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Studio Audio SADiE

Hard Disk Recording System

Article from Music Technology, January 1993

The £5000 add-on for your PC

Mention hard disk recording systems and few people would think of the PC as a likely host computer. But get the software and the interfacing right and things can start to get very interesting...

It may come as some surprise that there are as many, if not more, hard disk recording systems available for the PC as for the Mac; and this is one area in which the Atari ST still cannot really compete. In line with PC prices in general, the cost of such systems is falling and finally coming within the reach of small studios and serious home users. One system which certainly falls within this category is the Studio Audio Disk Editor - or SADiE for short.

Studio Audio are a young company, formed just over a year ago to market and manufacture their digital audio signal processing system. The boards which make up this system have been successfully incorporated into a number of well-known UK OEM-produced audio and video products already, and when the idea for SADiE emerged, all that remained was to write the software.

We are looking at Version 1.5 here, and it's designed to run under Windows version 3.x. I had no problems with either v3.0 or v3.1 - but this is to be expected since it has obviously been written with v3.1 in mind. The program makes heavy use of 3D buttons and sliders to provide an extremely attractive and intuitive user interface - the standard Windows hourglass icon has even been replaced with a steaming cup of coffee!

Main screen showing playlist, level and transport control windows

Installation takes less than 10 minutes, and involves nothing more complicated than inserting both cards into spare expansion slots in the PC, connecting the two cards together with a small ribbon cable, attaching the SCSI disk to the XS card and finally running the cables from the breakout box to the rear panels of the cards. If you do not already have a PC, Studio Audio can supply a complete system with all hardware installed and tested.

On firing up SADiE for the first time, you are presented with three windows. The first is the Level Control window, which acts as a mini mixing desk and provides 4 independently controllable sliders with Mute and Solo buttons and bar graph LED metering. The meters provide a peak-reading facility (where the top LED stays lit for a short period) and can show the absolute maximum signal level of the recorded material. It is also possible to lock together two stereo pairs or all 4 volume sliders in their relative positions, thus allowing you to control overall volume without disturbing the mix. Studio Audio are currently considering adding input faders as well, giving the user the opportunity to mix further inputs with the stereo (or 4 channel) output at mixdown time.

The second window is the ubiquitous Transport Control window which graphically displays all the usual tape transport controls (Play, Stop, Record, Fast Forward, Rewind), along with a digital counter and the ability to set up to 10 location memories. There are three additional time displays besides the 'Current Time' - one is used to set the point to which the editing system returns when the Locate button is pressed, and the other two are used to set left and right locator points used for cycling round a loop and the drop in/out points when recording.

Playlist and trim window - working on cross-fades

All the locate point time displays can be modified by either typing directly into the window or by waiting until the recording reaches the desired point during playback and then pressing the Shift key plus the appropriate Auto-Locate button. This makes for an easy life when reviewing recordings since it is possible to listen through the recording, highlighting particular points using the Shift and Locate To buttons, and then storing these settings in the 10 location memories.

When reviewing these sections later, it is a simple matter to click on any of the memory buttons (causing the Locate To display to be updated with the stored time) and press the Locate button, which moves you straight to the desired location. A nice feature here is that when the Transport window is minimised, the main controls (Play, Stop, Fast Forward and Rewind) appear on the Toolbar at the bottom of the screen.

The third window is the Playlist window which contains the Edit Display List (EDL) and acts as a digital splicing block - more on this in a moment. Any of these windows can be activated and deactivated by pressing the appropriate icon on the Toolbar along the bottom of the screen. One of these icons brings up the Edit window which is where the bulk of your work will be done. After setting up such mundane items as the channels on which you wish to record, the source (analogue or digital), sample rate and resolution, you can record by simply pressing the Record button and adjusting the levels accordingly.

Once recording has finished, the audio data will appear in the Edit window as a graph (or two graphs if you recorded in stereo) of audio levels against time. If you are happy with the recording it can be placed directly into the Playlist and your job is finished. This is real life, however, and the reason you have invested your hard earned cash in a hard disk editor is to do some editing, surely?

Editing is a simple affair using SADiE since everything is driven by the mouse. Let's say, for instance, that you recorded a two-bar introduction which you now wish to extend to eight bars. You simply click and drag the mouse over the area of the recording you wish to edit and that portion of the graph changes colour to indicate you have selected it. You can then listen to that section of recording at the click of a button and the graph scrolls along as the music plays.

Any adjustment which is required to the length of the piece can be made by clicking at the beginning or end of the section and dragging the mouse to a new position. Since we are repeating the same two bars four times here, it would be handy to listen to the section over and over again to check that the loop points are correct. This, once again, is accomplished at the click of a button - the Loop button to be exact. To make our editing more precise, it is possible to zoom in and out on the recorded material allowing each peak or trough to be rendered more accurately on the screen, thus allowing finer and finer adjustment.

Edit windows with two tracks of recorded material and pop-up cross fade window

Preview buttons cause a small section of the selected material to be played either side of, leading up to or just quickly within a track and making the locate points almost redundant.

