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PC Hard Disk Recording SystemArticle from Sound On Sound, June 1993 |
It's British designed and built, but is it the best?
Brian Heywood looks at this easy to use PC-based pro digital audio disk editor from Studio Audio & Video.
You'd have had to be locked away in a salt mine in Siberia this past year not to have heard something about the revolution in digital recording. While digital recording has been with us for quite a while now, 1992 saw the first systems that fell into the price range of musicians and small studios. The SADiE system from UK-based Studio Audio & Video Ltd is one such system that is designed to give you a professional digital audio disk editor without breaking the bank.
The subject of digital recording is one that tends to arouse the passions of both musicians and producers, and stock phrases like 'analogue tape compression', 'ear fatigue' and the like will be bandied about.
Whilst there is much to be said on both sides of the argument, digital recording is still gaining market share at an astounding rate — for instance, Alesis recently announced that they had shipped 10,000 ADATs worldwide. The absence of noise and the subsequent large dynamic range that can be achieved using digital technology is really too attractive to ignore. So, as a result, everyone seems to be going digital — but what sort?
There are two ways to get into multitrack digital recording: one is digital tape (à la the Alesis ADAT/Tascam DA88) and the other is hard disk recording. Tape-based systems are very much like the traditional analogue tape recorder; you effectively record your eight tracks of sound along the length of the tape. The amount of time that can be stored on the tape depends on its length, the tracks are still there whether you record on them or not. There is usually no way of editing the sounds once you've recorded them apart from 'dropping in' or overdubbing a new section of the track. One slight advantage of an analogue machine is that you can edit the tape with a razor blade — not possible with a digital tape.
Hard disk recorders, on the other hand, tend to offer very good editing facilities, allowing you to 'cut and paste' sections of audio in the same way that you can manipulate MIDI data in your sequencer or text in your word processor. They can also make efficient use of their hard disk storage, since they only allocate storage for sound that has been recorded — silent sections of tracks don't take up any disk space. Hard disk recorders also tend to have 'tools' that let you process the tracks after they've been recorded, allowing you to perform such operations as time stretch, pitch change, digital equalisation and mixdown.
Each approach has its advantages: tape gives you more minutes of recording time than the equivalently priced disk-based system, whilst disk gives you the ability to edit the tracks.
You can even build a hybrid system using an Alesis ADAT or Tascam DA88 and Digidesign's new Session 8, say, to give the advantages of both. I am of the opinion that the tape-based systems are really just a halfway house, and will become much less important as the price of large hard disks comes down. When considering a hard disk recorder, it is very attractive to get one that is based on a standard personal computer. The reasons are: you get a familiar user interface, you can take advantage of the computer manufacturer's economy of scale to reduce costs and thus get a cheaper system, as long as you already own the computer! Probably the best known purveyor of this type of system is Digidesign with their Apple Macintosh-based products, but there are a number of PC-based systems as well.
The IBM PC family of computers would seem to be an ideal platform for hosting a hard disk recorder, since it has been designed from the 'ground up' to take expansion cards. The popularity of the PC also ensures that component costs are low, so items such as mass storage and memory are fairly cheap. There have been a number of hard disk recording systems available on the PC for some time, ranging from the Spectral Synthesis Audio Engine (prices starting at around £10,000) down to the Digital Audio Labs CardD budget system (around £1,000).
Recently there have been a number of mid-range systems released for the PC from the likes of Digidesign (Session 8) and the Cheetah spin-off company Soundscape Digital Technology (Soundscape). The SADiE system being reviewed here has been around since the middle of last year and falls into the midrange category, with prices starting from around £2,700 (inc VAT) for the most basic digital system. This doesn't include the hard disk, which needs to be a fast SCSI disk, so you're probably looking at a starting price of around £3,500. As well as selling the cards, Studio Audio will supply a complete working system with a 33MHz 486 PC, 4Mb of RAM, a VGA monitor and a 1 Gigabyte SCSI disk starting at around £6,500. This compares favourably with the prices of the Digidesign Session 8.
The SADiE system is based around either one or two expansion cards and a large SCSI hard disk installed in a PC running Windows. Like most systems in this price range SADiE uses it's own 'local' hard disk to store the audio information, thus avoiding the DOS disk access 'bottleneck'. Studio Audio recommend at least a 486SX with 4Mb of RAM, although I had the system running quite happily on a 40MHz 386 PC with both 4Mb and 8Mb of RAM. It's a bit of a mystery to me why the PC's processor needs to be so powerful, since all the audio work is being handled by the expansion cards — maybe it's just to get the fastest possible screen update, in which case a graphic accelerator card might be a cheaper option.
The basic 'single card' configuration has two digital inputs and four digital outputs (SPDIF or AES/EBU), so you will need to use your DAT machine's digital I/O or buy external convertors.
