is controlled by the gain, which is normally a control on the interface itself. Different interface preamps will all sound very slightly different from each other and can offer different amounts of amplification and overall audio quality.

A bad quality preamp might not boost the signal very much, and can also introduce noise, normally in the form of a background hiss when you try and turn it up.

An audio interface gives you more control over your audio from a single device. So rather than having to mess around with connecting things round the back of your computer, or adjust settings deep in your preference menus, you have control over your input levels, your speaker, or headphone volume, and you can directly connect and disconnect things from on device on your desktop.

Being designed for audio, interfaces will usually have some pretty useful features on them to make your life easier when recording. For example, our EVO audio interfaces have the SmartGain on them which will automatically set the optimum input level for your recordings! An absolute lifesaver when needing to work quality, or trying to record things on your own!

Interfaces will often have more than one input, meaning you can record multiple things at once, whether recording guitar and vocals at the same time or running a podcast with multiple speakers.

The Line Inputs are for instruments or devices that have what are called “Line Level Outputs”. These are things like keyboards, synthesizers, or DJ decks.

Unlike Microphones which require lots of gain, or amplification, line level equipment will generally be coming in at a pretty decent level, which is why it comes in on a separate connector, usually, a quarter-inch jack, often built into the same connector as the Mic Preamp XLR.

For those that play guitars or basses, an instrument input allows you to record it properly. These are often also referred to as Hi-Z or D.I inputs. On the iD and EVO ranges, you can see it on the front, using a quarter-inch jack connection.

When you bring audio into the audio interface, it is analog, meaning that it is just variations in Voltage in a cable. Our computers work using binary, strings of 0s and 1s, so the audio interface must convert this variable voltage into digital information.

The same happens to get audio out of the computer, a conversion must take place from digital information, into a fluctuating voltage which in turn is changed into fluctuating air which you hear as sound.

Converters are chips inside the interface which handle this, and similarly to the mic preamps, different interfaces will use different converters, and therefore you will find different audio quality depending on the device you use.

Interfaces will usually have connections to plug in a set of speakers. These are different from your average computer speakers and are often referred to as Studio Monitors.

The headphone outputs are designed to run your headphones correctly. So if you are using slightly higher-end headphones compared to the earbuds you get with a phone, for example, the headphone output will be powering them to the best of their ability.