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M-Audio ProFire Lightbridge

We only bring this up so readers are aware that not just any audio interface hooked up to their computer can then be brought into Pro Tools M-Powered via Lightbridge.

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Studio, project studio

Key Features
32-channel ADAT I/O plus stereo S/PDIF to/from computer via FireWire; also handles high sample rates via S/MUX


M-Audio | 866-657-6334 |



  • Allows 18 track digital entry into the world of Pro Tools from any digital interface(s) via ADAT I/O
  • Permits 32 channel real-time interfacing between digital mixers and DAWs to save CPU load and/or mixer channels with any DAW software from any manufacturer


  • It requires Pro Tools M-Powered 7.3 for Pro Tools use with its maximum 18 input limit at any sample rate

This digital interface is an excellent bridging element for audio workstation usersThe M-Audio ProFire Lightbridge — a 34-in/36-out FireWire lightpipe interface — is quite literally a bridge between all our MOTU, RME, Apogee, etc. interfaces and Pro Tools M-Powered software, therefore it provides a quick and easy multiple multi-track entry into the Pro Tools world. Indeed, it allows you to hook up an elaborate multi-track setup and record directly into Pro Tools M-Powered 7.3 (and simultaneously into Digital Performer and Ableton Live 6.01) using various interfaces … while using no other M-Audio hardware whatsoever except this tiny (and inexpensive at $499) unit. [All devices used in Fred’s test setup are either stand-alone converters or operate in standalone mode. As such, they are not operating as audio interfaces. We only bring this up so readers are aware that not just any audio interface hooked up to their computer can then be brought into Pro Tools M-Powered via Lightbridge. Visit M-Audio’s website for more information. — Ed.]


And tiny, it is. Although nominally “half-rack” in size, the Lightbridge is even smaller than M-Audio’s FireWire 410 interface and measures only about 8 x 6 x 2 inches. The front panel has a headphone jack with associated level pot, a general level pot (with stereo DAC circuit) and 17 status LEDs showing sample rate, sync source, MIDI status, and lightpipe activity for input and output on the four ADAT I/O ports. Over on the right is a power pushbutton and associated blue LED. The rear panel is simple: four pairs of ADAT-ODI format (“lightpipe”) I/O connectors, a set of ?-inch TRS-balanced analog monitor outputs, a 6-pin FireWire jack, a 12VDC power connector (which mates with a cable from a hefty 1 amp line lump power supply) and then the DB15 connector which mates with an identical breakout cable from M-Audio’s 1010LT interface, supplying clearly labeled S/PDIF, MIDI and word clock I/O connectors.

The ProFire Lightbridge specifically allows the user to connect up to eight eight-channel lightpipe plastic fiber optic cables – each of which can contain eight channels at 44.1 or 48 kHz (or four channels at 88.2 or 96 kHz), plus a stereo coaxial S/PDIF I/O pair. All can be routed to and from any DAW application. Assuming they already own various ADCs and DACs, the user can “mix and match” to assemble an input (and output) system that integrates seamlessly with their DAW software. If the user only needs output for stereo monitoring, an external DAC should not be necessary: the ProFire Lightbridge has a built-in stereo DAC.

Then there’s the Pro Tools connection. Historically, one had to previously invest in high-priced Digidesign hardware to gain entry into this world. Avid acquired Digidesign about 13 years ago and soon introduced a lower priced, entry-level “LE” version of Pro Tools with its own dedicated hardware set. A few years ago, M-Audio joined the Avid stable and various lower priced M-Audio interfaces began to appear; one of these interfaces is required to work with the “parallel universe” version of Pro Tools LE known as Pro Tools M-Powered. But even the most sophisticated of these interfaces (such as the FireWire 1814 or the ProjectMix I/O) contained only a single ADAT I/O set and supported only eight channels of ADAT I/O; at the highest possible sample rate, four channels of optical I/O were supported. Further, Pro Tools M-Powered recognizes only one interface at a time.

Now, a real sea change has occurred. The ProFire Lightbridge, makes it possible to connect several ADCs and DACs from any manufacturer to M-Powered Pro Tools.

In Use

For this test, I locked all converters to a Rosendahl Nanosyncs reference clock. For converters — tracks 1-8 — I used my standard mixer, the Crane Song Spider, set to lock to the 88.2 kHz clock from the Nanosyncs, and connected various mic sources to its first four channels. From its first set of ADAT outputs at 88.2 kHz (channels 1-4), I sent a high-quality plastic fiber optic cable to the ProFire Lightbridge ADAT input #1, and immediately saw “activity” on its first green LED — a good sign! Getting to the second ADAT input was a little more difficult. I already had a pair of vintage vacuum tube AKG C60 mics over a Mason & Hamlin piano. These mics go into a pair of Manley MicEQ500 mic preamps, which feed the first two channels in a Genex GXA8 ADC unit. But, as that box doesn’t do S/MUX, I had to first send its AES/EBU output into a RME ADI-192 converter, which turned it into that. I then sent the RME’s S/MUX output to the ProFire Lightbridge and its second LED started flashing. Yes!

Working in a testing mode I didn’t attempt to fill up all the inputs in my preamps and converters. What I did assemble I routed through the ProFire Lightbridge to a little “Mac-tel” Mini! And, believe it or not — maxed out with RAM and with its CPU resources tweaked — the Mini was able to run all 18 channels in Pro Tools, Digital Performer and Live simultaneously (at 88.2 kHz) to do this test! Anyway, for the third ADAT input into the Lightbridge, I connected a Apogee Trak2, which can send its own stereo feed via S/MUX. A C24 fit the bill perfectly as input source and, again, rang the bell on the M-Audio interface.

For the final ADAT input, I went to my MOTU 896HD which — being from the previous generation of MOTU’s development cycle — sends only channels 1-4 via S/MUX on its sole lightpipe output. But when I connected a pair of Gefell M930s to channels 1 and 2 and a fiber optic cable to the appropriate port on the Lightbridge, the fourth green M-Audio signal presence LED started flashing.

I first set up the Pro Tools M-Powered session (note that the Lightbride requires version 7.3). Once I had configured the I/O matrix properly, made the requisite number of new mono and stereo tracks and clicked them into record, everything worked and I heard every single mic I had set up coming through the monitors … and it all sounded great. So yes — the Profire Lightbridge works as advertised and, what’s more, it worked the first time I tried it. I was able to monitor 16 track outputs via a Genex GXD8 DAC (fed from ADAT output #1) and the 8-channel ADAT card in an Apogee Trak 2 (fed from ADAT output #2) as well as a stereo software mix via the ProFire Lightbridge’s own coaxial S/PDIF output.

I also ran Digital Performer and Live 6.01, and every time I upped the inputs in the M-Audio control panel, each of those applications updated its input list and I was able to record everything I recorded in Pro Tools into the other programs, as well.

Thus, the bottom line is that this tiny M-Audio box enabled me, for the first time in my life, to connect every interface I had in the studio to every DAW software application I use. Everything worked perfectly the first time!


I think this is one of most important digital audio products of 2007. Now the relatively closed world of Pro Tools M-Powered has opened up to allow the use of multiple non-M-Audio multi-track digital interfaces.