Adding a second card gives you two analogue inputs and four analogue outputs, as well as SMPTE/EBU and MIDI time-code inputs and outputs. If you're working in video post-production you can generate longitudinal timecode sync'd to a video signal. There is also a rack-mounted breakout panel that brings all these signals out to standard audio connectors. The editing software is the same for both configurations, so it's a simple matter to upgrade the system by adding the second card.
The SADiE editing software gives you a 4-track system, which is angled towards audio post-production rather than recording applications. In SADiE terms, each track can have two sound clips playing at any one time so that it can perform crossfades in real time. This means that you can have up to eight tracks available at any one time, although you are still limited to four outputs. This real-time aspect of SADiE is probably the most interesting feature of the system, as it means that there are no pauses while the edits are written out to disk, also conserving that precious disk space.
The core of the system is the X-S card, which contains the AT&T floating point Digital Signal Processor (DSP) and the SCSI hard disk interface. This card handles all the audio processing and reads and writes the audio data to the SADiE SCSI disk. It is a densely packed, full length card with a 25-way D-type connector that carries all the input and output signals and two RCA 'phono' connectors that can be connected up to your DAT's SPDIF sockets. The SCSI disk is connected using a 50-way ribbon cable that allows you to connect to an internal drive, but could give you problems if you want to connect to an external device.
The second card is called the X-ACT and adds the analogue inputs and outputs, MIDI and timecode support. This is another full length card with a metal shield over the analogue electronics.
The two cards can fit into adjacent slots in your PC, though Studio Audio recommend that you leave a gap between the two cards to improve ventilation (for cooling). This gap can be conveniently filled by the MIDI connector, which comes out on a 'flying' lead to a dummy back plate. The X-ACT card is connected directly to the X-S via a ribbon cable and thus only takes power off the PC bus. The card uses 64x oversampling delta sigma convertors which are capable of 24-bit sampling, although this is not implemented in the software yet. The card also has an onboard processor to handle timecode, as well as a video sync separator.
The cards proved simple to install, with none of the hassles that tend to be associated with sound cards — there are no IRQ numbers or DMA channels to worry about. In fact there is only one setting mentioned in the manual, which is on the base address of the X-S card. Luckily there were no clashes, so all that needed to be done was to interconnect the two cards using the supplied ribbon cable and connect up the 1Gb hard disk. One niggle with the cards was that once the lid is back on the computer, it is difficult to tell the two cards apart; though it would be simple enough to label the back plates.
The software is installed using a standard Windows setup routine, which copies the software on to the PC's hard disk and then creates a program group with the SADiE icon, a SCSI disk formatting utility, and a 'notepad' file of release notes. Another niggle here is that the formatter is very unfriendly and there is no obvious way of quitting it if you start it up by mistake.
Regardless of the quality of the hardware, this kind of system will stand or fall by the calibre of the software. It must be powerful without being overly complicated; it must provide the basic tools required to do the job; it must be reliable; and above all it must be quick to use. The SADiE software hits all of these targets to a large extent, its only (present) failing being in the lack of some advanced sound manipulation tools.
"...SADiE is the bee's knees when it conies to audio post-production. I used the system both to master records and to compile a commercial 'talking book', and not only did I get the work done quickly but I had fun doing it."
There are a number of screen windows that control the operation of SADiE and allow you to edit the digital audio files. The familiar tape transport buttons are there to control the basic playback functions as well as provide 10 locators, a timecode display and varispeed. The overall level of each track is controlled from a small mixer panel, which also has a useful peak level readout. There is a graphic editor for creating and altering individual sound clips and two windows for compiling the clips into finished tracks. Each of the windows can be activated or hidden using a button bar along the bottom of the main window. One nice touch is that the basic transport controls appear on the button bar when the main transport control panel is 'turned off'..
An interesting aspect of the system is the way in which it treats the digital audio data. When the sound is recorded it is placed into a single file — or a 'track' in SADiE terms — which is stored on the SCSI disk. The contents of this file are never altered; instead, any edits that you subsequently perform are stored as a set of instructions — or a 'clip' in SADiE terms — which SADiE will perform during playback. This means that the edits are very fast — since no data is being copied — and that the edits take up very little additional disk space, so you are unlikely to run out of disk space halfway through a complicated editing session.
The Edit window shows you a graphic representation of the audio clip you are working on and allows you to quickly set up the start and end point of the clip, as well as the fade characteristics and overall level. There are about 20 different fade curves to choose from and the fade durations are defined in timecode terms (ie. hours, minutes, seconds and frames). The clip level control allows you to balance the relative levels of the clips, which is useful if you're using samples from different sources.
It is important to realise here that you are not seeing the actual waveform but a simplified version or 'profile' of the sound data. The use of profiles means that you don't have to wait ages for the screen to update as the sound data is read off the hard disk. The lack of detail didn't particularly bother me, as there is enough information to see the general 'shape' of the sound, and the scrub edit feature lets you use your ears to fine tune the edit points.
