Alesis MasterLink ML-9600
MASTER DISK RECORDER

By Michael Cooper

MasterLink is a stereo hard disk recorder and 24-bit/96kHz CD recorder with onboard DSP.

As 16-bit audio continues its slide into obsolescence, the pro audio industry looks for an inexpensive, high-resolution replacement for DAT. Listed at $1,699, the Alesis MasterLink aspires to take the baton from tape-based decks and offer a backwards-compatible, high-bit/high-sampling frequency mastering solution with a robust, disk-based delivery format. MasterLink is essentially a rackmountable, stereo hard disk recorder and 24/96 CD burner with onboard DSP. With MasterLink, you can record to an internal hard drive; apply fades, gain changes, EQ and dynamics processing to your material; and burn down-sampled Red Book CD premasters or proprietary-format 24-bit/96kHz CDs for archival, high-resolution playback or transfer to 24/96 DAWs for simplified file exchange.

Given Alesis' overwhelming success at creating industry standards with its Lightpipe and 16- and 20-bit ADAT formats, the question as to whether MasterLink could become the next prevailing delivery format comes to mind. Let's run MasterLink through its paces to see how it holds up.

Connections

Unfortunately, there are no pre-A/D trims for calibrating the unit with other gear. The balanced I/O clip at +19 dBu and the unbalanced I/O clip at +5 dBV. Most DATs can take +22 dBu. Feeding the MasterLink's balanced analog inputs from my 02R's stereo bus analog outs (0 dBfs out of the console) exceeds the MasterLink's headroom by a hefty 6 dB.

Of course, this is not an issue if you're using external A/D converters with the MasterLink. But aside from headroom, there's no compelling reason to do so, because MasterLink's 24-bit, 128x oversampled converters sound truly excellent.

MasterLink offers two different modes of operation, hard disk and CD, toggled by a front-panel button. Hard disk mode is used to record audio to or play back from MasterLink's 4.3GB internal hard disk, and to create CDs from audio recorded on the hard disk. CD mode is used to play back prerecorded CDs and to copy tracks directly from a CD to the internal hard drive for remastering or compilation purposes. You'll probably be working in hard disk mode most of the time, so let's examine that first.

Recording and Playlist Editing

MasterLink organizes data that is recorded to its hard drive into 16 playlists, each of which can contain as many as 99 tracks. The requisite transport buttons are offered: Play/Pause, Record, Stop, Skip Forward/Backward (to the next/previous track) and Scan Forward/Backward (to audition audio at increased playback speed).

Playlists and tracks can be named. You can change the order of tracks in a playlist, delete individual tracks, and write-protect tracks independently of one another. You also have independent control over the length of each gap between successive tracks. The Version 1.0 software I reviewed did not provide for CD-track offsets, but Version 2.0--which should be out by the time you read this--reportedly will allow start/end offsets up to 30 frames (per 75 CD frames/sec).

MasterLink provides the user with independent control over each track's gain from -18 to +18 dB, adjustable in 0.1dB increments up to Å10 dB and in 1dB increments beyond. You can also assign different start/end fades and signal processing to each track (more on this in a bit).

Tracks can also be cropped to do destructive "head-and-tail" editing of unwanted noise or dead space before or after each track. Five-second previews of original track start/end points are provided. You move the new start/end points by scrubbing with the forward and backward scan buttons.

A large, vacuum fluorescent, 2x16 alphanumeric display indicates all current values for the above parameters, although you'll have to scroll through numerous pages to see all of the DSP-related settings. Cursor Left and Right, Up/Yes, and Down/No buttons are used to navigate around the display and adjust settings. A time display can be set to show either elapsed or remaining time for a single track or entire playlist. Each track's start and end times and length can also be shown. Remaining hard disk space is expressed in hours, minutes or seconds. The display's left/right metering could be a little easier to see, but offers good resolution and defeatable momentary or continuous peak hold modes. A headphone jack and volume control are also provided on the front panel.

