what is an audio interface

What Is an Audio Interface?

Computers are not generally well suited to the ins and outs of music production. Although they are very capable of processing sound, mixing audio and generating any noise imaginable they tend to be a bit lacking when you want to plug in a guitar, microphone or even a proper pair of speakers. You might find some minijack connectors round the back of your desktop. On your laptop, you might have some terrible inbuilt speakers or even an integrated microphone, but these are not the tools of the serious musician.

So how do we bridge the gap between the computer and the studio, between the laptop and your guitar? What is an audio interface and what advantages can we gain using one?

Connections

The first thing an audio interface brings to your setup is the proper connections needed for music making. A typical audio interface will have two or more microphone inputs with XLR connectors and phantom power for condenser microphones. They usually have high impedance (Hi-Z) inputs for guitars and similar electric instruments on proper 1/4″ jacks. Then there can be a number of line level inputs for recording synthesizers, mixer outputs and the sound of other hardware you have in your studio. Your inbuilt microphone has just been replaced with a multi-channel recording interface with professional connectors. Plug yourself in, plug your band in — in fact with the right hardware you could plug in an entire live orchestra.

An audio interface can also give you outputs. You can route these outputs through external hardware and sound processors. If you prefer mixing outside the box, then it can take tracks from the computer individually through an external mixer. You’ll also find a headphone output, usually with its own level control. Often there’ll be two, one for you and one for your singer.

The number of inputs and outputs can range from a single input (great for portability) through to over 100 channels of digital connection but somewhere from 2 to 16 in/out is commonplace.

Physicality

If you are plugging a lot of cables in and out of this interface, then it needs to be able to handle the weight so that it doesn’t get dragged off the desk. Many larger interfaces are in 19″ rack format so that they can be screwed into a rack system and be totally secure. Smaller interfaces tend to have a weight to them, and rubberized feet, to prevent them slipping. Constantly plugging headphones into those little minijack sockets on your computer tend to break and become ruined quite quickly — that’s not going to happen with an audio interface. You’ll have a single cable going to your laptop but everything else will be plugged into the audio interface.

If you are writing your own tunes and singing your own songs then you don’t need much, but you need it to be good. The Scarlett Solo from Focusrite offers a single microphone input and an instrument input that’s perfect for you and your guitar.

Quality

You can spend more on your audio interface than you do your computer. (Well, not usually, but you should expect to pay from $100 upwards.) The price will vary depending on the features, amount of i/o and the quality of the internal components. But that’s the point. The sound components of your computer cost a few dollars at best and so the quality of the recorded audio will reflect that. In an audio interface, the converters that do the recording (they process the sound into a digital form) account for most of the hardware cost. So, the sound you’re recording is going to sound a whole lot better. The recording will be more transparent, with a bigger dynamic range and a professional tone. Don’t be fooled by the specs that get published for onboard sound. The ability to be able to play back 192kHz audio is for HD movies and does not reflect the computer’s ability to record cleanly.

Audio interfaces are commonly 24bit and up to 96kHz but as any Sound Engineer will tell you, 24bit and 48kHz is plenty for most environments.

And it’s the same on playback. If you want to properly hear your music, then high-quality outputs are essential. You can get by with earbuds and a minijack output but it’s not going to let you easily analyze your sound, mix your music, work on dynamics and the depth of your frequency spectrum. With an audio interface, you’ll get professional quality monitoring through both the headphone outputs and the main outs to your speakers, with the added bonus of a proper volume knob.

Latency

The other most important factor an audio interface brings is the ability to record, playback and monitor in as-near-as-dammit real-time. It always takes a finite amount of time for your computer’s CPU to process audio into and out of your computer. This results in a certain amount of delay. If you are using software instruments then that delay is the time between hitting a key on your MIDI keyboard and hearing the sound of the instrument through your speakers. If you are live recording then it’s the delay between your actual voice and hearing it through your headphones. Using onboard computer sound the latency (delay) can be very noticeable to the point that it becomes useless. With an audio interface that delay is reduced to under 5-10ms. That’s about the same as standing 3 feet from your guitar amp while you’re playing. In other words, it becomes unnoticeable.

