RME Hammerfall DSP

German manufacturer RME attracted a lot of attention a couple of years ago when it released the Project Hammerfall audio interface, a PCI card that combined
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German manufacturer RME attracted a lot of attention a couple of years ago when it released the Project Hammerfall audio interface, a PCI card that combined boatloads of digital I/O with exceptionally low latency. Its follow-up, the Hammerfall DSP system, takes a modular approach to interface design while building on the strengths of the original.

The Hammerfall DSP system comprises two computer cards and two half-rackspace breakout I/O boxes, letting you configure the system as you see fit by combining the appropriate components (see Fig. 1). The PCI card works with any desktop Mac or PC with PCI 2.1 slots. A CardBus interface that provides the same functions as the PCI card is available for laptops. Whether you choose the PCI or the CardBus interface, you extend a FireWire cable to your choice of I/O boxes. (The CardBus cable uses a proprietary pin-out assignment.)

The Digiface I/O box provides two ports (32 channels) of MIDI I/O, three ports (24 channels) of ADAT Lightpipe I/O, one port (2 channels) of AES/EBU-compatible S/PDIF coaxial I/O, word-clock I/O, ADAT 9-pin sync, and a front-panel ¼-inch headphone output. With that much connectivity, I'm hard-pressed to find any fault, but I still wish the headphone output had a dedicated volume knob. The other I/O box, the Multiface, replaces two banks of Lightpipe with eight 24-bit, 96 kHz A/D inputs and D/A outputs on ¼-inch TRS connectors. It also eliminates one MIDI port.

You may be wondering why you give up two ADAT ports to get 8 analog channels. It's because 16 channels at Lightpipe's maximum 24-bit, 48 kHz resolution requires the same bandwidth as 8 channels at 24-bit, 96 kHz resolution. Like a number of current 96 kHz devices, the Hammerfall DSP series provides half as many channels at 96 kHz as it does at 48 kHz. The ADAT ports on the Digiface and Multiface perform “sample splitting” to squeeze four 24-bit, 96 kHz channels through a pipeline originally meant for eight 24bit, 48 kHz channels. (Besides, the Multiface has no room for any more connections!)

TURN THIS DRIVER OUT

RME shows its concern for driver implementation in an unusual way. A portion of the Hammerfall DSP's ASIO driver is actually embedded into an EPROM chip on the card itself. (That's true of the original Hammerfall, as well.) Because the purpose of a driver is to handle communication between software and hardware, this arrangement takes some strain off the CPU and reduces latency. An ASIO system can often achieve latencies as low as 6 to 8 ms. However, RME's resourceful design can reduce latency to 1.5 ms — close to the theoretical minimum.

If you're looking for an audio interface to use with the many Mac and PC ASIO 2.0-compatible applications, the Hammerfall DSP is very attractive. RME has not left Windows MME applications out in the cold, though. The Hammerfall DSP's MME driver can reach the same low latencies with compatible applications running under Windows ME/2000/XP. Note that can is the operative word, and RME disavows any guarantee of extremely low MME latencies. RME plans to develop WDM streaming drivers in the future, though no target date has been announced as of this writing. Those drivers are intended to make low-latency operation much more achievable under Windows ME/2000/XP.

Low-latency GSIF drivers for use with Tascam's GigaStudio are included, as well. In addition, Linux drivers are under development for the Hammerfall DSP system and may be available later this year.

GET IT STARTED

I installed the Hammerfall DSP CardBus interface in a 1 GHz Celeron notebook with 256 MB of RAM and running Windows XP. I installed the Hammerfall DSP PCI interface in a Pentium III/450 MHz desktop computer with 128 MB of RAM and running Windows 98SE. I swapped a Digiface between the two systems, using RME's ADI-8 Pro A/D/A converter as a front end. I begged and pleaded for a Multiface, but at review time, there was a significant waiting list. (RME expects that to be resolved by the time you read this.)

Installation was a breeze on the notebook computer and a minor annoyance on the desktop. However, the Hammerfall DSP's U.S. distributor, X-Vision Audio, patiently and accurately guided me to a resolution. Score one for customer support.

Once I had the hardware properly installed, Steinberg Cubase VST/32 5.0 and Emagic Logic Audio Platinum 4.8 recognized it and let me configure it in the normal ways (see Fig. 2). Cakewalk Sonar 1.3, however, was a bit more of a challenge, because at first it didn't recognize the card. An e-mail to technical support quickly brought a suggestion to tell Sonar to always use MME drivers, which immediately solved the problem.

Another occasional annoyance was that Sonar kept telling me that the Hammerfall DSP was “not compatible with current settings or in use by another device” when I started the program or made changes to the audio setup. That response proved to be erroneous, because all I had to do was pat the computer reassuringly and click on Use Anyway, and all was well. One of the few ways in which RME's support disappointed me was that its configuration tips for Cakewalk were for Pro Audio 7 — three versions back.

