An Audio Interface Primer

The audio interface is an integral part of the recording chain. But it's also kind of nebulous, and hard to figure out sometimes. Just what is it, how does it work, and what do we need to know about it?

The recording interface is the last step in the chain before your audio goes to the computer. The sound goes into the mic, is converted to electrical signals, passed along through cables and a mic preamp, and into the audio interface. There (or before, in some cases), it is converted from analog to digital, and passed on to the computer via FireWire, USB, or another third party connection.

There are many kinds of audio recording interfaces available, from a small one or two channel interface including mic preamps to a huge system of three interfaces daisy chained together for 72 channels. The confusing thing is that often an audio interface does more than just interface, so we need to figure out exactly what it does do.

The main job of a computer recording interface, as we said earlier, is to convert an analog signal into digital, and shuttle it to the computer. So we'll say that a audio recording interface is something that takes analog or digital audio, and has a FireWire, USB, or other computer connection.

Often these interfaces will come with extra features, like mic preamps or bundled software. This is where it can get confusing, but it doesn't have to be. Think of it this way - with the preamps included, you don't have to buy a separate piece of equipment. That's a good thing.

Here is a quick survey of several interfaces here to give you a taste of what is available.

The Lexicon Lambda is a great entry level interface. This is a no sweat, easy working interface bus-powered USB interface with two phantom powered preamps, two TRS 1/4" line inputs, and a headphone output. Definitely a lot of power for not that much dough. It's worth a look.

For only a slight step up from the Lambda, one can get a Lexicon Omega package. The spiff with this is that you get a complete kit, kind of like a "studio in a box." There are two phantom powered XLR inputs plus a bunch of others, allowing for a total of 4 simultaneous channels.

The next one is a MOTU 4-Pre. This is a really nice piece of gear, with four mic preamps. I think it hits the spot between a low of 2 and a high of 8. I use MOTU equipment, and I would really like to have this for a portable setup.

Motu 4-Pre Audio Interface

Looking at the FireWire side of things, we have the Focusrite Saffire LE, a step up from what we were looking at. It has 6 inputs and 8 outputs, a bit more than the Omega. The Saffire is also sold with a package, with a number of plugins: Compression, Reverb, EQ, and Amp modeling.

Presonus Firestudio Project

PreSonus makes some nice equipment, including audio interfaces and mic preamps. But with the PreSonus FireStudio Project, these two high quality pieces come together. The FireStudio offers pro quality preamps and digital to analog coverters - eight of them. It takes a while to run out of eight channels. Included with the FireStudio is the PreSonus ProPak Software Suite, which sports a DAW (digital audio workstation), over 25 plugins, and more than 2 GB of audio samples. If I were starting again, I would seriously consider this piece, simply for the EIGHT mic inputs combined in one unit.

MOTU 828 mk3

Finally, what I consider one of the best audio interfaces, is the MOTU 828mk3. I use it myself, so I might be biased, but it still is a great piece of gear. It includes two XLR inputs with preamps, but accepts 8 analog inputs, and two different banks of digital input (ADAT, TOSLink, and S/PDIF), for a total of 28 inputs and 30 outputs. Clearly a big machine. It can also serve as a digital mixer, and includes MOTU's AudioDesk software for Mac. If you want opportunity for future expandability, this is the way to go. I love my 828. I don't think you can go wrong with it. 🙂

Don't let me limit your choices to these - go check them out yourself. What I showed you here is only a sampling of what's available. See them in their categories here:

About the Author Lee Weaver

Lee started his career in recording with an auspicious goal - record tracks of his own voice singing in harmony. As a hobby project, it didn't have the funding to go to a studio and pay for someone to do it for him. Like many of you, he pulled himself up by the bootstraps to learn the art of recording.

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