Along the top of the screen are several menu options including File (from where you can save or load playlists and clip files, and manage your audio disk space); Edit (providing Cut, Copy and Paste operations), and Tools where you can set options such as 2 or 4 channel operation, synchronisation method (SMPTE or MTC), pre and post-roll times and cross fade defaults.

Sound quality was, as you would expect from such a system, excellent. When recording material from CD or DAT the recorded result was indistinguishable from the original - providing care was taken with the recording levels. I completed a small advertising project using SADiE which involved taking sections of a track from a CD, extending an instrumental break in the middle to provide background for a voice-over (previously recorded onto DAT), adding one or two sampled sound effects on the fourth track and recording the finished tracks back to DAT. Because the entire operation had been performed within the digital domain, the finished results were outstanding.

Text-based edit display list with fade window

Everything works well in SADiE, too, and Studio Audio are to be congratulated for bringing such a comprehensive and robust product to market in such a short space of time. And it seems they aren't about to sit back and rest on their laurels either: features planned for the next version (in early 1993) include 24-bit sampling resolution, continuous resync mode for SMPTE and MTC synchronisation, track bouncing and stereo mixdown (allowing panning of each output stream in the master stereo output), equalisation, compression, automated mixing, waveform editing, time-stretch and varispeed. What's more, the upgrade, normally priced at £995, will be available free to all registered V1.5 users.

One can only predict a bright future for SADiE...

More From: Studio Audio & Video Ltd (Contact Details)

Breakout Box

The breakout box, which is a necessity for four channel operation, is also recommended for two channel use. It comes supplied as a standard 1U rack mount unit with 3 cables emerging from the back - one for the X-S card, one for the X-ACT card and a third for MIDI connector on the X-ACT. On the front panel are XLR sockets providing 1 digital in, 2 digital out, 2 analogue in and 4 analogue out connections. There are also connections for SMPTE in/out, video in and MIDI in, out and thru.

The Hardware

The hardware which makes up the system comprises the X-S digital audio processor and the X-ACT analogue converter and timecode interface card. Both of these are standard IBM PC cards for use in ISA or EISA bus machines.

The X-S card is the heart of the system, incorporating the AT&T DSP32C digital signal processor which provides extensive floating point signal processing capacity as well as controlling the on-board SCSI interface. This interface is a key feature of the SADiE system, since it allows direct transfer of audio data to and from a local SCSI drive with transfer rates of up to 2Mb per second without using any of the bandwidth of the PC's main I/O bus. This means that although an 80486 based PC is recommended (mainly because of the requirements of Windows rather than SADiE), a lower powered machine can be used with no loss of audio quality.

Most modern drives have access times in the low teens of milliseconds and this is easily fast enough for random access of two channels of audio. If the four channel system is required, however, more memory is installed on the X-S card to provide larger buffers. The use of a fast hard disk sub-system is crucial to the operation of SADiE since all cross-fades and edits are performed in real time. The drive(s) attached to the X-S card are for audio only, and you will need a separate hard disk and controller in order to run the operating system and SADiE software.

On the rear panel of the card are two phono (RCA) sockets providing SPDIF input and output for simple connection to a DAT machine, and a 25-way D-connector offering differential I/O signals for full specification AES/EBU digital audio - as well as a serial RS422 port.

If analogue I/O, SMPTE or MIDI interfacing is required, this can be satisfied by the addition of a second card to your PC - known as the X-ACT card. This card has stereo analogue I/O as standard, with a 4-channel output version available as an option, as well as a SMPTE reader/generator and a MIDI interface, which enables the unit to lock to MIDI timecode (MTC) instead of SMPTE, if required.

On the rear panel are, once again, two RCA phono sockets and a 25-way D-connector. This time, the phono connectors are used to provide left and right channel stereo outputs whilst the D-connector allows connection to the optional breakout box. A second mounting plate is supplied which attaches to the X-ACT card via a ribbon cable, and whose D-connector presents MIDI signals to the outside world.

Prices: 2 in/4 out Turnkey system - £5995.00 2 in/2 out Turnkey system - £5495.00
Includes: X-S I/O card. X-ACT analogue convertor and timecode interfact card, SADiE breakout box, software, 1 Gbyte SCSI drive, 486/33 colour PC, colour monitor, 100Mbyte DOD drive and 3.5" floppy drive.

2 in/4out D&A Subsystem - £3480.00 2 in/2out D&A Subsystem - £2885.00
Includes: X-S card, X-ACT card and software.

2 in/4out Digital Subsystem - £2685.00 2 in/4out Digital Subsystem - £2290.00 Includes: X-S card and software.

SADiE Breakout Box - £150.00

IBM 1Gbyte drive - £1395.00

IBM 400Mbyte drive - £995.00

Also featuring gear in this article

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Publisher: Music Technology - Music Maker Publications (UK), Future Publishing.

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Music Technology - Jan 1993

Review by Bob Walder

Previous article in this issue:

> Midi By Example

Next article in this issue:

> Stagecoaching

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