With a desktop computer, the Digiface is powered through the FireWire cable, but when used with a notebook, it requires external power. A CardBus connection simply doesn't provide enough voltage, so that interface ships with three power supplies. First is the traditional lump in the line, which is always preferable to the dreaded wall wart. Kudos to RME for making the transformer light and small, giving it a power-present LED, and putting it in the middle of a 12-foot cord.

Showing real attention to the needs of mobile musicians, RME also includes a 12 VDC adapter, which plugs into an automobile cigarette lighter, and another cable to be used with — believe it or not — a rechargeable battery. Each cable is a healthy 10 feet long. Go to RME's Web site and check out the article “HDSP System: Notebook Basics — The Audio Notebook in Practice” to see some thoughtful design at work.

HAMMER TIME

So how does it sound? The Hammerfall DSP's all-digital I/O doesn't “sound” like anything. Okay, the headphone output sounded perfectly fine, clear, and quiet. Although it wasn't officially part of the review, I was pleased with the sound of the ADI-8. Its front-panel controls couldn't be easier to use, and I like the fact that it has a schematic on the top panel. (For more on the ADI-8, see the sidebar “Getting Converted.”) I can't vouch for the Multiface, but if it lives up to its published specs, it should be a worthy contender.

The question, then, is how about that latency? The long and short of it is that the Hammerfall DSP can indeed achieve negligible latency on a properly configured machine under the right circumstances. During my testing, I was sometimes able to operate at the system's lowest buffer size, and though I didn't do any bench testing to confirm the 1.5 ms claim, it was as close to real time as it needs to be.

Maintaining those ideal circumstances, however, proved to be difficult. Even though I run a pretty lean configuration, the audio performance at the lowest latencies was not consistently clean. Occasionally, the sound broke up — sometimes in subtle ways and other times in gross ways. Bumping up the buffer size made the crackles and distortion go away but at the price of slower response.

Here are some things to keep in mind if you're going for those single-digit latencies. Using the ASIO drivers under Cubase and Logic Audio yielded somewhat better results than using the MME drivers under Sonar. Nevertheless, it's surprising that RME is able to get MME latencies in the same ballpark as ASIO. That's the job the newer WDM drivers are supposed to do.

Another thing to keep in mind is that plug-ins eat up buffers. If you want to monitor with reverb and EQ, you may have to settle for higher latency. On my machines, 1.5 ms was pretty much out of the question if any effects were running, but 3 ms was sustainable with a reverb. Of course, monitoring with plug-ins is the whole point of low-latency audio interfaces. If you're not going to sweeten the cue mix with some reverb, why not just use the direct hardware monitoring available on most interfaces?

Likewise, the more tracks I recorded, the higher I needed to set the buffer. Exactly how many tracks and how high the latency was varied from program to program and from desktop to laptop. Suffice it to say that even though I'm impressed with the Hammerfall DSP's performance, I'm unlikely to subject a client to the latency-versus-audio-quality trade-off any time soon. For the foreseeable future, I'll run at larger buffer sizes and rely on monitoring through a console or through direct hardware monitoring.

Direct monitoring with the Hammerfall DSP is made a lot nicer by the inclusion of an applet called TotalMix (see Fig. 3). It's a 1,456-channel (that's right, 1,456) software mixer that provides almost limitless flexibility in moving signals between hardware inputs, software outputs, and hardware outputs. You can create multiple headphone mixes, pass a live stereo reference mix to your DAT while you're multitracking, and do a whole lot more.

CAN'T TOUCH THIS

Once the hardware was successfully installed, I had almost no problems with the Hammerfall DSP system, though my notebook didn't like seeing the CardBus card without the Digiface attached. It let me know by freezing and crashing for no apparent reason. Because CardBus cards are hot-swappable, I've developed the habit of stopping the device and removing it if I need the Digiface for my desktop.

RME deserves credit for its attention to detail. For example, the FireWire cables packed with the PCI and CardBus cards are 14 feet long. When was the last time you were able to sit back and ask, “Where is the most convenient place to put my breakout box?” Cables as long as 33 feet are available, and with three of those cables and two repeater boxes, you can place the Digiface or Multiface as much as 100 feet from your computer.

The Hammerfall DSP's driver CD is date stamped and filled with drivers and manuals (in English and German) for RME's entire line of products in all supported versions of Windows. It also holds a complete version of the company's Web site, including tips and tech info. That's particularly noteworthy, because it includes some great articles such as “Tuning Tips for Low Latency Operation” and five articles about using notebooks with the Hammerfall DSP system.

The Hammerfall DSP system, though not dirt cheap, offers an economical approach because of its modular design. Someone who operates desktop and laptop systems, can buy a PCI card and a CardBus card and share a Multiface or Digiface between them. Someone who owns a digital mixer can buy a pile of digital I/O without wasting money on redundant analog I/O. For the truly power hungry, multiple Hammerfall DSP cards can be installed in the same machine. (If you're on a tight budget, you can still buy the original Project Hammerfall system; see the sidebar “Vintage Hammer.”)

