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MOTU PCI 424 - EMusician

MOTU PCI 424

Card &Audio Interfaces: A complete I/O system for recording and mixing
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Back in 1998 when MOTU released the original 2408 digital audio interface, computer-based multitrack recording hadn’t yet caught on. At the time, MOTU’s foray into desktop music production hardware was forward thinking and, dare I say, revolutionary? Until then there weren’t many professional audio I/O choices available for native host apps, and the 2408 offered more bang for the buck than anything else on the market.

It wasn’t long after the 2408 hit the streets that MOTU added several audio boxes to their lineup that collectively addressed just about every need a studio might have — whether you wanted lots of analog inputs, lots more digital I/O, or sweet-sounding hi-res A/D/A conversion, MOTU had an interface that could deliver.

One appealing factor was that all of the interfaces connected to a single PCI card for a total of 72 input and output channels, and any combination of three boxes could be snapped onto the card to create a flexible I/O solution.

This concept has obviously been a success. Over the years, as sample rates and bit-depths increased and converter technology improved, MOTU rolled out updated hardware to keep up with the changing times. And still, the concept of MOTU’s PCI-based interfaces remains the same — why mess with something that works?
That’s not to say MOTU hasn’t raised the bar yet again. Their latest hardware offers a few key enhancements that are sure to find favor with golden ear audiophile-type engineers and bedroom-recording musicians alike.

Overview
MOTU sent all three of their new interface for this review, so I’ll look at them collectively as an entire system, pointing out highlights of each box along the way. But I’m getting ahead of myself.

Let’s rewind a bit and cover the basics: A core system consists of two hardware components — a PCI-424 card and a rackmount audio interface. These are connected via a single AudioWire cable (it’s actually a standard FireWire cable, but MOTU uses a proprietary format). There are three interfaces to choose from: the 2408mk3, the 24 I/O, and the HD192. A core system can include any one of the interfaces; additional I/O units can be purchased as expansion options. In addition, “legacy” (i.e., discontinued) interfaces such as the 1224 can be connected to the 424 card, which means you can mix and match among a range of I/O options and expand the system to fit your studio’s budget and growing needs.

2408mk3. As its name implies, the mk3 is the third incarnation of the now “vintage” 2408. Like the original, the mk3 has connectivity options up the ying-yang. Audio inputs and outputs are arranged into three banks, each of which can be set up to access one of four I/O formats: 8-channel TDIF, 8-channel ADAT lightpipe, eight channels of analog, and stereo S/PDIF. Each of its banks is configurable, so you could, for example, assign bank 1 to the analog ins and outs, set bank 2 to TDIF for interfacing with a similarly equipped digital mixer, and set bank 3 to accept eight channels of lightpipe from another computer running GigaStudio or some other virtual instruments.

There are two ways you can work with the 2408: It can serve as the audio interface with whatever compatible host software you choose, or, when the computer is off or detached from the 424 card, the 2408 can be used as a stand-alone format converter. Back when digital multitrack tape machines were all the rage, this was an important feature, as it provided a hassle-free way to transfer from ADAT to TDIF, or vice versa.

Sample-accurate sync has always been part of the 2408’s repertoire, but what’s new to the mk3 is that any analog input or the dedicated S/PDIF input can accept video or SMPTE timecode, and, provided your host program has the ability to sync to SMPTE via the audio interface, the sequencer can be controlled from a 3/4" video deck or some other analog deck, for example, without having to use a MIDI interface that supports SMPTE. (Currently, only Nuendo/Cubase SX and Digital Performer support this.)

Along these lines, SMPTE timecode can also be generated from any of the analog or digital outputs, making it possible to stripe tape without a dedicated timecode box. (It won’t burn the timecode onscreen, however.)

24 I/O. First there was the 24 I, which had plenty of inputs, but only a stereo monitor out. The 24 I/O adds 24 outputs to the mix, of course. This many ins and outs (all balanced 1/4" TRS, by the way) might seem like overkill at first, but there are some obvious applications. You could, for example, take digital audio tracks from a computer into the analog domain by feeding the outs into a 24-channel analog mixer.

The TRS jacks can be switched in groups of eight via software to operate at +4 or –10, which is handy if you work with a combination of pro audio and “semi-pro” gear. Nice.

Metering is the same as on the mk3 — 5-segment LEDs are provided for each analog channel. In practice, I found the meters easy enough to read and gauge levels from a distance of ten feet, give or take, but for more accurate readings I would rely on software meters.

There isn’t much more to say, other than there aren’t separate word clock in and out BNC connectors as there are on the mk3. The 24 I/O gets away with a single BNC that can be used for either receiving or sending clock signals. No biggie — just something to be aware of.

