16-bit Digital Recorder
An American 16-bit digital recording system designed to run with the Apple Mac Plus makes sampling direct-to-hard disk recording a powerful reality. Rick Davies gets his ear to the disk.
INTEGRATED MEDIA SYSTEMS may not be a name that springs to mind each time you think of digital audio - but that may not continue to be the case for long. The IMS Dyaxis is a 16-bit digital recorder that brings direct-to-hard disk recording down into a price range where more musicians can have a look at how this technology can benefit them.
As MT has been pointing out for a while, 16-bit sampling is becoming considerably less costly to implement, and the analogue side of the process is receiving more attention as well. But while many manufacturers are only now bringing 16-bit machines to production, IMS have been busy doing just that for several years. The difference is that IMS have designed custom equipment for clients like LucasFilm and Stanford University, rather than for the mass market.
So, having done the ground work for 16-bit digital audio instruments, all IMS needed to do to adapt their technology to the music industry was to find the right way of packaging it. Rather than commit themselves to any one assortment of front panel controls, IMS designed the Dyaxis as a high-quality digital audio port for the Apple Macintosh, and decided to implement features in software as time and demand allows, rather than trying to get everything into the package first time round.
The Dyaxis itself is housed in a 1U-high rack-mounting chassis which contains the analogue-to-digital and digital-to-analogue conversion hardware. Virtually no controls are provided on this module. The rear panel provides access to the audio world with two balanced lines in and two balanced lines out. Once basic connections are made, the rack is never dealt with directly - short of turning it on, that is.
Unike so many sampling instruments, which store digitised audio in internal memory prior to saving it to disk, the Dyaxis contains no such buffer memory. Instead, the Macintosh co-ordinates the flow of digitised audio from the Dyaxis' conversion circuits to SCSI hard disks.
The fast access time of such hard disks makes it possible for the Dyaxis to pull digitised audio off the hard disk and convert it back into analogue form without having to load it into a buffer first, allowing it to behave as a digital tape recorder, where the maximum recording time corresponds to the amount of hard disk space available. Based on a 48kHz sample rate, rule of thumb is that each 10Mbyte of hard disk holds about one minute of stereo audio. So a 160Mbyte hard disk could hold one album side, for example.
IMS estimate that, in America, when such large hard disks are added to the Dyaxis system, each megabyte of hard disk costs approximately $25. Yet even though several commercially available hard disks work fine with Dyaxis, IMS also plan to provide their own hard disks, which will come formatted, tested, and guaranteed to present no compatibility problems.
Now, it might seem silly to use a hard disk-equipped computer for recording audio when there are digital tape recording systems costing significantly less - such as a Sony F1 with a video recorder - were it not for the graphic editing that a Mac-based system lends itself to. In its first incarnation, the Dyaxis will allow visual editing (looping, enveloping, and so on) of digitised audio, right down to individual bytes - something which is already possible with systems like Digidesign's Sound Designer programs, but which has never been possible with such long sound files.
The Dyaxis also features a "mix" screen from which several stereo files can be opened (like any other file on the Macintosh) and mixed together. Each file an be scaled to the desired level, faded in or out, shifted around in time relative to other files, and panned to one channel or another, making the Dyaxis suitable for all sorts of audio work.
As IMS put it, "the hooks are there" for interfacing with MIDI or SMPTE using other Mac peripherals, though at the time I saw the Dyaxis, it was not yet synchronising to the outside world. IMS did provide a glimpse of how the Dyaxis deals with timecode, however: as you edit a file, a timecode is displayed corresponding to the current cursor position, using the file's starting point as the "zero" reference. From this point on, lining up digitised dialogue or music with external tapes (audio or video) becomes standard procedure. In fact, the Dyaxis features an RS422 connection, so that it can fit into video editing suites and be treated just like a real tape recorder.
Having based the Dyaxis' controls around the Mac, IMS have also opened the system up for third-party software developers, and therefore to many other applications - though there's no news so far of any UK or European distribution, let alone software development.
The Dyaxis has not really been designed as a musical instrument in the way that samplers generally are. What its designers have done is skipped the lightweight applications, and gone straight into the deep end of digital audio, where keyboard samplers generally require a lot of supporting equipment just to keep afloat.
Price $3000. excluding Macintosh and hard disks
Review by Rick Davies
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