Even though the much ballyhooed 1.5 ms latency proved impractical on my machines, I'd be happy to own a Hammerfall DSP system. Its modularity appeals to me, as does its efficient design and quality construction. Its combination of high resolution, numerous inputs and outputs, and expandability give it staying power in these gadget-of-the-month times.

PRODUCT SUMMARY

RME
Hammerfall DSP
digital-audio interface
PCI interface card $315
CardBus interface card $355
Digiface digital I/O box $650
Multiface A/D I/O box $860

FEATURES5.0EASE OF USE4.5AUDIO QUALITY4.5VALUE4.5

RATING PRODUCTS FROM 1 TO 5

PROS: Flexible modular design. Support for high-resolution audio. Low-latency operation. Word-clock I/O. ADAT sync. Can cascade multiple units. Powerful software mixer applet. Good notebook support.

CONS: Lowest latencies are highly host-dependent. No front-panel headphone volume knob.

Manufacturer

RME Intelligent Audio Solutions/X-Vision AudioUS (distributor)
tel. (330) 747-3857
e-mail info@xvisionaudio.com
Web www.rme-audio.com

GETTING CONVERTED

Adrift in a veritable sea of digital inputs and outputs, I needed a good set of converters to connect my analog world. RME was kind enough to send me its ADI-8 Pro ($1,750), which is an 8channel, 24-bit, 48 kHz analog/digital interface. The ADI-8 Pro features eight analog inputs and outputs on balanced ¼-inch TRS connectors, two ADAT Optical I/O ports, two TDIF-1 ports, and word-clock I/O. The analog inputs are also available through 25-pin D-sub connectors.

A lot of thought went into the design of the ADI-8 Pro. The analog, ADAT, and TDIF-1 outputs are all active simultaneously, and in normal operating mode, the secondary ADAT and TDIF-1 outputs mirror the primaries, which lets you use the ADI-8 Pro to feed as many as four digital devices at the same time.

The real purpose of the extra digital ports, however, is to support bit splitting, a way of remapping each channel's 24 bits across the space available on two channels of a 16-bit device. On playback the ADI-8 Pro recombines the split signal into a single 24-bit output. Four input channels split that way would use all eight channels of a single ADAT/TDIF port, so the extra ports are needed to transfer channels 5 through 8 to a second bank of eight 16-bit channels.

All of the unit's functions are selectable using front-panel switches that have clearly labeled status LEDs. Two-stage input and output level meters are situated on the front panel, as well. Input and output levels are independently selectable between -10 dBV and +4 dBu.

The ADI-8 Pro is easy to use and sounds great. Its feature set might be overkill for some users, but for others its flexible digital I/O is just what the doctor ordered.

VINTAGE HAMMER

The original Project Hammerfall, aka the Digi 9652, is a great way to get most of the positive attributes of the Hammerfall DSP system for a few bucks less. For $665 you get a PCI card with all of the Digiface's audio I/O built in. The only connections you give up are the MIDI ports. To make room for all of the connectors, you need a second space on the back of your computer but not a second PCI slot. The second space houses the third ADAT port and the word-clock I/O. If you don't need those, you can save $90 by buying the Hammerfall Light, which is the PCI card without the extra connections.

What do you lose by pinching pennies? Aside from the DSP system's modular design and the convenience of placing your audio connections 14 feet from your CPU, you miss out on the TotalMix application, the aforementioned MIDI ports, and what RME calls dynamic bus utilization. That's designed to improve PCI efficiency in the Hammerfall DSP, and on my desktop, the original Hammerfall was slightly less happy with the lowest latency settings than the Hammerfall DSP was. It was not a huge difference, though — far from a disqualifier for the original Hammerfall.

Having worked out my installation bugaboos on the Hammerfall DSP, I was able to install the Project Hammerfall card in a snap. Its configuration utility is almost identical to its sibling's, and configuration within Cubase VST and Sonar is just as simple. For anyone with lots of Lightpipe gear to connect, the Project Hammerfall and the Hammerfall Light are well worth a look.

Hammerfall DSP Specifications

Audio I/O (Digiface)(3) ADAT Optical (Lightpipe); (1) S/PDIF coaxial (AES/EBU compatible); (1) ¼" headphone outputAudio I/O (Multiface)(8) ¼" TRS analog; (1) ADAT Optical (Lightpipe); (1) S/PDIF coaxial (AES/EBU-compatible); (1) ¼" headphone outputSynchronization (Multiface/Digiface)(1) word-clock I/O (BNC); (1) ADAT 9-pin syncMIDI Ports (Digiface)(1) In/Out front panel; (1) In/Out back panelMIDI Ports (Multiface)(1) In/Out front panelAudio Channels(26) In, (26) Out @ 48 kHz; (12) In, (12) Out @ 96 kHzResolution16-, 20-, 24-bit; 32, 44.1, 48, 88.2, 96 kHz sampling rateDriver SupportASIO 2.0 (Mac/Win); GSIF (Win 98/ME)