Photos: Mark Ewing
When Mackie introduced their Onyx mixer range, the mixer's newly designed mic preamps attracted a lot of favourable comments. These preamps appear to have been designed to subtly flatter the sound in the same way that many of the popular vintage preamps do, while offering a wide dynamic range (123dB) and very low distortion (0.0007 percent THD). When I reviewed the Onyx mixer, I was particularly impressed by the sense of clarity and detail these preamps presented, and they come very close in performance (both subjectively and technically) to some of the extremely expensive and esoteric boutique mic preamps currently available. The Onyx mixer also had a Firewire option allowing it to be used as an audio interface to computer music systems, so it wasn't entirely unexpected when Mackie announced a stand-alone Firewire interface based around their Onyx preamps.
Housed in a conventional 1U rack case and requiring only Firewire 400 connectivity to hook up to a computer, the Onyx 400F comprises four Onyx mic/line preamp channels augmented by four further line-only channels, where the mic/line channels also benefit from analogue insert points on TRS jacks. Next-generation AKM 24-bit/192kHz A-D and D-A converters are used to maintain the audio quality of which the Onyx preamps are capable. There are eight balanced line outputs, S/PDIF stereo digital I/O (coaxial), and word-clock I/O on conventional BNC connectors. Unlike some competing products, though, there's no ADAT I/O, which rules out adding more I/O channels without adding another interface. (Multiple interfaces can be used together on Mac OS X 10.4, and Mackie are working on this capability for Windows). According to the spec, special DSP tweaks enable particularly fast audio transfer, and hence lower latency.
Both Mac OS and Windows are supported at 24-bit resolution only and at up to 192kHz sample rate. Both the analogue and digital I/O can be used together for a maximum of ten simultaneous inputs (mixed to five stereo pairs) and all 10 outputs from the DAW are routed directly to the 10 physical output jacks of the 400F when the integral DSP mixer is switched off. The DSP mixer just alluded to is a 10 x 10 DSP device that can route any input directly to any output with negligible latency, and which can also be used to set up five different custom stereo mixes, making it ideal for monitoring. This mixer has the ability to save and recall settings, and uses 64-bit floating-point processing to maintain the best possible signal resolution. In effect, the use of the floating-point maths provides more mix headroom, which is particularly important when summing signals. However, it must be noted that this mixer can only mix the 10 inputs (eight line and two S/PDIF) plus the stereo DAW output — it can't be used to sum ten separate outputs from the DAW mix, which is perhaps missing a trick if the mixing engine is really that good. The mixer can also currently only output as stereo pairs.
When overdubbing, the 400F's dual headphone outputs provide both the engineer and performer with their own headphone feeds (both based on the control-room mix or the output 7+8 mix) with independent volume control. Those who do not need the extra capabilities of the DSP mixer can switch it off in the software, whereupon the 400F becomes a straight 10-in, 10-out audio interface, with all 10 inputs feeding ASIO or Core Audio streams 1-10, and DAW outputs 1-10 feeding the 10 output jacks on the back of the 400F.
In addition to its I/O capabilities, the Onyx 400F also functions as a monitor level controller and a single-port MIDI interface. The two independently adjustable headphone outlets are on the front panel, along with instrument input jacks for channels one and two. All the other connections are on the rear panel, where rear-panel combi jack/XLR sockets handle the mic/line channels and conventional balanced quarter-inch jacks take care of the line inputs and line outputs, including a dedicated stereo control-room output. This keeps the unit very tidy, but it does mean that if you want to switch between mic and line inputs on the first four channels, you need to be able to access the rear of the unit. Mains power comes in via the usual IEC socket, and there are two six-pin Firewire ports to facilitate device chaining.
The front panel is simply set out, with clean, stylish lines, and using green LED indicators to the left to show the clock source, Firewire status, and MIDI I/O activity. A single knob adjusts the control-room output level, with two further knobs to adjust the phones levels. Right of centre are the four mic/line input channels, the first two with switchable high-impedance instrument inputs on unbalanced jacks, and all four channels have simple four-LED level metering at -40dB, -20dB, -10dB, and Overload. A single 48V button applies phantom power to all four mic inputs when active.
Bundled with the Onyx 400F is a full version of Mackie's own Tracktion 2 Audio + MIDI sequencer (reviewed in SOS August 2005), which combines a practical level of flexibility with ease of use. Although the boxed retail version is bundled with extra plug-ins, the bundled version is otherwise identical as far as its sequencer section is concerned. Tracktion 2 is available for both Mac OS and Windows, though some Mac users may prefer to use Garage Band (bundled with all new Apple Macs), which is also relatively straightforward to use. The minimum PC computer specifications for running the Onyx 400F and the Tracktion 2 software are Microsoft Windows XP (SP1) or later running on a machine with a Pentium 4, Celeron, or Athlon XP processor. A minimum of 256MB of RAM is specified, though at least twice that would be desirable. Mac users must be running Mac OS 10.3.9 on a G4 or more powerful machine, again with at least 256MB of RAM.
