ML-9600 High-Resolution Master Disk Recorder

by Mitch Gallagher

These days the delivery format of choice for many studios is CD-R. DAT still has a strong hold with some, but I have to admit: other than for loading a few older tracks into my DAW recently for re-mastering, I haven't even turned on my studio's Panasonic SV-3700 in quite some time. In most situations, CD-R, whether created with a stand-alone CD burner or a computer-based CD-R drive, works pretty well. But, in general, stand-alone burners don't offer much in the way of track-editing capabilities, DSP, re-ordering tracks, and so on - you're pretty much stuck with what you send into the machine. A CD-R drive gives you a lot of flexibility, but requires software, a computer, and often computer-based audio I/O to effectively make it work; it's less convenient for burning a quick disc now and then. And what about the need for a way to record and deliver high-resolution stereo masters? The options have been limited: CD-ROMs or a few recorders capable of 24-bit recording have largely been the extent of it.

With the MasterLink ML-9600 high-resolution master disc recorder, Alesis makes a bid to solve the current solutions' limitations on flexibility, power, ease of use, and support for high-res audio. MasterLink integrates a stereo hard-disk recorder with support for resolutions up to 24-bit/96 kHz, DSP-processing and track-editing features, and a CD burner into one convenient, two-rack unit. As a bonus, MasterLink introduces a new format, CD24, which provides a means for delivering high-resolution stereo files on a CD-R disc (see sidebar "The CD24 Format").

Overview

MasterLink packs a great deal of punch into its 2U-rackmountable chassis; it can be thought of as three separate components in one box: A stereo hard-disk recorder, a premastering processor, and a CD recorder. The hard-disk recorder supports resolutions up to 24-bit/96 kHz via either analog (XLR balanced, RCA unbalanced) or AES/EBU digital (IEC958 Type I on XLR or coaxial connectors; see sidebar "IEC958 Type I or S/PDIF?") I/O. The unit can sync to incoming digital clocks present at its input (during playback or record) or to its internal clock.

I would have liked to have seen dedicated word clock I/O for increased flexibility and ease of integration into complex digital rigs. A bigger problem is choosing which of the digital inputs are active whenever "digital" is selected as the input source. The manual states that both sets of I/O ports are active, and that problems can result if digital data is sent to both inputs simultaneously. In my tests, I found that the balanced XLR digital input takes precedence; if you plug in both XLR and RCA coax digital sources at the same time, you'll get the XLR source. To hear the coax source, you have to unplug the XLR cable. One more switch or menu selection would have made this situation much more tenable. As it is, if you're going to be using both sets of digital I/Os, you'll have to reach around behind the box to unplug the one you're not using.

I found the converters in MasterLink to be of good quality - great for most applications. If you're hyper-tweaky about conversion, you can always use your favorite external converters with MasterLink. In many cases, users will probably send signals in from their DAW or sound card digitally; in that case, the converters will be a non-issue.

Once tracks are recorded into MasterLink's internal hard drive (which has space for up to 5.3 hours of stereo 16-bit/44.1 kHz audio), they can be assembled into playlists. There's room for 16 playlists, each of which can contain up to 99 tracks. Once in a playlist, a track can be edited and processed in a number of ways (see below) in preparation for burning to CD.

An audio file can be loaded into as many playlists, or appear in the same playlist, as many times as you like - the playlist is simply a collection of "pointers"; it doesn't contain actual audio data. In fact, if a track appears in more than one playlist, each occurrence can have its own nondestructive editing and processing settings - very cool for A-B'ing different EQ and compression settings or comparing edits before burning to CD.

When you've processed and edited the tracks in the playlist to your liking, simply hit the Create CD button, insert a CD blank, and wait for MasterLink to spit out your finished disc. The playlist and the tracks it contains will be written to a special area of the internal hard drive as a CD image, then the image will be burned to the CD in either Red Book-compatible format or as a CD24 disc.

