Audio Interface Buyer's Guide For Beginners

Interface Buyer’s Guide

Have you seen the number of interfaces that are currently on the market? Well we certainly have, and we want to help you navigate the ever-expanding choices that continue to propagate. Your budget is the key in your quest for audio perfection, but then after that, the choices and decisions you have to make are virtually unlimited. From the number of inputs, to the connection types, to the host computer… there is a ton of ground to cover. But don’t let this deter you as the solution exists, and in some cases there’s the ability to expand once you grow out of your current setup. Let’s get started, shall we?

Primitive Audio Interface

What is an interface and why do I need one?

An audio interface’s primary function is to transfer audio in and out of your computer. It does this through analog-to-digital (A/D) conversion, or the input to the computer; and digital-to-analog (D/A) conversion, or back out of the computer. This information is going to be transferred through any number of data connections, e.g., USB, Thunderbolt, Firewire, and more. While some of these are not as common today, many are still in use, and as data speeds and busses continue to grow and change, this list of connection will follow suit.

Now, if you’re wondering why you need one, here’s the primary reason; recording music saves lives! I kid, but of course it does, right? But in all seriousness, an audio interface, as I mentioned in the previous paragraph, is going to be your conduit for getting sound in and out of your computer. There are ways to record using IOS, Android, and other myriad portable devices, but the fidelity is usually going to suffer, and you will probably transfer to a computer at some point, in which case an interface will allow you to continue your journey. An interface, unlike a computer’s stock sound card or audio facilities is going to offer advantages that you wouldn’t otherwise have. Better conversion, more inputs and outputs, better monitoring options, and much, much more.

What is the best interface for my computer?

And another part of this equation is; what DAW (Digital Audio Workstation) are you using? And the answers, believe it or not, are pretty simple. You will find that just about any interface you’re interested in is supported by the leading operating systems and DAWs. An even better question to ask is, what kind and how many connections (inputs and outputs) will I need to successfully achieve the results I already hear in my head?

Inputs and outputs and MIDI, oh my!

Yes, I said MIDI! But let’s hold off on that just for a bit. Today’s interfaces are going to offer anywhere from a mere single input to multiple inputs, and these inputs can support various connections and levels. The most common connections are going to be; XLR, more commonly referred to as a mic connection; and 1/4” balanced and unbalanced plugs, commonly referred to as instrument and line level. Output connections can also come in different formats. Smaller more budget conscious interfaces might incorporate RCA jacks for the output stage, while more robust and professional interfaces offer balanced connections in either the XLR or 1/4” format.

The number of inputs and outputs required is going to vary from person to person and project to project. A singer-songwriter might only need to utilize two inputs; one for a vocal mic and one for an instrument, which may require a microphone or a direct instrument/line input. Now the other side of the coin is that of a full band, which most likely consists of a minimum of three members. In this scenario, the drums alone, assuming there is a drummer, are going to use a number of inputs, and there are still the other members to consider! Multiple outputs will allow for greater flexibility in routing, creating multiple mixes for monitoring/cues, utilizing hardware inserts for outboard gear, and various other uses.

There are two other common inputs and outputs found on current interfaces and these are; ADAT optical (Lightpipe) and S/PDIF (Sony/Philips Digital Interface). Both are digital and each has its own unique connector and number of channels it can transmit. An ADAT connection can carry up to eight channels of digital audio each way while S/PDIF carries two each way. A common use for the ADAT protocol is that of expansion. There may come a time when your current interface is incapable of handling the load of a session. If and when this becomes the case, it can be relatively easy to add eight more channels of preamplifiers that will communicate with your current audio interface via ADAT. Some common uses for the S/PDIF protocol might be to add a dedicated digital-to-analog converter for monitoring purposes or maybe adding vintage effects processors or CD burners (yes, they still exist) into your setup.

MIDI, and not over USB? Yes. This is a thing and that’s exactly why standard 5 pin DIN MIDI ins and outs still exist. The synth market is massive and growing, and a large part of this market is the used segment. MIDI over USB didn’t start to gain momentum until the aughts, so before that nearly everything incorporated the standard 5 pin DIN connection. Most devices today still incorporate the standard connection even if MIDI over USB is present.

Scarlett Solo Front-Single Mic (XLR) input and 1/4” line/instrument input and headphone output

Scarlett Solo Rear-USB connection, right/left stereo RCA outputs, and a Kensington lock

Scarlett 18i20 Front-two dual XLR and/or 1/4" instrument inputs, mic preamp gain trim pots, meter bridge, monitoring controls and headphone outputs with volume controls

Scarlett 18i20 Rear-six dual mic (XLR) and/or 1/4” line inputs, word clock out, MIDI in and out, S/PDIF in and out, ADAT optical in and out, and ten 1/4” analog outputs

What are all of these numbers and stuff?

When examining the features and specifications of audio interfaces, the novice might soon be turned off by all the symbols, numbers, and other terms which can make the task even more daunting. Don’t let this scare you! These figures are there to let you know about the performance of the device and how much resolution you will ultimate get from your interface.

The sample rate and bit depth are probably the most important of the lot. I’m going to simplify this as much as I possibly can, so here goes. The bit depth or word length has a direct correlation to dynamic range (loud to soft). The most common bit depth is 16 bits, and this is on account of the Red Book CD standard which went into effect in 1980. Every CD ever manufactured has been produced at 16 bits and with a sample rate of 44.1kHz; audio at this resolution is everywhere! Today most interfaces are going to operate at 16, 24 and some at 32 bits. So what does this mean? Greater dynamic range, clarity, and depth of field as you increase the bit depth. The sample rate determines the highest frequency that can be recorded. The higher the sample rate, the greater the harmonic content that will ultimately be recorded. This lends itself to a richer, more precise recording if the proper parameters are in place.

The bit depth and sample rate are going to change (or possibly not) depending on what type of music, or content that is being recorded. Classical music is going to demand the highest bit depth and sample rate, while rock and pop might not be as fickle. Ultimately this is going to depend on the user/engineer and what they feel is best.

Other specs that one should consider are; how much gain does the preamplier(s) offer, phantom power (48 volts) for condenser microphones, mic preamplifier pads for hot signals, low-latency monitoring and noise/distortion that’s inherent in the unit.

So what else is there?

Some interfaces offer processing on-board and/or in-line which allow for plugins to be instantiated during the recording and mixing process; this also reduces the load on the host computer. There are also a handful of interfaces that are platform specific and will only work in tandem with a Macintosh or Windows based computer. If you have more questions, feel free to reach out an we can help to steer you in the right direction!