Low-end Mac owners used to be left out in the cold in the world of digital audio, but Digidesign's affordable Audiomedia LC board puts that right. Paul Ireson finds out what it can do for him.

The Macintosh LC has been the biggest selling member of the extended Mac family since its introduction, and among those who have taken to the LC in a big way are musicians. Unfortunately, LC owners have been increasingly cut off from the world of digital audio. Though the Mac pioneered affordable digital audio recording and editing for musicians and project studios, largely thanks to Digidesign's innovative software and hardware, only Macs with NuBus slots could accommodate the third-party boards required to provide 16-bit stereo audio capability — and that meant a Mac II or better, not the cheaper LCs and Classics that ushered in the era of affordable Mac computing. More recently, the announcement of Atari's Falcon surely prompted a certain amount of teeth-grinding among Mac users whose pockets aren't deep enough to stretch to Centras, Quadras, and Sound Tools systems.

Fortunately Digidesign have come to the rescue of stranded entry-level Mac users, thereby addressing a gaping hole in the market, with the Audiomedia LC board. The board is essentially a cut-down version of the original Audiomedia, and like Audiomedia it ships with Sound Designer II stereo recording and editing software, this hardware and software combination providing many of the facilities of Digidesign's well-established Sound Tools stereo editing system. It can also be used with software such as Opcode's Studio Vision and Steinberg's Cubase Audio to provide multitrack hard disk recording alongside MIDI sequencing. At over £800, the Audiomedia LC may seem a little expensive when compared to, say, an Atari Falcon, but bear in mind that the Audiomedia LC comes to the market already supported by a wide range of professional software.

THE BASICS

What you get for your money is a small circuit board and Sound Designer II software, plus a rather good manual for the latter — I don't think there are any excuses for not getting to grips with SDII. The board itself looks well-designed and constructed — not out of place inside the LC, in fact. Fitting it to the computer's internal PDS slot (found in all models of the LC) is easy, requiring only a few minutes with a screwdriver (and that only to open the LC case), and the ability to overcome any phobia you might have about fiddling around inside your computer. A small plate on the rear of the LC's case must also be removed, giving access to the two stereo mini-jacks on the board, one for stereo audio input, one for output. There are two adaptor leads that convert the mini-jacks to stereo phono outs — these make a very solid connection with the sockets in the back of the LC, so to all intents and purposes you're dealing with a board with trailing phono sockets.

You will also, of course, need a reasonably sized hard disk, either fitted to your computer internally or hooked up to the SCSI port. Every 10MB of free space gives you one minute of CD-quality stereo digital audio, or two track minutes in a multitrack application. Any drive that you use should have an access time of 28ms or better. My LC only has a 40MB drive, but a 200MB DAC external drive gave me a useful 20 minutes of stereo. Archiving and backup are rather beyond the scope of a brief review such as this — suffice it to say that unless you have a very large hard disk or are working with pretty short files, you'll probably have to work on only one project at a time and wipe that off your drive before you start work on something new. A decent amount of RAM is also required — 6MB is recommended, though I used the board with a full 10MB.

SOUND DESIGNER II

The Sound Designer II software that ships with the LC board provides fully professional stereo recording and editing facilities. The absence of digital inputs and outputs on the board means that, should you want to edit recordings on DAT, you'll have to go through two analogue transfer stages (one on the way in, one on the way out) — hardly ideal, though the quality of such recordings is still quite acceptable. Full SMPTE support means that SDII can be used for sound-to-picture work, and indeed as a stereo digital recorder alongside a MIDI sequencer on another computer. SDII is also a sample editing tool, though support in the version that shipped with the review copy of the board did not extend to several recent and rather important machines such as the Akai S3000 series, nor even the Roland S770/750.

Getting to grips with SDII is a cinch, and the manual is excellent. Every session in SDII starts with either opening an existing Soundfile or creating a new one. The Soundfile window that appears is where you'll do most of your work. At the top is an overview of the whole of the current sound file, and below that a 'close up' view of the waveforms of both left and right channels (or a single channel only, if you're working on a mono file). You can choose whatever scale markings suit you best for both vertical and horizontal views in the Waveform display. For the horizontal scale, you can choose from:

• Minutes and seconds
• SMPTE time
• Sample number
• Flex sample number
• Feet and frames (for film)
• Bars and beats (you define the time interval that represents a bar or fraction of a note)

For the vertical scale, you can choose sample value or percentage of maximum sample value.

The overview always shows the entire Soundfile, and you can chose between a simple timeline (a black line with seconds and minutes marked along it) and a waveform display. The latter is prettier and more informative, but slows down screen re-draws. Particularly if you're using an original LC you'll probably find the timeline preferable for all Soundfiles longer than a few seconds. The close-up waveform view can be zoomed in and out, using either the zooming tool (located above the timeline), with which you 'lasso' an area of the timeline that you want to take a closer look at, or with the Display Scale arrows.

Other tools and icons let you:

• Choose a pencil to redraw sections of a waveform
• Insert markers in the soundfile
• Choose the scrubber to accurately locate with the mouse start and end points of edit selections
• Play the currently selected portion of a Soundfile
• Import a Soundfile from a sampler...

...and so on. Markers are handy for identifying particular sections of audio, and also for locating to during playback.

There are useful keyboard equivalents for many functions — for example, the quickest way to select a portion of a Soundfile for editing is simply to initiate playback with the space bar, hit the down arrow key at the start point you want, and the up arrow key at your end point. If you have the Selector tool chosen (as you normally would), holding the option key down as you click on the waveform display brings up the scrubber, should you need to fine tune your start and end points.

"This is quite definitely the way into digital audio for the average Mac muso..."