The process works the same whether you're dealing with 16-bit/44.1 kHz audio or higher-resolution tracks. If you choose to burn Red Book audio discs from high-res files (greater than 16-bit/44.1 kHz), sample-rate conversion and bit-depth reduction (using noise-shaping) will automatically be applied by MasterLink to bring the files down to CD resolution. I found the sample-rate conversion to sound fine; while there's certainly a sonic difference due to reducing the resolution, artifacts resulting from the conversion weren't a problem. Again, if you're tweaky, it's likely that you'll burn the disc in high-res CD24 format and take the resulting files to a mastering house for sample-rate conversion and word-length reduction anyway.

MasterLink also provides a variety of helpful utility functions. You can copy audio tracks from a CD placed in the unit's CD-R drive onto the internal hard drive, sort the audio files on the hard drive in alphabetical order, change metering to no peak hold, momentary hold, or continuous hold, and re-format the hard drive. Other functions are planned, such as the ability to join separately recorded audio files and to split a file into separate pieces. Software upgrades containing these and other enhancements will be installable from the built-in CD-R drive.

Track Editing and DSP Processing

You'll find that MasterLink provides all the track editing and DSP processing power you need for most premastering applications. There are the basics, such as track start and end times, track level adjustment (±18 dB), the ability to name tracks, add tracks, delete tracks, change the track order, and so on, all of which are nondestructive. You can also crop the head or tail of an audio file to remove unwanted silence or noise. This is the only editing or processing function that's destructive and, therefore, can't be undone, but there is a pre-roll/post-roll function that lets you audition the edit before you actually perform the crop. In practice, cropping works well; the start/end preview and scrub functions are cool. You can zoom right in on the place where you want to make your cuts.

MasterLink also gives you the ability to create fade-ins and fade-outs on tracks. The length of fades is adjustable in 10 ms increments, and fades can be as long as 99.99 seconds or the length of the track (whichever is shorter). Three fade-in and three fade-out shapes are provided, including linear and normal and inverse logarithmic. Beyond track-editing functions, MasterLink also has built-in real-time DSP processing capabilities. Included are a compressor, 3-band parametric EQ, limiter, and normalizer. Signals are routed through all four processors in a serial fashion.

The compressor is a straight-ahead single-band affair; you're given control over threshold, ratio, and gain, as well as attack and release times. You can switch threshold detection from peak to RMS, and you can key the compressor off of the left or right channel, or off of the sum of both input channels. The knee setting is adjustable from soft to hard in five increments. Unusual in a device like this is the flexible metering scheme, which lets you see input, output, gain reduction, or "In/Gain" or "Out/Gain." The last two modes allow you to see the sum of the input or output signals on the left channel display, and the amount of gain reduction on the right channel display. The parametric EQ processor offers three overlapping bands (each can sweep from about 20 Hz to 22 kHz). Level can be adjusted ±18 dB per band, and Q can be set from extremely narrow to very wide. As an extra, if you crank a band's Q all the way down, it turns into a high- or low-shelving EQ - a nice touch.

After the EQ, the signal routes through a peak limiter with look-ahead capability. You're given control over threshold, output level (sets a digital "ceiling" level for the signal), and release time; make-up gain is applied automatically based on the threshold setting, making the limiter function as a level maximizer similar to Waves' L1 plug-in.

Last in the chain is a normalizing processor. The Normalizer's function is to scan the track for its loudest peak value and to raise the level of the track such that peak is as loud as possible. One hint: If you change settings in the previous three processors, you should re-scan the track to ensure that the Normalizer is changing the track level an appropriate amount. In use, I found the Normalizer superfluous if you're also using the limiter to maximize levels, but it's handy if all you want is to turn things up as much as possible without causing clipping or affecting dynamics.

All of the editing and DSP processing functions (except track cropping) are real-time and nondestructive. As mentioned earlier, if a track appears in more than one playlist or more than once in a playlist, each occurrence can have its own edit and DSP settings - a great feature. None of the processing becomes permanent until the playlist is rendered into a CD image prior to burning the disc, and, even then, the original file remains untouched. So will the DSP processing in MasterLink replace tens of thousands of dollars in dedicated analog and digital mastering processors? Probably not, but how many project studios (or commercial studios for that matter) have such processors in-house? For quick and easy, good-sounding mastering tweaks, I found the DSP to be wonderful. The fact that it's nondestructive and playlist-specific is excellent. If your needs go beyond this, it's likely that you have other gear you use for mastering anyway or you take your projects to a professional mastering house. But, for many applications, MasterLink's DSP will hit right on the money. I foresee it being particularly useful for doing quick, on-the-fly mastering for reference CDs burnt for clients.

