WHAT IS AN AUDIO INTERFACE

WHAT IS AN

AUDIO INTERFACE

By G-Mohris

Author

What is an Audio Interface, or Soundcard? A question i always get asked by customers and students who are stepping into the realm of digital music production, recording, performance, or DJ.

An Audio interface is a bridge between the digital domain and the analog one. The world of computers and the world of electricity. It is a translator of languages, a converter of signals.

The Audio Interface is one essential unit that should be present in your studio setup for without it audio processing and conversion is at stake.

Let’s discuss the importance of the Audio Interface, its uses, and applications. You can check out our selection of interfaces here →

THE THREE DOMAINS

There are 3 main domains that you should be aware of whenever you are dealing with audio production, recording, performance or DJ

The Acoustic Domain

This is simply the air domain. Imagine yourself sitting in a room with someone playing acoustic guitar, the moment they start plucking the guitar strings, there will be a vibration of air molecules, an energy field that pushes and pulls in cycles. That’s how you hear the guitar. Because of the air medium, sound traveled to you.

The Analog Domain

This is the domain of electricity. Information is encoded in terms of signal amplitude, usually the intensity of the signal at any given time. The signal that travels from let’s say a DJ Mixer to a Speaker through the analog cable such as XLR or RCA is an electrical signal, meaning an analog signal, this is the business of voltage.

The Digital Domain

Mainly this is the domain of computers, the digital devices such as mobile phones, tablets, computers and any digital device. In the digital world we are in the business of binary language, zeros and ones.

RECORD & PLAYBACK

Record

The microphone’s job is to convert acoustical energy (sound waves in the acoustic domain) into electrical energy (the audio signal in the analog domain). It is the medium through which acoustic signal gets translated into an electrical signal which is still a signal that is not understood by computers.

This electrical signal has to be translated into another form of signal, a digital signal, which the computer can understand and process.

Whether you are using a Condenser Microphone or a Dynamic Microphone to record vocal or instrument into your computer’s digital audio workstation, you need a converter to translate the signal from analog to digital. and this is the job of an Audio Interface.

The Audio Interface receives the analog signal (traveling through an analog cable) and converts it into a digital signal, bunch of binary information that will be sent to the computer’s central processing unit via a digital cable such as USB. This is called an A/D conversion (Analog to Digital)

You might be wondering then how do you often record your voice-note on your mobile? Well, it is the exact same process. The mobile has a built in audio interface and a microphone. Once you start recording, the microphone converts the acoustic energy into an electrical signal which reaches the audio interface and gets converted into a digital signal. Got that?

Playback

Everything you hear out of your digital device, be it a computer or a mobile phone etc.. was at one point a digital signal. The Audio Interface is now acting as a D/A converter, meaning, converting the digital signal to analog electrical signal which the speaker can understand and accept.

So to record inside your computer or audition any sound, you need an audio interface that acts as an A/D and D/A converter.

OTHER BENEFITS

Latency

Latency is one major issue in both recording, audio production and even playback. It is annoying and sometimes unbearable to have the signal received or sent out later than the playback time.

Imagine you are recording vocal, and you are hearing the reference music on headphones.. singing along is impossible with latency issues. You will not be in sync with the music, even sometimes you would hear your voice twice.

Latency is also an annoying issue when it comes to music production as some producers find it very uncomfortable to play a note on the keyboard and hear the result late, not instant.

The Audio Interface solves this issue as it can sample the signal at a fast rate, and/or reduces the buffer. Both processes will contribute in having a fast response and unnoticeable latency.

Sampling can happen at rates ranging from 44.1 Khz and 192 Khz. The higher the rate, the faster the process, and therefore the lower the latency. However, this depends on your computer’s CPU, if it is not powerful enough to handle this rate, then it will introduces audio drop outs and pauses/glitches in the audio flow.

Phantom Power & PreAmp

Condenser Microphones have a built in battery that requires +48v power. And this is provided by the Audio Interface with what’s called Phantom Power. The condenser needs power either to drive active circuitry, or, more usually, to polarize its plates

When you record a sound with a microphone, the electrical signal that’s generated is actually very weak. So before the signal is passed to other studio devices for further processing, it needs to be boosted. This is the job of the preamp..

MIDI

Most high-end audio interfaces will have an onboard MIDI connection meaning they can also act as a MIDI to USB converters, taking the MIDI signal in from a keyboard or control board and translating it into a USB MIDI signal which the computer’s digital audio workstation can understand. This can also send out MIDI information from the digital audio workstation to the external world, to control and trigger analog synthesizers, drum machines, and even light systems.

Multiple Ins & Outs

One of the great features an Audio Interface can have is providing multiple input and output ports.

