Better Mobile Audio
Craig Anderton takes a look at the four basic pathways between an audio interface and your laptop
The LiveBook includes on-board audio in the form of the industry-standard AC97 audio chip and a built-in mic (you won't record a symphony orchestra with it, but it's handy as an audio notepad). The AC97 is actually quite capable, and can even do surround playback; but if you want quality mic preamps, XLR inputs, digital I/O, MIDI, and other necessities of modern computer-based music recording and editing, you're going to have to think "outside the box" with an external interface.
There are four basic pathways between an audio interface and your laptop: USB 1.1, USB 2.0, FireWire (IEEE-1394), and CardBus (PCMCIA). Interfaces are available at just about any price point, but generally, the more you pay, the more you get. Companies in the USB/FireWire interface business include Alesis, Apogee, ART, Behringer, Digidesign, Edirol, E-Mu, ESI, Focusrite, IK Multimedia, Lexicon, Line 6, Mackie, M-Audio, Metric Halo, MOTU, PreSonus, RME, Tapco, TASCAM, and Yamaha (and I'm sure I left quite a few out!) - so you definitely won't feel that your choices are limited.
Note that USB and FireWire interfaces may be suitable for desktop use, laptop use, or both. One differentiating factor for mobile recording is whether the interface can be bus-powered, or requires an external power supply. While bus-powered devices are convenient for field use, they may not have all the bells and whistles of multi-channel, AC-powered interfaces. Bus-powered devices also get their power from the laptop's battery, which shortens the run time you can get from a charge.
You also need to analyze your needs carefully. For example, some audio interfaces contain MIDI in and out, others put MIDI I/O on a breakout cable, and others don't have any MIDI interfacing at all. If you plan only on audio recording and playback, MIDI is likely not necessary. But for live performance, you may find it essential.
PCMCIA (CardBus)
A CardBus interface ties in the closest with your computer's innards; it's the laptop equivalent of putting a PCI or PCIe card inside a desktop. Let's look at some representative products to get an idea of what's available.
A basic PCMCIA interface, like the Indigo made by Echo, provides high-quality audio inputs and outputs with low latency. Moving further up the interface food chain, Digigram's VXpocket 440 offers four balanced mic/line analog ins and outs (although the number you can actually use varies with the sampling rate and bit resolution), stereo mini-jack for headphones, and coaxial SPDIF in/out. Among the I/O, available via a breakout cable, is a phono connector for LTC (Linear Time Code) input. This is an important addition for those involved in remote recording for film productions.
A PCMCIA interface provides high-quality audio inputs and outputs with low latency
E-Mu's 1616m is a high-end PCMCIA-based device with two parts: A card that can provide a high-quality audio output (but not input) for your laptop, along with a separate audio "dock" that connects to the card via a cable. The dock acts like a breakout box, with a plethora of I/O - pro-level mic preamps, multiple ins and outs including XLR connectors and digital I/O, and even a turntable input suitable for DJ applications.
E-Mu's 1616m "audio dock" connects to a companion PCMCIA card via an Ethernet-like cable, thus greatly expanding the I/O options.
Finally, the RME CardBus takes a different approach altogether. It's designed to be used with the RME Digiface and MultiFace I/O boxes, which usually hook into a PCI card; the CardBus basically replaces the PCI card. Relying on a card bypasses any of the performance issues associated with USB and FireWire.
USB 1.1
USB 1.1 interfaces are basic devices with limited bandwidth. They're a compact and economical solution if you simply need to get two to four channels into your computer, with two channels for monitoring (although at 88.2kHz and 96kHz sample rates, you may be limited to only two channels of recording or playback). Furthermore, the latency is typically higher than FireWire or USB 2.0 interfaces. These are made by a huge number of companies; there are even specialty USB interface devices, like USB mics and even USB guitars.
USB 2.0
Although there are few commercially-available USB 2.0 devices, they offer much higher bandwidth and lower latency than USB 1.1 boxes; their performance is essentially equivalent to FireWire devices.
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Author
Craig Anderton has played on, produced, or engineered over 20 major label releases. He is currently Editor in Chief of Harmony-Central.com, Executive Editor of EQ magazine, and performs in the band EV2 with Brian Hardgroove from Public Enemy. He has also lectured on technology and the arts in 37 states, 10 countries, and in three languages.