I bought my first RME product, an ADI-648 MADI-ADAT converter [Tape Op #63] a decade ago, when my primary recording devices were an Otari MTR-90 2'' tape machine, a TASCAM MX-2424 standalone HD recorder [#22], and Pro Tools|HD running on a single-processor Mac G4. Ten years later, my PT|HD rig is long sold, the MX-2424 is used for resurrecting archives, and the only time I turn on my MTR-90 is when visitors to my studio ask to see all the meters dance. The ADI-648, on the other hand, is still a crucial component of my studio after all of these years; that kind of longevity is rare for anything digital! A few months after I sold my PT|HD rig, I purchased an RME HDSPe MADI interface [#63], first installing it inside a quad-core Mac Pro then later in a custom-built,near-silentPCfromCoolTechPC[#67].Forfive years, the 64-channel HDSPe MADI was my primary interface, tying together my computer, my Sony DMX-R100 digital console [#25], and the aforementioned ADI-648, with a set of Apogee AD/DA-16X converters [#59]. Although the core of my studio is digital, I still do a lot of analog processing. With my collection of compressors, EQs, and other analog processors growing, I wanted more channels of I/O for my DAW to support lots of pre-fader analog inserts while mixing on my DMX-R100. When I heard that RME would be releasing the updated HDSPe MADI FX interface with three times the I/O as its predecessor, I put myself on the preorder list and waved my money. Christmas came in June when I received one of the first units off the assembly line.

The HDSPe MADI FX is a PCIe card and an expansion board that together provide 192 channels of I/O via three sets of MADI connectors (two optical and one BNC), plus two channels of I/O via AES, as well as two channels of analog output via a TRS headphone jack. All of these channels can be used simultaneously. MIDI and Word Clock I/O are also included. (An optional expansion board with optical connectors can be swapped for the included expansion board if you want to go all optical on the MADI.) Why would any sane person need so much connectivity? Well for starters, mobile and location recording often involve a hundred or more channels for stage mics, line-level instruments, backing tracks, audience mics, etc. The HDSPe MADI FX is a no-brainer in that capacity, especially because it has a special redundancy mode for seamless failover from one MADI input to another in case one or more of the feeds goes south. Orchestral recording is another discipline that can easily take advantage of all the I/O in a compact form factor; same with mixing for film. But what about a project studio like mine? 

My HDSPe MADI FX is connected to my DMX-R100 through the first set of MADI connectors; this gives me 48 channels of I/O between the console and my DAW, the maximum number supported by the DMX-R100. The second set of MADI connectors goes to my ADI-648, which in turn handles digital I/O for my Apogee converters and my MX-2424 recorder. The third set of MADI? Well, they're unused for now, but I won't be surprised if I find a need for them in the near future. For now, I have countless ways of routing audio between my DAW, my console, and my various outboard devices - and with the included TotalMix FX application, I never have to leave my chair to change the routing.

Actually, the term routing doesn't begin to cover the capabilities of TotalMix FX, the most comprehensive audio interface software I have ever seen. TotalMix FX is a matrix mixer on steroids. First of all, every output has its own, fully-featured 390-channel mixer represented in the application. No, that's not a typo - each of the HDSPe MADI FX's 196 output channels (98 stereo) can have its own independent mix of 194 input channels and 196 playback channels (97+98 stereo). Moreover, every one of the input and output channels in TotalMix FX has a 3-band parametric EQ and a Dynamics processor that can do simultaneous expansion and compression. Additionally, every input and playback channel has an FX Send and every output channel has an FX Return control for the built-in Reverb/Echo processor. A straightforward Control Room section provides main output assignment, A/B speaker switching, dim, talkback, and so forth. You can read more about these features in my recent review of the RME Fireface UCX [Tape Op #88], but to summarize, TotalMix FX's EQ and Dynamics are very usable but aren't "character" pieces, and the Reverb can be tweaked to add believable ambience to a headphone mix. Oh, and I almost forgot to mention that each pair of channels has a Mid/Side matrix available to it, and Loopback allows you to send submixes back to the host application. I'm sure you can imagine how daunting TotalMix FX must look onscreen. Yes it seems complicated at first, but after a few hours of use, the interface is a breeze to navigate, and thankfully, you can hide any channels you don't need to see. You can also place it in Matrix View, which is a straightforward table made up of highlighted rectangles that show which inputs and playback channels are routed to which outputs (and numerically at what signal level). I haven't tried controlling TotalMix FX from a MIDI controller, but it does answer to the ubiquitous Mackie Control protocol as well as to OSC.

The HDSPe MADI FX, like other RME interfaces, also supports ASIO Direct Monitoring. That means Windows applications like Cubase, Nuendo, Sequoia, and Samplitude can directly control the near-zero-latency monitoring capability of the interface - a huge convenience that can't be understated. Therefore, when I'm running Cubase [Tape Op #90], I rarely open TotalMix FX other than for checking its comprehensive metering, or for routing audio between devices in my studio independent of what I'm doing in Cubase. For example, I can insert an analog processor on one of my DMX-R100's channels via my Apogee converters, or I can even use TotalMix FX to patch together multiple applications running on my computer.

Unfortunately, Pro Tools does not support ASIO Direct Monitoring, so for near-zero- latency monitoring, your options are building monitor mixes in TotalMix FX or using an external mixer. But then again, if your hardware is fast enough, you could forgo creating a special near-zero-latency mix. On my aforementioned 4 year old PC, for example, I was able to record at 44.1 kHz to Pro Tools 10 [Tape Op #89] with the HDSPe MADI FX's buffer size set to its minimum of 32 words while playing back 24 tracks of previously recorded audio. With the monitor mix built within PT, I measured a roundtrip latency (MADI input to MADI output) of 2.6 ms. Even though my Apogee converters add an additional 1.6 ms of delay for a total roundtrip (analog to PT to analog) of 4.2 ms, that's still less than the time it takes for sound to travel through the air from a guitar amp on the floor to the guitarist's ear. With the buffer size set to 64 words, roundtrip latency (MADI to MADI) measured 4.8 ms. In contrast, using ASIO Direct Monitoring or monitoring through TotalMix FX, roundtrip latency drops to less than 0.07 ms at 44.1 kHz regardless of buffer size.

Other features worth a shout-out are DIGICheck metering software (EBU R128 compliant), SteadyClock jitter suppression, and compatibility with both Mac OS X and Windows. Also, as you would expect, channel counts are halved at 88.2 and 96 kHz, and halved again at 192 kHz. Going through all the wiz-bang capabilities of this interface would take more space than what's allotted for this review, so download the well- written, 84-page manual if you're interested in learning more. Suffice it to say, RME manufacturers top-tier gear, and I couldn't be happier with the HDSPe MADI FX that is now the main point of connectivity in my studio. And like my other RME products have, I'm certain it will serve me well without any problems for many years to come. ($2000 street; www.rme-audio.com) -AH 

Tape Op is a bi-monthly magazine devoted to the art of record making.

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