If you want to plug in more than one microphone or more than one instrument or line inputs, then you need multiple inputs. This way, multi-track recording is possible

Multiple outputs are also important when you want to output the master audio to different speaker systems, or split your master output and headphone monitor output, or even output different audio channels when DJ’ing using a table dj mixer such as Pioneer DJM 900 Nexus 2

HOW TO CHOOSE?

Choosing an Audio Interface is not a hard task only when you understand what they do and what they can offer to you.

Based on what you need them to offer, you can choose the best one that fits within the scope of your use. Why buy something that offers more that what you need? and why buy something that doesn’t serve you best? I have included some links to my recommendations (based on the current time July 2022)

By the way, i have written a blog post that includes our store recommendations. Check The Best Affordable Audio Interfaces Here

If you are a musician or vocalist and you want to record your vocal or instrument into your digital audio workstation, then you surely need an audio interface that offers at least one input such as the Native Instruments Komplete Audio 1 or the Arturia Minifuse 2. Most audio interfaces offer a PreAmp that amplifies the low level microphone signal, and a phantom power that is essential for any condenser microphone to function. It is essential to check the sampling rate and the bit depth these audio interfaces offer. Best is to go for 192Khz and 24bit (32bit for more detailed recording)

Should you be in need of multiple inputs, meaning you want to record multiple instruments or vocalists at the same time (however on separate channels) then you need an audio interface that offers more than one input. Some interfaces offer more than one PreAmp and more than one phantom power, this way you can record more than one microphone. A good example would be the M-Audio Air 192|14 or the Focusrite Scarlett 18i20 G3. This is also useful when you are recording a band or multiple sessionists, or when you are performing live and you want to use your DAW as an effect hub or a looper

Let’s say you are a DJ and you want to output the audio channels of your DJ software such as Traktor Pro or even Ableton Live to a DJ Mixer such as the Pioneer DJM900 Nexus 2 or you want to split the main master output and the headphone output, then you need to have an audio interface that offers multiple outputs. Your aim here is not to record any instrument or vocal, rather to have your software channels sent out of your DJ software to a table mixer where all the mixing happens. A great example would be the Native Instrument Traktor Audio 2 or the Native Instrument Komplete Audio 6 this one offers MIDI connectivity as well, in case you are a live performer and would like to send and receive MIDI information to route your analog synthesizers or drum machines.

Live podcasting and streaming is a trend nowadays. Some brands such as iK Multimedia offer special audio interfaces for mobile use. Simply plug your guitar or microphone or even a DJ set and start streaming professional audio quality. A great example can be the iRig 2 or the iRig Stream

Some music producers prefer to send out the channels from their digital audio workstation to an analog summing mixer, and some want to mix in surround. this way more outputs are required.

There are audio interfaces that do not have any inputs therefore do not offer PreAmp nor phantom power, these can be used to replace the built-in audio interface that comes with the computer or laptop or mobile devices, and that is usually not fast enough nor optimized for professional audio processing. A great example can be the M-Audio Air Hub that offers a powered USB Hub and a sampling rate up to 96Khz.

Many audio interfaces come with onboard digital signal processing and DSP-based mixers, providing built-in effects, dynamics, equalization, and monitor mixing. This allows you to put reverb or delay on vocals for monitoring, or sometimes to record with EQ and compression, all without adding latency to your system. A good example would be an audio interface from Universal Audio

Don’t Be Fooled

Buying the fastest audio interface that can have a sample rate of 192Khz does not mean that you can always use this rate and therefore have a super low latency. Don’t be fooled by these numbers.

It is true that the audio interface’s job is to translate the signal and process the audio on a very fast rate, however if the computer’s CPU is not fast enough to process this data, then the audio will fall out of flow and will start to drop out. So, the computer’s brain and resources are the ones that you should be looking at first.

Another misconception is that people think that a higher sample rate will result in a better audio quality. This is not true. The quality of audio is the same when processed at 48Khz or at 192Khz as both rates are going to output the full frequency spectrum.

TO SUM UP

The Audio Interface is a converter of signals, a translator of languages, and a medium that connects the world of the digital and the world of the analog

There are 3 domains: The Acoustic, The Analog, and The Digital.
The Audio Interface is one of the most essential units in any studio set-ups. It converts the signal from analog to digital and vice versa. It also processes the sound, and it has a Pre-Amp. It is a requisite to solve latency and audio drop out issues.
Some Audio Interfaces have a MIDI Converter.
One of the benefits of Audio Interfaces is that they provide multiple inputs and outputs.
Choosing the best audio interface depends on what you need them to do for you.
Audio interfaces with high sampling rate do not necessarily provide you with a better quality audio.
Buying a 192Khz audio interface does not mean you can always use it at this rate.