Choosing an Audio Interface

November 1, 2010


The more things change, the more they stay the same; that''s the cliché, right? True at times, but when it comes to the way audio is routed throughout a radio facility, the cliché is wrong. AoIP wasn''t even a dream 15 years ago, and there have been many advancements made as of late in how we get audio in and out of a computer.

Do a little

Yellowtec PUC2

Yellowtec PUC2


How to choose an audio interface mostly depends on needs. How complex is your audio routing scheme? If a facility simply broadcasts a digital play list all you''ll need is a connection between the hardware that houses the audio files (and hosts the software that helps you compile the play list) and your audio console. Firewire, USB, AES, it doesn''t really matter.

Tascam US-2000

Tascam US-2000


Looking a little deeper, one of the great developments in audio technology has been the democratization of quality converters. It''s no longer necessary to spend tons of cash to get converters that can output digital signals up to 96kHz or even 192kHz. Manufacturers of high-end equipment will tout the design of their input stages and the ability to output a balanced signal over long cable runs, for example, and with good reason. For many real-world applications, however, the most popular audio interfaces at all price points will do a good job.

Tascam US-800

Tascam US-800


As for the choice between Firewire, USB or AES connectivity, all of these protocols will deliver audio of equal quality; the robust construction of AES cables (especially when compared to the Alesis ADAT connections that were a popular alternative a decade ago) leads many radio professionals to gravitate toward this format. If you need AES inputs from a piece of equipment that has AES outputs only, and the ability to route an interface to a console via Firewire or USB, purchasing an interface with multiple connections will not bust the bank.

Alesis iO2 Express

Alesis iO2 Express


If you're looking for plug-and-go technology, USB interfaces offer convenient options. Yellowtec's PUC2 is a USB-powered sound card with digital and analog audio interfaces. This AES-3 device delivers 24-bit/192kHz performance. It's modular design gives the option to connect to a variety of interfaces, including analog line input/output and a microphone interface.

The US-2000 from Tascam is a 16-input audio interface condensed into 1RU. It features eight studio-grade mic preams, with two mic inputs on the front panel. An additional six balanced 1/4" line inputs are provided, as well as four balanced line outs and stereo digital I/O. This interface comes with Cubase LE4, a 48-track workstation for Mac or PCs.

For laptop users, Tascam's US-800 is a lightweight, multichannel recording interface that offers eight inputs and four outputs. Six XLR mic inputs feature phantom power and 192kHz/24-bit audio converters. It also includes S/PDIF digital audio/MIDI I/O.

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Do a lot

AudioScience ASI5680

AudioScience ASI5680


If a facility does more – record voice-overs, create music beds by cutting, pasting, and time compressing music library files, for example – then the choice is more selective when it comes to audio interfaces. Of course, the first decision has to be the workstation itself. It''s hard to believe that less than 20 years ago you had to cough up $100k or so to get the recording and editing capability that any of the current off-the-shelf Macs or PCs leave in the dust.

AudioScience ASI5211

AudioScience ASI5211


Let''s say you''re charged with recording voice-overs. You know that Pro Tools has become the de facto recording platform for the video and recording industries, but why spot the cash for the full program when Pro Tools LE – the free version that DigiDesign provides with the hope that it will entice users to buy the complete program – has all the features needed to do the job?

Lynx AES15e

Lynx AES15e


In this case all that is needed from an audio interface is a couple of analog or microphone inputs, and a pair of stereo inputs and outputs, either digital or analog. Even if analog might do the trick, why not spend the extra couple of bucks and get an interface with both sets of outputs. Audio will need to pass through digital connections at some point. This identical scenario applies for Adobe Audition, Samplitude from Magix, or any of the other popular software front ends for a DAW. Be careful though, some of the older proprietary programs designed for radio are not as careful about upgrading drivers. You don''t want to purchase a screaming new quad core i7 Windows 7 machine only to discover that your software hasn''t migrated beyond Windows XP.

Digigram LoLa

Digigram LoLa


When it comes to PCIe cards, AudioScience has two options for analog/digital audio. With the high channel count ASI5680 PCIe audio adapter with eight stereo playback streams fed to eight stereo outputs and one stereo record stream fed from one stereo input, users can mix and route anything to anywhere.

AudioScience also created the ASI5211, a PCIe version of the ASI5111 card. It removes time-critical audio processing burdens from a PC, featuring two stereo record streams fed from either a balanced analog input or an AES3 digital input, four stereo play streams mixed to both a balanced analog output and and AES3 digital output, and a mic input. The analog I/O level has been increased to +24dBu, a noise gate added and GPIO adds two opto-isolated inputs and two normally open relay outputs.

Lynx Studio Technology's AES16e-50 PCIe card offers multiple connectivity options. In addition to 16 channels of 192kHz AES3 digital I/O via its two D-sub ports, it has 32 digital I/O channels using AES50 technology, which provides point-to-point connection for multi-channel audio and system control over a single CAT-5e or CAT-6 cable.

LoLa from Digigram is a low-latency sound card platform for logging and multi-channel recording. Main features of the first LoLa product (the LoLa280) include eight line-level inputs, two line-level outputs and an optional eight-channel mic pre-amp in a 1RU package. It also includes a built-in mixer with automatic gain control and a software control panel.

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Outside the box, or in?

This leads us to a question: Whether ‘tis best to think outside the box or stay within its confines. Is it better to purchase (or stick with) a PCI or PCIe card-based audio interface or move over to a stand-alone interface? Of course, the walls break down a bit, since many PCI and PCIe interfaces have break-out cabling that increases the I/O capabilities and adds additional features (a mic pre, perhaps).

Six or so years ago adding audio capability to a Mac or PC, meant using PCI – it was the only game in town. This was a fine option if you needed a stereo pair of digital ins and outs. PCI systems are largely legacy products at this time, however. If you have an interface that uses this technology and are thinking of moving to a new computer, make sure drivers are available for the operating system – there''s a good chance they''re not available.

PCIe offers much more bandwidth than older cards. In a few years we should see PCIe cards that are faster than their forebearers, with even more bandwidth. But to pass 16 channels of audio with a card-based system, a number of PCIe audio interfaces are available that will serve quite well.

If connectivity requirements exceed more than a single mic pre and pairs of analog inputs and outputs it would be wise to consider an external hardware unit. USB and Firewire have both achieved speed and bandwidth that allows them to compete with PCIe cards, and these devices can be purchased in an almost unlimited array of configurations.

Ethernet and an all-digital pathway, from production to transmission, may be a reality that is ubiquitous in the near future. But as long as the human voice is part of the equation, microphones and interfaces that can input their signals will be a part of the chain. A wide array of audio interfaces is available so assess input and output needs and bandwidth requirements and have fun!

Eskow is a composer and journalist who lives in central New Jersey. He is a contributing editor for Radio magazine's sister publication Mix magazine. Thanks to Chris Ludwig of ADK Pro Audio for his input.


Resource Guide

Manufacturers of sound cards and audio interfaces

  • AudioScience
    302-324-5333
  • Digigram
    703-875-9100
  • Lexicon
    781-280-0300
  • Lynx Studio Technology
    714-545-4700
  • Mackie
    800-898-3211
  • Prism Sound
    973-983-9577
  • Roland
    800-542-2307
  • Tascam
    323-726-0303
  • Yellowtec
    +49 2173-967 30


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