The control settings for the Onyx 400F are handled via further software that comes with the unit. In addition to setting the sample rate and digital synchronisation source, you can set up the DSP mixer which makes it possible to create up to five stereo pairs of low-latency mixes at the outputs, based on the line and S/PDIF inputs and independent of the DAW software. The stereo DAW mix can also be added to the monitor mix. If not needed, the DSP mixer can be switched off, and the last setting is remembered even when the unit is not connected to a computer.
Because the 400F remembers the latest state of the DSP mixer when the console is off and the computer is removed, it can act as a stand-alone mixer or four-channel mic preamp. Suggested applications in this mode include using the 400F as an eight-channel line-level and two-channel S/PDIF rackmount keyboard mixer at a gig — all 10 inputs could be mixed down to stereo and routed out to a stage DI for the front-of-house mix, and this mix could also provide a personal monitor feed adjusted by front-panel Control Room level pot.
While it is possible to use the 400F as a four-channel stand-alone Onyx mic preamp, all four mics could optionally be mixed down to stereo for direct-to-stereo recording, so there's another stand-alone application. In the project studio, the user could leave his or her guitar preamps, keyboards, and mics patched in and mixed to stereo, making it possible to play or rehearse without having to switch on the computer.
The tabs across the top of the configuration software's main window select which output pair you're dealing with, and a simple level-pan mixer (with solos and mutes) appears below for setting up the mix for that particular output. It really is that easy — you just have to remember to switch off software monitoring in your DAW if you want to set up low-latency direct monitoring. And talking of easy, installation on a Mac was simply a matter up unzipping the installation archive and then selecting Onyx 400F in the driver setup section of the DAW software (Apple Logic Pro in my case). On Windows machines, ASIO, WDM, and GSIF are currently supported, but users are advised to check the Mackie web site for the latest driver and software versions. The first eight numbered inputs and outputs are the analogue connections, with the S/PDIF pair showing up as 9+10. A setup window enables the user to select the sample rate and clock source, and also lets you switch the headphones to mirror outputs 1+2 or 7+8.
Listening tests confirmed the Onyx preamps to be as clean and flattering as I remembered them, and undoubtedly the quality of the preamps is what will sell this unit against the competition. The LED metering reports overloads with a decent safety margin before digital clipping actually occurs, so to get a more exact idea of how much gain you need, it's best to consult the input metering in your DAW software. Arranging low-latency monitoring and custom mixes is extremely easy, but I can't help thinking that the ability to set up alternative monitor mixes might have been more useful if they could have been sent to the individual headphone outputs, rather than just to the main line outputs.
The only other real limitation is that of having no ADAT expansion slot for adding more I/O, as there are several very attractive preamp racks around now that use the ADAT interfacing standard. However, Mac users can employ Tiger's built-in Aggregate Devices to combine a couple of 400Fs, providing 20-in, 20-out capability with eight mic preamps. Although Mackie are working on updating the driver to allow daisy-chaining in Windows, they can't yet give an indication of when this will be ready. I would have liked to be able to use the DSP mixer for combining all 10 DAW signals, but maybe this will come in a future upgrade.
The MIDI ports worked with absolutely no fuss, and having insert points on the rear panel means you can hook up the unit to a patchbay if necessary, enabling hardware compressors, equalisers, and so on to be used while recording. I still can't see the need for 192kHz sampling unless you're using converters that cost more than your car, but at least it is supported for those people who think they need it. Offering only 24-bit recording isn't a problem, as modern DAW software invariably works best at 24-bit resolution and generally offers dithering down to 16 bits for audio CD burning. Where dithering isn't available, most DAWs will happily accept a 24-bit signal and truncate it to 16 bits.
I'm aware that this is turning out to be a rather short review, but that's because everything about the Onyx 400F is extremely straightforward, even the 'no brainer' software installation. I really like the Onyx preamps, which are probably worth the ticket price on their own, and the Firewire side of things works just as flawlessly as it did on the Onyx mixer. I think Mackie have got the configuration software about right, as it does most of what most people need to do with absolutely no fuss, and though you can't set up custom headphone mixes directly, you can set up a custom mix on outputs 7+8 and then mirror that. Even so, it might have been more useful to be able to directly route different custom mixes to the two headphone outlets.
With the DSP mixer off, Onyx 400F is a true 10-in, 10-out interface, and though many people now seem to mix directly to stereo within their DAW software, you can if you wish switch off the DSP mixer, route 10 tracks from your DAW to the 10 physical outputs of the box, and then patch those into the mixer of your choice. I have no hesitation at all in recommending the Onyx 400F in terms of audio quality and ease of use.