If you are monitoring through the computer when recording then the delay can creep up even on a proper interface, especially in a large project where the CPU is being taxed. To get around this, an audio interface often has a “Direct Monitoring” open where the audio is routed directly back out again, bypassing the computer and not experiencing any processing delay.

Other Features

You’ll often find other advantages to the audio interface. They often have physical knobs to control the sound which are far better than using a mouse or function keys. You may have a number of different speaker outputs for comparing mixes, you might have LED monitoring and peak lights: all the stuff that helps the Producer or Engineer deal with professional recording.

The RME UFX offers up to 94 channels of I/O over ADAT and MADI (another digital format) but it also has a bunch of inputs ready to go for when you need to just plug something in and get it recorded. The UFX connects via Thunderbolt or USB and even offers the ability to record multi-channel audio directly to a USB thumb drive, bypassing the computer altogether. At $2,799 it’s in a very different place to your regular audio interfaces, but professional tools always are.

USB, Thunderbolt or Firewire?

The last consideration is how it connects to your computer. There was a time when an internal card was the best option, known as a “soundcard.” But you are much more likely these days to make the connection externally via USB, Thunderbolt or Firewire. Firewire is a dead technology and you’ll be pushed to find new interfaces with that connection. Thunderbolt is still a slowly emerging technology, but it does offer very low latency and high data rates. USB is by far the most common and completely capable of offering many channels of audio at very high quality. It makes no difference to the quality of the audio or the capabilities of the interface, you should choose the format that best matches your computer.

Example 1: Singer-Songwriter

Audio Interface – Focusrite Scarlett Solo

If you are writing your own tunes and singing your own songs then you don’t need much, but you need it to be good. The Scarlett Solo from Focusrite offers a single microphone input and an instrument input that’s perfect for you and your guitar. It’s got a nice fat volume knob and a headphone output right on the front. The gain knobs light up to show you an indication that your recording levels are right. It’s metallic, high quality, very portable and can be powered by your laptop over USB. For just over $100, it comes with some recording software to get you started.

Example 2: Recording the Band

Audio Interface – Audient iD44

So, you’ve got a band rehearsing in your garage and you want to record the session onto your computer. For that, you’re going to need inputs, lots of inputs. You could stick a microphone in the middle of the room, but you know that’s going to sound terrible. Individual miking is the way to go. So, you’ll have at least one guitar, one bass, a keyboard player, singer or two and then, probably, the enormity of a drum kit. So that’s a minimum of 6 inputs and more realistically 12. The Audient ID44 has 4 console class mic preamps that you could use directly with your singers or guitar cabinets. Twin DI inputs give you perfect inputs for instruments. For a small band, it’s perfect but to incorporate a drum kit or more instruments then you’ll need to use the digital ADAT inputs on the back. ADAT inputs are 8 channels of audio and a great way to expand an audio interface. You’d need to buy an 8 channel ADAT box which would give you another 8 microphone or line level inputs. For an extra $200, a Behringer ADA8200 would do the job. You could add 2 and now you can record up to 20 channels directly into your computer.

Example 3: Professional Solutions

Audio Interface – Fireface UFX+

In a studio situation, you need to route audio from all sorts of places. You’ll be using a lot of outboard gear for your preamps and DI inputs. The RME UFX offers up to 94 channels of I/O over ADAT and MADI (another digital format) but it also has a bunch of inputs ready to go for when you need to just plug something in and get it recorded. The UFX connects via Thunderbolt or USB and even offers the ability to record multi-channel audio directly to a USB thumb drive, bypassing the computer altogether. At $2,799 it’s in a very different place to your regular audio interfaces, but professional tools always are.

Conclusion

An audio interface is an integral part of any computer-based studio. An audio interface allows you to amplify, fine-tune, and record live audio with your computer by providing power and plug connectors for various cables and essential connections. Whether working as a professional or just mucking about with beats and your guitar, an audio interface is going to make the experience of music production with a computer a far more enjoyable and flawless experience. Spend $100 and your music will thank you and everything will sound a whole lot better. But spend as much as you like to get the features you need.

Check out our article on the best audio interfaces for a round-up of what’s hot.

Daily Music Career Info! Follow Us.

Jobs. Career Articles. Quality Blog Posts. School Info, & More.