Signal Processing

DSP is applied to tracks in six blocks arranged in the following, immutable order: track gain, compressor, parametric EQ, limiter, track fades and normalizer. Individual DSP blocks can be toggled on/off independently. My only complaint is that, for most applications, I would rather have EQ come before compression so that applied boost doesn't undo dynamic range adjustments. That said, MasterLink's dynamics processing and EQ sound downright superb, and the range and incremental control of parameter values will satisfy even the most finicky mastering engineer.

MasterLink's compressor is clean and extremely transparent. Even the hard knee mode is relatively free of amplitude modulation artifacts. Simply put, this is one of the best digital stereo program compressors I've heard.

The compressor offers threshold, ratio, makeup gain, attack, release, key (channel master), knee (choice of hard and four soft knee modes), detect (peak or RMS) and meter parameters. The latter offers six combinations of input/output/gain reduction metering.

Unfortunately, the compressor's makeup gain can only boost and not attenuate, and the downstream EQ block has no output gain control. Whenever EQ boost clips the downstream limiter, you must attenuate levels in the track gain block--necessitating a resetting of the compressor's threshold. It's a minor hassle.

MasterLink's sweet-sounding EQ block offers both parametric and low/high shelving curves. On the downside, there are only three bands and they don't have independent bypasses. But happily, all three bands cover 20.22 to 20.22k Hz in very fine steps, and boost/cut is adjustable in exacting 0.25dB increments. Q is adjustable from 0.1 to 18, making notch filtering and broad tonal shaping a snap.

MasterLink's look-ahead peak limiter is reminiscent of the Waves L1 in that it combines a brick-wall, _:1 limiter with a maximizer function for setting your output "ceiling." MasterLink's limiter sounds outstanding. It's extremely transparent and can really beef up a mix.

Fade-in and -out times can be adjusted for each track in 10ms or 1-second increments. Linear fade, normal logarithmic and inverse log shapes are offered, and they all sound very smooth.

MasterLink also offers a real-time (vs. file-based) normalizer, allowing changes to be made after upstream signal processing settings are altered.

On my wish list for future software updates: a global bypass for all DSP, and multipoint I/O metering before/after each DSP module (to safeguard against potential clipping at various points along the audio path). Notably, the compressor block already provides such metering.

Burn, Baby, Burn

MasterLink can read and write both Red Book (16-bit, 44.1kHz) CDs and proprietary CD24 CDs. CD24 discs can be written to and played back at any of the 12 resolutions that the hard disk can record at, and is not limited to just 24-bit/96kHz data. Only disk-at-once mode is supported.

When you write high-resolution audio to a Red Book CD in MasterLink, the audio is automatically noise-shaped and/or sample-rate converted down to 16-bit, 44.1 kHz on its way to CD. However, the high-res audio files on the hard drive remain unchanged. CD24 discs are played back by MasterLink at their original sample rate and word length.

MasterLink writes Red Book CDs at 4x speed and CD24 discs at 2x speed onto standard CD-R blanks. A 650MB disc will hold a maximum of 19 minutes of 24/96 audio, and the recording process takes about 36 minutes.

File Exchange

MasterLink's CD24 mode records .AIFF sound files in an ISO-9660 CD-ROM disc format along with proprietary information, making the CD24 discs compatible with CD-R and CD-ROM drives. Most computer-based audio editing programs can recognize .AIFF files, raising the possibility of opening a CD24 disc in a DAW to perform further editing. However, Macs cannot recognize the file type and creator info on CD24 discs made with MasterLink's V. 1.0 software. (This is not an issue with PCs.) This should be corrected with the release of V. 2.0 software, and CD24 discs should be fully compatible with Macs. Both Windows and UNIX operating systems are also currently supported.

How about going in the other direction, from DAW to MasterLink? MasterLink can only recognize Red Book audio or CD24 discs; it cannot read .AIFF files created in a DAW. To transfer high-resolution audio or anything other than Red Book audio files from a DAW into MasterLink, you must play the DAW's audio files in real time and record--preferably via digital I/O--to MasterLink's internal hard drive. MasterLink can also copy individual tracks, one at a time, from Red Book CDs to its hard drive. V. 2.0 software will reportedly be able to copy all CD tracks at once.

Conclusions