A Mmultichannel mic pre and Lightpipe master clock.
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FIG. 1: The PreSonus DigiMax FS provides front-panel access to its input connectors, gain controls, and sync options.

PreSonus has channeled its knack for designing preamps and handling digital conversion into the DigiMax FS, an 8-channel mic preamp with some interesting sync capabilities. It doesn't interface with a computer directly — there are no USB or FireWire ports — but if you have an interface with ADAT Lightpipe connections, such as Digidesign's 002 digital mixer, the DigiMax FS can serve as a high-quality expander for more mic inputs.

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Click here for product specifications on the Presonus DigiMax FS mic pre and Lightpip master clock.

On top of that, the DigiMax FS has extensive analog insert and output options, making it very useful as an independent mic pre that can feed an audio interface in a budget home studio. For the semipro or pro studio with unused Lightpipe-equipped devices, the DigiMax FS can serve as a high-quality clock source.

Combo Deal

The DigiMax FS provides eight Class A preamps, which you access through Neutrik combo connectors on the front panel (see Fig. 1). Although some users may not care for the idea of a 1U mic pre with all its XLR connections on the front panel, the multitude of rear-panel jacks makes it obvious why this design was necessary. Users who install the DigiMax FS in a rack will probably want to keep at least a 1U space free above the unit for mic cables entering the rack from the rear. (There are no controls directly above or below the inputs, so cables don't get in the way when you're operating the unit.)

Inputs 1 and 2 are configured for instrument level on the connector's TRS jack. The rest of the ¼-inch inputs are set for line level. (You can use the rear-panel insert jacks to feed line-level signals to inputs 1 and 2.) To the left of the input connectors are two rear-illuminated buttons that let you assign phantom power to inputs 1 to 4 and inputs 5 to 8.

To the right of the input connectors are gain pots for the eight inputs. The pots have markings for both mic and line gain ranges (0 to 60 dB and -20 to +20 dB, respectively). The controls are staggered, which makes them easier to grasp and operate. LED clipping indicators sit to the side of each pot.

At the right edge of the front panel are a power button and two buttons for setting up the unit's sync configuration. An Internal Clock button cycles between 44.1, 48, 88.2, and 96 kHz settings. An External Sync button changes color when pressed: red for ADAT sync and blue for synchronizing via the unit's rear-panel BNC connectors. Sync is internal when the button isn't illuminated.

To the Rear and Out

PreSonus has provided a wealth of analog outputs on the DigiMax FS's rear panel (see Fig. 2). For starters, there are eight TRS outputs marked DAC that are fed directly from the Lightpipe inputs. Because all connections are active at all times, you could use these to, for example, process Lightpipe tracks (say, from an archived ADAT tape) through analog effects devices while also passing the original digital versions to a separate DAW.

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FIG. 2: A multitude of analog outputs, including preconverter insert points, makes the DigiMax FS a serious front end for studios with ADAT Lightpipe connections.

Another section of the DigiMax FS's rear panel supplies eight direct outputs from the unit's input channels. A set of eight insert points (ring equals send) completes the analog output section. This is the perfect way to add compression or other effects to signals from mics or instruments before the signals are digitized.

On the left of the rear panel are BNC in and out connectors with a 75Ω termination switch, which can be engaged on the final DigiMax FS in a chain. You can add as many of the units as you like to create additional input and conversion capabilities.

Alongside the BNC section is the 96 kHz ADAT-SMUX section, which provides four Toslink connectors, two each for input and output. Standard ADAT devices (up to 24-bit, 48 kHz resolution) use the first connector in each section for all eight channels of input or output, whereas units capable of higher sampling rates and with SMUX implementation use the first connector for channels 1 through 4 and the second for channels 5 through 8 in each section.

Sync City

What should make the DigiMax FS attractive to studio owners with older Lightpipe-equipped devices is PreSonus's new JetPLL technology (Jet stands for Jitter Elimination Technology). JetPLL was developed by TC Applied Technologies (a division of TC Electronic), and the technology is part of the DICE II chip, which is used in TC Electronic's Konnekt 24D and PreSonus's new FireStudio audio interfaces.

The promise of JetPLL is that any incoming digital source will be adjusted to the same jitter spec as the device with JetPLL, no matter which unit is set to be the master clock. This should also provide better performance from the unit's converters, along with faster locking and rock-solid synchronization. Owners of units like Digidesign's 002 and 002 Rack, Yamaha's DM-series digital mixers, and RME's recording interfaces, as well as of older devices with early Lightpipe implementations, will benefit from reduced jitter.

In Session

I have been a fan of PreSonus's economical yet high-quality mic preamps for years but had not tried out one of its multichannel units. It's been a long time since my studio used any Lightpipe-equipped devices, but I have been doing some old-school analog processing and dumping tracks into MOTU Digital Performer 5 on my dual-processor Power Mac G5. I connected the direct outs of the DigiMax FS to my interface, a FireWire-equipped Mackie Onyx 1620 mixer. I used the aux ins of the 1620 to avoid problems with gain staging that could have occurred had I plugged the analog outs into the Mackie preamps.

The DigiMax FS preamps sounded very clean, especially with large-diaphragm condenser mics, and they gave me plenty of headroom on all channels. The instrument inputs worked well with several guitars I plugged into them, and the unit's insert points were able to drive a couple of different guitar processors without introducing audible distortion. Without even testing the unit's DAC or sync capabilities, I was very impressed with the DigiMax FS's audio quality and PreSonus's consistently good approach to preamp design.

For further testing, I took the DigiMax FS to a colleague's professional studio, where he had occasionally used a Digi 002 rack unit in a composing room for writing and recording projects when his extensive Pro Tools HD rig wasn't needed. We set up the DigiMax FS as the master clock for a session feeding instrument mics to a Pro Tools LE project. The DigiMax FS found sync faster than any external unit I'd seen set to master clock and driving a digital mixer. Best of all, there were no surprise noises or pops as we experimented with different bit and sampling rates. The DigiMax FS worked like a charm in this situation, and its converters sounded very, very good at high sampling rates with quality mics on instruments like acoustic guitar and solo violin.

To the Max

Although the average home recordist will probably be more interested in one of PreSonus's multichannel audio interfaces for all-in-one convenience, the studio owner who wants to make use of unused Lightpipe connections to add extra channels to a DAW (or even a full analog) recording setup should give a listen to the DigiMax FS. Its mic preamps alone make it a solid, midpriced front end for such systems, and its converters will probably outperform all but the highest-quality vintage Lightpipe units (like the ones that recorded all those ADAT tapes you haven't transferred yet). If Lightpipe is still your plumbing of choice, the DigiMax FS is an excellent way to beef up the digital signals flowing through the tubes.

Rusty Cutchin is a former editor of EM and a producer, engineer, and music journalist in the New York City area.

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Click here for product specifications on the Presonus DigiMax FS mic pre and Lightpip master clock.



multichannel mic preamp



PROS: Very good mic preamps. Multiple analog outputs. Preconverter insert points. Exceptional clock-sync technology.

CONS: Front-panel mic connectors.