Two particularly important icons on the Soundfile window are the Tape Deck and Playlist icons. The Tape Deck button brings up the Tape Deck dialogue box, from where you actually make your recordings. Operation is entirely intuitive, with tape deck style controls (record, play, stop, rewind and so on). You can make either a mono or stereo recording, and you can set gain and monitor your input material. A clip indicator very helpfully lets you know whether input level is too high. Although the Hardware Setup dialogue box only lets you set the Audiomedia LC board to record at the CD sampling frequency of 44.1 kHz, in the Tape Deck dialogue you can choose sampling frequencies between 8kHz and 48kHz.

Non-destructive editing of Soundfiles takes place via Playlists — you define Regions of the current Soundfile, giving them names like Verse 1 and Verse 2, and place them in a Playlist which determines which Regions are played, what order they are played in, and how they are joined together. The actual Soundfile data remains unaltered. When you drag Regions from the Region list down into the Playlist itself, SDII automatically places them end to end (ideal for music editing), or you can simply type in SMPTE start times if this suits your (video) application better. When regions are adjacent you can simply butt-splice them, or use a variety of crossfades (including crossfades with user-defined amplitude curves). The maximum length of crossfades is limited by the amount of free RAM in your Mac, so if you want to use long crossfades, don't run SDII concurrently with any other software.

Don't worry about defining regions too accurately — you can edit their start and end points from within the Playlist to achieve precisely the results you want. You can create for each Soundfile as many Playlists as you want, which means that a single Soundfile of, say, a 4-minute song, could have associated with it Playlists for three different shorter edits, plus two extended versions — and the Soundfile will remain 40MB or so in size. Should you wish to, you can turn a Playlist into a new Soundfile, giving more permanence to that particular version of the original file.

Destructive editing is that which permanently alters the Soundfile, though you can generally undo whatever operation you last performed — provided you have enough free disk space — as SDII will make automatic backups as it goes along.

If there isn't enough space, you will be warned that an operation is irreversible. Without going into tedious detail, you can do everything that you need to be able to do to files — cut, paste, delete and copy portions of Soundfiles, create fades in and out, change overall levels, optimise levels (ie. boost the level of the Soundfile so that the loudest portion sets all 16 bits, thereby ensuring the best signal-to-noise ratio on playback). Sample rate conversion is available.

You can mix up to four mono or stereo files together to a new destination file, and also merge two files (the difference between this and mixing is that a merge crossfades from one Soundfile into another, using markers as start and end points for the crossfade).

DSP FUNCTIONS

The DSP functions are less mundane destructive editing tools, offering several types of EQ, dynamics processing, pitch shift and time compression. A parametric EQ module offers peak/notch filtering, high or low shelving, or high or low pass filtering — extremely versatile, allowing you to set up anything from a gentle low or high-pass filter to a powerful, very narrow, notch filter to remove specific unwanted frequencies. The dynamics module offers compression/limiting, an expander and a noise gate. Both EQ and Dynamics can be applied in real time to a Soundfile, although processing limitations mean that you can only use one module at a time. If you're happy with what you hear, you can apply the DSP to the whole Soundfile (or just a selected portion) and effect a permanent change.

Pitch shift and time compression require the computer to work too hard to be able to operate in real time, so you don't get a chance to preview their effect. Over small shifts, both work pretty well, although simple sounds such as single instruments, rather than full tracks, always emerge from the process rather better. Such processing is time consuming — I found time compression to be around 10 times slower than real time, and EQ and dynamic processing rather faster — of the order of two to three times slower.

The only problems I encountered with SDII concerned copy and paste operations — when copying chunks of audio into the clipboard and pasting them either back into the same Soundfile or into a new one, the pasted data would acquire pops and clicks that had to be edited out with the pencil tool. A call to Digidesign, however, pointed the finger of suspicion at my system folder. Switching from System 7.1 back to System 7.01 cured the problem entirely.

WORKING WITH SMPTE

Sound Designer can both play back and record slaved to SMPTE — or rather to MTC, as the board has no input to accept timecode directly. If you want to take advantage of the facility, you'll need a MIDI interface, from which SDII can read incoming MTC. When playing back in sync to MTC, SDII can operate in one of two modes. In SMPTE Trigger mode it triggers a Soundfile or Region at the appropriate SMPTE time and then uses its internal clock to determine the playback speed of the audio. Provided the file isn't too long (30 seconds or so) and the source of code is reasonably stable, this mode of operation should be fine. For longer files, however, Continuous SMPTE Sync may be better. In this mode SDII continually looks at the correspondence between incoming MTC and the current position in the audio, and if they get out of sync it will alter the playback speed of the digital in order to compensate.

WORKING WITH SAMPLERS

There's relatively little to say about sample editing, as it simply involves the same cut and paste and other tricks that you'd use when performing edits on stereo hard disk recordings. The one difference is that you can also set loop points and transfer these to the sampler. SDII can create an unlimited number of loops, so you'll only be limited by the number of loops that your sampler can manage. Crossfade looping is available for sounds that just can't be looped any other way.

CONCLUSION

What can I say? It works, and it works well. The Audiomedia LC adds to cheaper non-NuBus Macs the all-important ability to record and play back 16-bit stereo digital audio, and it is supported both by Digidesign's own very capable stereo recording and editing software and by all the leading integrated Mac MIDI/digital audio sequencers. This is quite definitely the way into digital audio for the average Mac muso, and though digital i/o would have been welcome, the asking price doesn't seem that much given that this is your entry to the world of professional digital audio.

Further Information

Audiomedia LC £896 inc VAT.

Digidesign UK, (Contact Details).