In Use

I recorded stereo tracks into MasterLink using the analog inputs at 24-bit/96 kHz resolution, digitally from Pro Tools|24 Mix at 24-bit resolution, digitally from a DAT at 16-bit/48 kHz, and copied tracks directly from audio CDs to the internal hard drive. A very cool thing is that all these various resolutions can peacefully coexist in the same playlist; they'll all play back at their native resolution until they're actually burned to a Red Book CD. On a CD24 disc, they will remain at their native resolution. But this cool feature also brought up the one area where I ran into some bumps in the road: If you're working in a digital environment, you have to be constantly aware of clocks and sample rates. For example, I had tracks recorded at 44.1, 48, and 96 kHz in the same playlist. But each time a track at the higher resolution started to play, or I even scrolled past it in the list, my digital mixer (which is not 96 kHz compatible) freaked out and lost connection with MasterLink. This isn't a fault of MasterLink, but it does point out that all is not yet completely smooth on the digital-interconnect highway.

MasterLink's user interface is simple and to the point. Front-panel buttons are provided for all the functions; in some cases you'll need to push the button a few times to cycle through the available parameters, but this is easy and fast in practice. A full-featured wireless remote is included with the package; in fact, the remote provides extra buttons for directly editing track start and end points, something not found on the front panel. (This parameter is, of course, also available from the front panel with multiple button pushes.) My only complaint about the user interface is that there are a few functions where it would be nice to have a data-entry wheel, such as when naming tracks and playlists, or when changing parameter values in the DSP processors. As it is, get set for lots of pushing little buttons if you do much DSP or editing.

The entire CD-creation process, whether Red Book or CD24, is simple and straight-ahead. If you're applying much DSP or have tracks that need to be sample-rate or bit-depth converted, rendering the disc image can take some time, but once it's done, the disc image file is on the hard drive and can be used to burn multiple CD-Rs without re-rendering. I burned successful Red Book and CD24 CD-Rs using That's (Taiyo Yuden) and TDK blanks, as well as from the sporty BASF ceramic-backed disc included with the unit; Alesis doesn't specify a particular brand of disc recommended for the unit, but all worked fine. I had no problem playing the Red Book discs in any CD players I checked, and the CD24 discs and files showed right up in my three Macs.

Close the Disc, Write the TOC

Bottom line? Alesis has done a great job with MasterLink. It fills a gap in the current studio gear pantheon that no one else is really addressing. It's well conceived and well implemented. It's going to be great for those who regularly burn demo "reels" for prospective clients. Just keep a selection of music on the hard drive and custom-tailor a playlist aimed at each potential client's needs and taste; you can even add a dash of mastering processing for that last bit of gloss. It should also prove valuable for burning quick reference discs for clients, again with the addition of mastering processing. For serious, preduplication preparation of commercial releases, you may still find yourself at a mastering house - but, even then, MasterLink's CD24 format is useful for backing up and transferring files. Keep those older stereo recorders around for playing archive tapes; for everything else, MasterLink.

MANUFACTURER: Alesis, 1633 26th St., Santa Monica, CA 90404. Tel: 800-525-3747. Web: www.alesis.com.
APPLICATION: Backing up, archiving, and mastering stereo audio to Red Book audio CD or high-resolution CD24 formats.

SUMMARY: An integrated stereo hard-disk and CD recorder with built-in mastering editing and processing, and support for high-resolution audio files.

STRENGTHS: Support for resolutions up to 24-bit/96 kHz. Flexible analog and digital I/O. Powerful built-in DSP processing. Track fade and edit capabilities. CD24 compatibility with computer-based systems. WEAKNESSES: No "double-wide" high-resolution digital I/O. No dedicated word clock I/O. A scroll or data entry wheel would make some operations (such as track naming) faster.

MANUAL: Easy-to-read and informative, the MasterLink manual covers the unit and its capabilities well.
PRICE: $1699 EQ FREE LIT. #: 101