M-Audio Profire Lightbridge

Boring can be bad — like synthesizers that use the same architecture Bob Moog hit upon 35 years ago, a guitar that’s the 9,475th knock-off of a Fender Stratocaster, or movies featuring pop stars. But boring can be good — very good — when you’re dealing with Things That Connect to Computers. Concerning an audio interface, you want to set it up, plug it in, then forget that it exists.

Which brings us to the delightfully boring ProFire LightBridge (Figure 1), a FireWire 400-to/from-ADAT lightpipe bridge that handles 32 channels at 44.1/48kHz or 16 channels at 88.2/96kHz. It’s cross-platform, and incorporates:

  • ASIO, Core Audio, WDM, and GSIF II drivers
  • A headphone out with dedicated level control
  • Balanced 2-channel 1/4" outs with level control
  • Four ADAT in optical connectors and four ADAT outs
  • Basic front panel indicators for lightpipe and MIDI activity, sample rate, and sync
  • A multipin connector with an appropriate breakout cable that accommodates MIDI (including MIDI Time Code and MIDI machine control over two DIN 5-pin jacks), word clock on dual BNC connectors, and S/PDIF I/O with dual phono jacks.

If you want more specs, that’s why websites were invented — so check out www.m-audio.com. What they don’t tell you is that this is a sturdy box with a substantial feel, and is sufficiently compact that it will sit politely in a corner of your desktop as it dutifully shuttles audio back and forth between your computer and lightpipe-compatible devices.


First up: installation. I elected to subject a dual G5 Mac to this process, because frankly, it’s a magnet for FireWire issues and I figured if the LightBridge worked on this, it would work on anything. I went to the M-Audio site to download the latest drivers (always a good idea; Windows fans, note there are drivers for Vista 32-bit) and installed them. Kudos to M-Audio for warning you to turn off your computer before connecting the device.

Upon power-up with the LightBridge connected, the computer emitted an intermittent, high-pitched sound whenever the main hard drive did disk access. This had happened with almost all other FireWire devices I’ve connected, so I turned off “Allow Nap” under Apple Menu > System Preferences > Processor (this requires downloading and installing the CHUD utility from the Apple website; for details, see “The Software Power User Guide” in the 9/07 EQ) and as with the other devices, the problem went away.

Then things started to get boring. I went to the Mac’s Audio MIDI Setup, and yup, the interface was there. Part of the driver installation process deposits a control panel applet (Figure 2) where you set things like sync source, active ins/outs, and the like; it also worked as expected. So I hooked up my venerable (and still wonderful) Panasonic DA7 mixer, then booted up MOTU’s Digital Performer 5 to see if all was well in audio-land.

I tried syncing the DA7 to the LightBridge: Check. Vice-versa: Check. Send audio to Digital Performer and record it: Check. Route the recorded audio from Digital Performer back to the DA7: Check. Sync LightBridge to DA7 word clock: Check. Sync DA7 to LightBridge word clock: Check. Try S/PDIF: Check. Monitor output: Check (and there’s a decent amount of headphone level). Observe lights on front panel: Check.

By this time, I was getting pretty bored so I thought I’d liven things up by transferring eight tracks of audio (courtesy of Sonar) in my Windows machine through my Creamware SCOPE card’s ADAT out to the LightBridge’s ADAT in, and thence into Digital Performer. Check. As a last resort to try to find something to complain about, I lowered the sample buffer down to a CPU-straining 64 samples. That worked fine, too.


The ProFire LightBridge does exactly what it promises to do, and does so with zero fuss. It’s easy to install, easy to use, and I don’t even have to make a subjective value judgment about converters because it’s all digital — and if there’s any jitter, I sure can’t hear it.

So the bottom line is simple: File under “boring can be good,” because — thankfully — the LightBridge is both.

Product type: ADAT lightpipe to/from FireWire interface converter.

Target market: Those needing to interface ADAT lightpipe-compatible devices (mixers, converters, mic pres, etc.) with computer-based systems.

Strengths: Accepts/outputs 32 channels of ADAT lightpipe I/O and two channels of coax S/PDIF I/O. Additional stereo analog line out and headphone out. Cross-platform. Includes 4-pin to 6-pin and dual 6-pin FireWire cables (each six feet long). Good documentation.

Limitations: Nothing significant.

List Price: $499.95



When Alesis introduced the ADAT digital multitrack recorder, it came with an unusual digital audio interface: a thin, somewhat sexy fiber-optic cable capable of handling 8 channels of 48kHz/24-bit audio. This provided an elegant, inexpensive solution for transferring audio, as it didn’t require a multiconductor cable with esoteric (read: expensive) connectors.

As the ADAT juggernaut marched across the world of recording, other devices incorporated ADAT interfaces to hitch a ride on its popularity. The digital mixer was a logical candidate, as you could pipe the output from the mixer directly into the recorder for tracking, or send signals from the ADAT to the mixer while mixing. Then came audio interfaces, which usually incorporated a lightpipe interface to accept and/or send the signal from ADATs; AD/DA converters also tended to favor lightpipe interfacing.

By the late ’90s, the ADAT was well on the road to extinction, having been bested by cheap computing power and world-class digital recording software. But the ADAT interface refused to die. It adapted to the 88.2/96kHz world by using multiplexing (SMUX) technology to send four channels of high-resolution audio over the standard 8-channel hardware, and new product categories elected to go lightpipe — such as octal mic preamps that fed into audio interfaces.

What’s more, the ADAT interface doesn’t seem destined to go away any time soon. Its main competitor at the time, TASCAM’s TDIF interface (which was based on multiconductor cable) is now an historical footnote, and MADI (a promising 56-channel interface) hasn’t really gotten any traction other than in high-end applications.