Audio Interfaces – What are they and why do I need one?
What exactly is an Audio Interface?
When it comes to building a studio – regardless of whether you’re squirrelled away in the corner of a garage or designing your own Abbey Road – audio interfaces represent one of the most pivotal elements of any set-up. The more seasoned computer musician will remember the golden age of the ‘sound card’ – a clever module that could be bolted in to your physical computer rig in order to significantly boost the audio input and output capability compared with the lacking consumer sound card installed by the manufacturer. Audio interfaces are the next generation of sound card technology, offering a number of key benefits over their predecessors.
By replacing an internal computer component with an external box – which connects to and is powered not by the computer’s innards, but by one of its ports – these audio interfaces are easier to install and more convenient to use than ever before, offering far less noise, interference or latency as a result. Unlike a sound card, an interface can host a myriad of its own accessible knobs, dials and connectors for direct, simple control.
What does it do – and why do I need one?
Think of an audio interface as a bridge between the musician and the computer. On one end, you have a singer with a microphone or a guitarist with an electric guitar or bass. On the other, you have a computer running a DAW program (such as Cubase, Logic, Ableton Live) with a track loaded up and ready to record. The issue is that standard computers don’t have XLR or 6.3mm Jack connectors for connecting your microphones and instruments, or the specialised circuitry to take the analogue signal of a mic/instrument and convert it into a digital data file that can be added, edited and mixed into a DAW project.
This is the main purpose of an audio interface – connecting directly to your computer via one of its USB/Firewire/Thunderbolt ports, an interface features input sockets for your microphones and instruments, with many even offering MIDI ports for controllers and output connectors for directly attaching the interface to a set of studio monitor speakers. This little hub takes the analogue signal of your microphone or guitar and converts it in real-time to a digital format file, which is automatically imported into your DAW of choice.
So, as you can see, an interface really is an essential component of any studio.
Interfacing with your Interface – A Glossary of Key Terms
While most interfaces may be simple to hook up and get going with, like most computer-related equipment, there is quite an amount of techno-terminology involved to understanding them. Here are some of the most commonly encountered terms that you’ll want to know in order to get your head around what exactly your new interface has to offer:
Bit Depth
A measurement in ‘bits’ that identifies the resolution of a sound sample. Essentially, the higher the number, the greater the resolution – and the better the overall sound quality.
Sample Rate
The number of samples of an analogue sound that are processed per second to produce the digital file on your computer. The sample rate determines the maximum audio frequencies that can be reproduced in a recording. The higher the rate, the wider the range of frequencies that can be clearly captured in the digital recording.
Phantom Power
Usually in the form of a switch or button on your interface, Phantom Power sends out +48V of power to one or more inputs. This boost in power is necessary to provide adequate amplification power for condenser microphones. Without this switched on, your microphones will either fail to record or will record with inadequate volume and clarity. When using XLR-powered condenser microphones, always enable phantom power. **Note: NEVER use phantom power with ribbon microphones, as this can cause irreparable damage to the mic!**
Input/Output
The connection ports on your interface. Microphones, instruments and controllers are your INPUTS and audio playback devices, such as monitor speakers, are your OUTPUTS.
What types of audio interface are available?
In terms of the interface itself, there are really two main options – portable desktop or rack-mounted. Which you buy depends on your own particular needs.
Generally speaking:
Portable desktop interfaces are light and compact, taking up only a small amount of desk space. They are ideal for home studios and for mobile producers who need absolute portability and a rig that can travel around with them without making a fuss. They usually offer up to 4 inputs at a time and are primarily powered by USB – the most universal standard of computer connection available on the market today.
Here at Inta-Audio, we sell a range of excellent portable interfaces – some of our most popular recommendations are:
Rack-mounted interfaces are designed for larger studios with existing studio racking furniture. Often much larger than portable interfaces, they do not offer the same level of portability as their little brothers, but make up for this with raw power. Most rack-mountable interfaces can handle a significant number of inputs, with many offering 8 ports for simultaneous use of your microphones and instruments. The range of output connections and control knobs and dials is also often significantly more comprehensive than those found on portable interfaces. The caveat of this, of course, is the size and the price – both of which can be quite substantial!
Some notable rack-mounted interfaces to take a look at include:
- MOTU 828MK3 (Hybrid FireWire & USB Audio Interface)
- RME Fireface UFX Audio Interface
- Behringer ADA8200 (Audiophile 8-in/8-out Audio Interface)
- PreSonus Quantum (26×32 Thunderbolt 2 Audio Interface)
Making a Connection – Connectivity Options
As previously mentioned, most interfaces – especially the portable models – are powered by USB. However, this certainly isn’t the only option available. Different interfaces offer different types of computer connection and some are notably faster than others. Here is a list of the most popular and their maximum rated transfer speeds in Megabits-per-second (Mbps), with faster connections shown instead in Gigabits-per-second (Gbps):
USB 1.1 – 12Mbps
USB 2.0 – 480Mbps
USB 3.0 – 5 Gbps
USB 3.1 – 10 Gbps
FireWire 400 – 400 Mbps
FireWire 800 – 800 Mbps
Thunderbolt – 10 Gbps
Thunderbolt 2.0 – 20Gbps
USB is the most widely-available type of connection with almost every PC device hosting at least USB 1.1 ports – most computers and laptops from the last decade will have USB 2.0. Be aware that only more recent models of computer (from mid-2013) will have USB 3 ports.
FireWire is an alternative to USB that was especially popular back when USB1.1 and 2.0 offered lower speeds than the current standard. With the introduction of USB 3.0, however, users of most post-2013 manufactured computers would be arguably better off sticking with a USB 3.0 powered interface.
Thunderbolt is a connection type marketed by Apple and is specific to Mac computers. If you have a Mac product with Thunderbolt ports, you can get blistering transfer speeds compared to any USB connection – however, Thunderbolt interfaces are quite rare, only usable on Macs and often command a significantly higher price than their USB counterparts.