HD192. This replaces the 1296 as the hi-res option. It features stereo AES/EBU digital audio I/O and 12 analog inputs and outputs on balanced XLR connectors. I would have preferred Neutrik combo connectors, which can accept XLR or 1/4", but I can certainly understand the decision to go with XLR only. After all, this is a high definition interface, and anyone who’s serious about their audio is likely to avoid 1/4" connectors, and instead work with outboard gear that interfaces with balanced XLR connectors.

Metering is luxurious — 19-segment “ladder” LEDs for all 24 analog jacks measuring –42 to 0 dB, plus two digital over LEDs. Why two? The top one remains lit after clipping until it’s cleared via software. The lower over-LED only lights momentarily when the input/output clips. You can set a “time-out” period, after which the clip hold LED clears; a very professional touch.

Though intended primarily for outstanding A/D/A conversion, the HD192 also has a few digital I/O tricks up its sleeve. A total of 12 input and output channels can be active simultaneously, and there are exactly 12 channels of analog I/O — how do you assign the digital in and out? There’s a “steal” function that lets choose which pair of analog inputs to replace with the AES/EBU input. Clever. It gets better. The digital I/O provides real-time sample rate conversion up to 96 kHz. This means you could integrate, say, a great-sounding outboard digital effects processor that tops out at 48 kHz and still run the session at 96 kHz — the HD192 is perfectly happy to deal with two separate sample rates, thanks to this capability.

PCI-424 Card
The new PCI-424 card has onboard DSP (MOTU calls it CueMix DSP) specifically dedicated to routing live input signals to whatever outputs in real-time with near-zero latency. This is big news. Any audio interface connected to the PCI-424 card benefits from this DSP, so any of the I/O boxes are capable of providing some of the same kind of functionality as a digital mixer. What this means is that live signals can be sent to and monitored from any of the analog or digital outputs with no sample buffer delay and no hit to your computer’s processor.

As powerful as the PCI-424 is, though, it’s not the end-all/be-all to native processor-based music production. There’s been some confusion about what is and isn’t possible with the card’s DSP, so let me clear it up. The 424 card won’t give you the ability to process live input signals through plug-ins with zero latency or increase the plug-in power on mixdown — this is all the domain of your host audio program and computer, which means you’ll still have to deal with sample buffer latency and CPU usage if you want to apply plug-in effects on mixdown or to live tracks played into your computer. However, you can incorporate outboard effects into your monitoring setup with no latency, which is a very cool way of working.

Other PCI card enhancements include an additional AudioWire expansion port for a total of four, which means you can have a whopping 96 possible input and output connections available per card. Not too shabby.

In Use
I put the entire system to good use over the course of several projects. My experience was, for the most part, hassle-free and enjoyable. There were a few hiccups along the way: When I first connected the HD192 to the 424 card, the interface wasn’t available for configuration, even though the documentation says that it should be automatically recognized. Once I reinstalled the 424 drivers and console, everything was a go.

The system never once froze or crashed; it was rock-solid the entire time. That said, there were occasional digital clicks and pops from the 2408mk3 when I’d shut down my Mac. I quickly learned to kill my monitors before powering down, which is good practice anyway.

I was impressed by the build quality of each box, especially the mk3 — it’s tank-tough. Equally impressive was the sound quality across the lot — I could immediately hear an improvement with the 24 I/O and mk3 compared to my older 1224 and 2408. When I checked against the HD192 there was no contest — it smoked everything else. For one session I had the pleasure of tracking acoustic guitar, bass, and vocals though the HD. Sonically, it produced clear, well-defined audio without any coloration or high-frequency harshness.

It did, however, put out more fan noise than all the other units. This will probably be an issue only if you’re working at low levels. We all have separate machine rooms anyway, right? Stick it in there and forget about it!

An interesting fact about MOTU Audio interfaces is that they’re hot swappable. This means you can power off, plug-in, add, and remove interfaces without turning your computer off or restarting. For kicks, I swapped various interfaces at will and guess what? The PCI 424 card never choked. I also played around with jumping from one sample rate to another; the entire system was happy to comply.

Conclusions
I’m not shy to admit I’m a fan of MOTU’s PCI-424 audio system. I have a bunch of digital signals running around my studio, but I’m also concerned with good analog signal paths, and the bottom line is, MOTU has an audio interface that addresses my needs perfectly.

The modularity of it all makes complete sense. About the only option not available is some sort of box with built-in mic preamps. This might be important for some, but I guess that’s why MOTU offers the 828 and 896. I’m not going to complain too loudly, though, because I couldn’t be any happier with these boxes. Chances are you’ll be just as pleased.