Why do I need an audio interface?
If you are in the market for a new audio interface, you may well be overwhelmed by the amount of choice available. While this means that there is a good chance the perfect interface for you is out there somewhere, it also means that there are an awful lot of products to look at, with different interfaces offering many different options and specifications, which can often make finding the right interface a bit of a challenge. In this guide, we’ll talk about the various options offered by modern interfaces and how you can make sure you spend your hard-earned on the right one.
The first question you may be asking is: ‘why do I need an audio interface? Why can’t I just use the built in soundcard in my computer?’ While it is possible to make some quite respectable-sounding recordings using your computer’s built in sound, an interface is one of the first upgrades that people often make for a number of reasons. One of these is simply to connect up more gear, such as having a dedicated guitar/instrument input or to add MIDI connections. Another reason is that of improved audio quality: the built-in sound is designed to offer basic functionality, while adding as little cost as possible.
Audio interfaces are designed with one thing in mind: getting quality audio into and out of your computer. They have more sophisticated analogue to digital conversion (turning sound into all those 1s and 0s for your computer to understand) and perform this using dedicated hardware, away from all those electronically noisy computer parts. Additionally, audio interfaces are generally provided with dedicated driver software, which can provide lower latency (the amount of time between playing a note on your controller and hearing it from your soft-synth) than onboard sound, making it easier to record parts in live.
Who are you?
Type of computer: One of the first decisions may well be determined by what type of computer you have: if you have a laptop, then internal soundcards aren’t an option, so you will be looking at external boxes. If you are using a Windows PC, then interfaces from certain companies -such as Apogee- are out, as they are Mac only. If you are using a laptop, or you don’t want to take your desktop apart to add a card, then an external interface is the way to go. These connect using USB or Firewire interfaces, but it is likely that more interfaces will appear that take advantage of the new Thunderbolt interface. The connectivity offered by your computer is likely to help you make up your mind here. If Firewire is an option on your computer, then sometimes a bit more research can be useful, as some interfaces can be temperamental about which Firewire controller the computer uses, so checking with the manufacturer can often be helpful.
Portability: If you are a laptop musician and you like to work on the move, or you need a mobile setup for carrying around to gigs, then how portable the interface is might be important to you. In particular, if you want to do a bit of producing in the coffee shop, then an interface that can be powered by the computer without you having to carry another power supply around with you might be an important consideration. Alternatively, you may decide to keep your soundcard wired in to your studio at home and just use your computer’s inbuilt sound for producing when you’re out and about.
Band, singer/songwriter, electronic…? The next factor you’ll want to start thinking about is what you are actually going to use your interface for. Are you a singer/songwriter, drummer, guitarist or bassist, keys or synth player, turntablist or dj? Are you in a band or do you produce solo? Do you want to use external ‘outboard’ gear in your setup? These are the questions that will determine what features and connections you’ll need on your interface.
Inputs and outputs
Once you know what sort of general interface you want, deciding what you need to send into your computer, and what you need to send back out is possibly the most important stage in choosing the right interface for you. For example, if you want to record your four-piece rock band to individual tracks for mixing later, your needs are going to be very different to a techno producer who works ‘in-the-box- using soft-synths.
Microphone inputs: As the name suggests, these are the inputs into which you’ll plug your microphones and are normally three-pin ‘XLR’ type inputs. If you are a singer/songwriter who wants to record vocals and acoustic guitar, you might decide that two of these are sufficient, if you want to record a choir or orchestra, you might want eight (or more!). These inputs may also offer ‘phantom power’ for using with condenser microphones. Phantom power may sometimes only be switched on or off for all microphone inputs at once, so check to make sure that this is compatible with the microphones you plan to use. Some interfaces also offer low-cut (high-pass) filters on the microphone inputs, which can be useful for getting rid of low frequency rumble when recording.
‘Instrument’ inputs: Guitars and basses like to see a particular kind of input (high impedance) to ensure the best quality sound from their pickups. Many interfaces offer ‘High-Z’ (high impedance) inputs specifically for recording guitars. These are on ¼” jack sockets, so you can just plug your guitar cable straight in. Sometimes, these inputs are shared with the microphone inputs using ‘combi’ sockets. So, if you want to record two singers and two direct guitars, and the interface says that it has two microphone and two instrument inputs, you may want to check that these aren’t shared.
Line inputs and outputs: Line inputs and outputs (I/O) are the workhorses of the recording world and can be used for a number of purposes. They can be used for plugging in your keyboards, outputs from guitar-modelling units, microphones that are amplified using separate preamps or channel strips, for connecting outboard gear such as compressors, equalisers or effects, and for connecting your interface to your monitor speakers.
