Guide To Choosing The Best Audio Interface
The audio interface can be a confusing world for newcomers to the world of recording. What exactly do these magical boxes do? We asked this question to Pat Rodgers, who jotted down the basics of what to look for in an interface, what they do, and advice on how to choose the best audio interface for your studio.
Audio interfaces receive an analog signal from a microphone/instrument, convert it to a digital one, and send it to your computer for your DAW to manipulate. They then convert the signal back to analog so that you can send it to monitors and outside gear.
In the home studio the audio interface is one of the two crucial things you need (the other being your DAW).
How well the signals are converted is the marker of an audio interface’s quality. You’ll see things like ’24 bit’, ’16 bit’ and other large numbers. These have to do with the dynamic range of the audio. The higher the numbers, the more information your DAW can work with. In the home studio you can’t go wrong with gear which is ’24 bit’ and operates at ‘48,000Hz’. This covers all of the frequencies that humans can hear. Many cheap interfaces operate with larger numbers but the conversion simply isn’t good enough to be useful.
There are three common ways of hooking up an interface to your computer. Why so many, and what makes them different?
The key word is ‘latency’.
Put simply, latency affects the delay in which digital information comes into your computer. The lower the latency, the less delay there is between your voice and your DAW. It would be a problem if your vocals were slightly out of time with a beat or vice versa. Unfortunately lower latency comes at a price, but most DAWs have decent ways of compensating for these issues so it’s rarely an end-of-the-world scenario.
The reason that there are multiple connection types is related to how much latency they introduce.
- USB connection is so commonplace that you can use these interfaces with any PC or laptop. The range of USB audio interfaces available on the market gives you the ability to choose from basic entry-level equipment to very versatile and high-quality gear. No matter your budget you can be sure you’ll find something to suit your needs. However, it’s also the medium with the highest latency. A crucial point is that they don’t require external power.
- Firewire is consistent and slightly faster than USB, the downside of which is that it increases the cost. Standard PC and laptop setups don’t usually have a Firewire port, in which case you will need to install one. If you own a Mac you should check if it supports Firewire. There are slightly fewer of these out there compared to USB. It’s best to choose this option if there is something about a particular Firewire audio interface that you think you will need.
- Thunderbolt audio interfaces can easily manage over two dozen separate streams of audio with almost zero latency. They also boast a range of hardware and software features. Naturally these interfaces are very expensive. In our situation, I wouldn’t think about going down this road just yet.
We’ve categorised them, but we’re still left staring at hundreds of options.
The first way of narrowing down your options is by thinking about what you want to feed into your DAW.
As vocals are our primary interest we’re looking for microphone inputs. Realistically you’re not going to need to use more than two inputs at a time. The stock-standard audio interface often has just two.
The difference between ‘good’ from ‘bad’ mic inputs lies in their preamps. You want one which makes the signal louder without hum or hiss even at very high levels. It is true again that you get what you pay for, however for home recording it’s unlikely you’ll need high levels of gain.
Additionally most audio interfaces have instrument and MIDI inputs, so you can connect keyboards, drum machines, turntables and other equipment.
As you’re most likely to be using a condenser microphone you need to look for one more thing. If there’s a switch on the interface which says something like ‘+48v’ or ‘phantom power’, then you can use a condenser as they require more voltage. Usually the switch is located near the mic inputs.
Make sure that switch is engaged after plugging in your mic and use it only for condensers!
Some preamps will ‘colour’ the incoming signal. If you want your vocals to come in as you hear them then avoid interfaces with these inputs. You may like to have a bit of low end ‘warmth’ or high end ‘air’ depending on your style.
How do you hear what’s going in? What comes out?
There are a few ways of hearing what’s happening in your DAW. All audio interfaces have basic headphone outputs for monitoring.
If you’re using high-quality monitoring headphones, investigate the interface’s headphone amp. Without proper amplification your cans won’t give you enough power for you to hear your recording/mix.
Some models have a very useful “dry/wet mix” knob which allows you to hear your voice as it sounds before any processing at all in your DAW, making monitoring yourself when recording extremely accurate.
For mixing purposes an audio interface contains ‘line level’ outputs. Through these you can connect to your studio monitors and connect to headphone amplifiers with multiple outputs.
This is all fine when you are setting up a home studio by yourself.
But what if you’re in a booth and you want to talk to the engineer?
We need a ‘talkback’ system. This enables the engineer to communicate with you through your headphones when they’re outside the room.
For this scenario you’ll need to have either an interface with multiple mic inputs and headphone outputs or an interface connected to a separate headphone amp.
The basic idea is that the engineer can patch a microphone into one of the headphone outs (yours) and talk to you through your headphones, while you can talk to them via your microphone. There are interfaces which have a complete built-in talkback function, but it comes with a cost.
Investigate hardware which allows talkback only after considering realistically whether you’re going to be in recording booths regularly.
How much should I spend?
It all depends on which features you feel you really need. If you are kitting out a fairly complex studio situation with a booth and angling for clients, you'll definitely want to spend more. The entry level for an audio interface is quite on the cheap side however, and the difference in quality to the untrained ear isn't vast. I always find that with audio equipment, there is a huge jump in quality from your sub-$100 range to a similar product valued at $500. The jump in quality from $500 to $1000 is quite big again, but not as vast as before. When you start getting into $2000+, you are dealing with tiny margins, but if you know what you are looking for it ends up being worthwhile.
If you're just starting out, I recommend getting a solid budget USB interface, like one of the Focusrite Scarlett models. They have everything you need to connect to and from your computer, and have surprisingly high quality preamps for the price. If you are looking to upgrade, then always do a lot of reading before making a purchase. Sound On Sound is a great resource for finding out what is good in the world of audio! Even better, if you have a local retailer that will let you try things out in a demo room, then head down there and chat to them. Take your mic of choice and utilise their demo rooms - they'll be trying to get a sale out of you so will be more than accommodating!