Line inputs and outputs can be ‘unbalanced’ or ‘balanced’. Unbalanced I/O is usually on ¼” tip-sleeve jack sockets or RCA phono-style connections; balanced I/O uses XLR or ¼” tip-ring-sleeve jack sockets. Balanced connections offer a few advantages and can often reduce noise and hum in the project studio, particularly when you start to connect several pieces of equipment together.
Headphones: Nearly all interfaces will offer a headphone socket. In most cases, this is perfectly suitable to power the vast majority of headphones to more volume than you need. Depending on your application, you may want to look for an interface that offers two headphone sockets, either for two performers or a performer and an engineer. Some interfaces let you create independent headphone mixes to send to the two different sockets, and some may include effects, such as reverb, which can be added to the headphone mix, which can be helpful to assist singers pitching their vocals. Some interfaces may also offer direct hardware, or zero-latency, monitoring. In this case, the performer hears what they are playing directly from the interface, without the signal going into the computer and back out again, which can sometimes add a problematic delay to the signal.
Digital connectivity: Many interfaces offer additional connectivity in the form of digital I/O, most often using optical and RCA connectors. These are inputs and/or outputs that still require an analogue conversion stage, so you can’t simply plug the booth outputs of your dj mixer to a digital input on your interface, even though an RCA phono cable will fit. The most common digital I/O formats used are S/PDIF (Sony Phillips Digital InterFace), which can send two channels of audio down a single cable and can use both RCA and optical connections, and Alesis’ ADAT standard, which carries eight channels of audio (at lower sample rates) using optical connections. Some interfaces can use the optical connection to send four or two channels of audio at higher sample rates.
An interface with digital I/O can offer affordability for the initial purchase -as there is no need to include the additional conversion circuitry, but allow future expandability to suit the needs of the user. For example, if you require more microphone inputs, there are a number of eight-input microphone preamps that can output on ADAT, or you may have an outboard reverb unit with S/PDIF I/O that you can quickly patch into your studio and avoid additional analogue/digital conversion steps. Of course, if you simply want to add additional analogue line ins and outs, there are a number of standalone converters available.
Digital connectivity, while often not immediately useable without additional compatible hardware, is still included in the specifications list of an interface. If you are in the market for an interface with plenty of I/O and see something described as ‘20in/20out’, it’s worthwhile checking to see what they are including in that number. Searching for hi-resolution images of the back and front (and the sides in some cases) of the interface can often be helpful in working out what connectivity is provided.
As the majority of MIDI controllers connect via USB these days, you may not have any need for traditional MIDI sockets. However, if you have external hardware, such as drum machines, samplers or synths, you may be interested in hooking these up to your computer via MIDI to allow you to program or trigger them from your DAW, or synchronise them via MIDI clock. If you have found an interface with the perfect audio I/O for your needs, but it lacks the MIDI connectivity you were looking for, a separate USB MIDI interface may well be a good addition.
Your audio interface is one of the few pieces of gear that you are going to use every time you power up the studio; because of this, it’s going to get old very quickly if it’s frustrating to use. In many cases, this isn’t a problem, once it’s installed, you can quite often forget about it. However, if you’re regularly setting recording levels and configuring phantom power and zero-latency headphone mixes, you’re going to want an interface with which you get along. Does the interface offer individual knobs, switches or buttons for specific functions, or do you have to go through multiple presses and twirls of a single encoder? Does the interface have an application that allows you to configure it from your computer? Once you’ve found a few interfaces that look like they are a good fit in terms of their features and specifications, it’s worth spending some time searching for some user feedback about ease of use and ergonomics. Your studio time is supposed to be creative, you don’t want to waste time getting frustrated with your gear.
Audio Interface Buying Guide: Summary
In this buyers’ guide, we have tried to quickly cover a lot of the areas you may wish to think about when buying an audio interface. If you have answers to some of the questions posed above, and you have a budget in mind, chances are there is an interface out there to suit your needs and, if not, there is usually a way to make one, such as by adding an outboard microphone preamp or a separate MIDI interface. Your audio interface might not seem like the most inspiring piece of kit in your studio, but if you’ve picked the right one, you should almost forget it’s there; it should just be getting on with the job and letting you get on with the business of making music.
Red Dog Music is the UK’s friendliest musical instrument and pro-audio dealer. Between our 5000 square foot Edinburgh shop filled with an incredible range of products, and a London showroom in Clapham specialising in high-end instruments, dj and pro-audio, Red Dog Music has you covered from north to south and from performance to playback.