Once you have amassed some completed sound clips, you can start putting them together. This collection of clips is called an EDL (a term derived from the broadcast industry, which stands for 'Edit Decision List'), which is just a complicated way of describing a cue list. There are two types of EDL in SADiE; the 'Tracklist' and the 'Text EDL'.
The Text EDL page is simply a list of clips along with their start times, duration and track details, and has probably only been included for the video post-production market. The Tracklist is a graphical representation of the same information which provides a much more intuitive way of working with the clips. Whichever type of EDL you decide to use, SADiE allows you to have two 'on the go' at one time, letting you try out ideas using the second EDL.
The Tracklist window shows the clips as horizontal bars with the fades shown at either end, rather like tape splices. The clips are colour-coded for clarity with adjacent clips alternating between blue and green, and overlaps can be outlined if required. The clips can be picked up and moved with the mouse, giving a very 'hands on' feel to creating the EDL, and the Trim window is extremely useful for setting up crossfades between two clips graphically. The Tracklist is probably the most useful window in the package, since this is where you see the current work as a whole. The only thing I missed was the ability to quickly fire up the Edit window for a particular clip in the Tracklist; instead you must select the clip from the list of clips in the clipstore, which can be quite large for a complicated EDL.
Recording the tracks is easy enough: simply use the Setup menu to enable recording, name the track and click on the record button in the transport window. The track levels are controlled with the faders on the mixer window, which can be ganged together for stereo material. There is also a Peak Program Meter (PPM) display and a rather useful Margin display that will tell you if you run out of headroom. The recorded track is placed directly into the clipstore, making it available for editing or inclusion in a Tracklist EDL. You must be careful to enter a new name each time you record a new source, otherwise you will lose the previous track; a more helpful warning message would be in order here. Unfortunately, you can't monitor an existing clip or EDL while you are recording a new one, so you can't use SADiE as a 4-track 'portastudio'.
PULLING IT APART
Once you've recorded the track, you might want to quickly slice it into sections before editing the clips in detail. Well, SADiE's designers have thought of this as well; they've provided a razor blade button that will automatically create a clip as you play back the original. You can even glue clips back together (as in Cubase) if you make a mistake. One additional feature I would like to see implemented would be to automatically split up a load of clips that were separated by 'digital silence'. This would allow you to dump across a set of samples or loops, using your sampler's digital interface, without having to first split them up by hand using SADiE's Edit window.
There are some problems with SADiE, the most obvious being the lack of a decent manual, although the inclusion of on-line help is a definite plus point. In terms of features, SADiE lacks some of the common DSP functions found in equivalent computer-based systems. The lack of features such as time stretch, pitch change and track bouncing mean that certain common post-production and 'break beat' tasks are not possible.
According to Studio Audio & Video Ltd, all the above features are going to be added to SADiE before the end of this year. In addition, they are planning to add equalisation, stereo mixdown, audio compression, click removal and various other goodies. In fact, anyone who buys a SADiE system will receive free software updates for the next 12 months. Some of the more interesting future developments include the generation of PQ codes for CD mastering and recordable CD support.
It's very easy to fall into the trap of chasing the latest technology simply because it's trendy or because it has a pretty face. Thus you might consider carefully about going over to digital tape since — although it does give definite quality improvements — it doesn't really give a major improvement in your working environment or productivity. However, this argument doesn't really apply to hard disk recording systems since the extra features for constructing masters (or talking books or whatever) leave the traditional methods of tape editing dead in the water. Basically, if you do a lot of tape editing, then you need a system like SADiE.
So is SADiE worth the cost? This will ultimately boil down to how easy it is to use the software. You can get an indication of how intuitive a program is by giving it to someone who is not particularly at home with computers. Since I'm a fairly 'technical bear', I let a few people I know who are involved in the mastering side of the biz have a look at SADiE and they were all impressed by the naturalness of the 'user interface'. Speaking with Toby Murcott (of Omni Radio Productions in Bristol) confirmed that broadcast professionals felt the same way, quickly picking up the basics and becoming productive.
In my opinion SADiE is the bee's knees when it comes to audio post-production. I used the system both to master records and to compile a commercial 'talking book', and not only did I get the work done quickly but I had fun doing it. The SADiE software is powerful enough to do the job whilst still being simple enough not to get in the way. It'd be nice if SADiE could be more effective in a pre-production environment (I'd love to slave to my multitrack and gain four or eight extra tracks, for instance) but not if it's at the expense of the post-production facilities or its 'usability'.
Anyway, I must rush. I've got an appointment with my bank manager about buying a hard disk recorder!
Further Information
From £2,700 inc VAT.
Studio Audio & Video Ltd, (Contact Details).
About The Author...
Brian Heywood has a Masters from the Music Department of City University and uses PCs professionally in audio production as well as providing consultancy in the musical applications of the PC. He is co-author of the PC Music Handbook (available from the SOS Bookshop) and is a technical consultant to the UK MIDI Association. Brian can be contacted via email on CIX as (Contact Details) or on PAN as BRIANHEYWOOD.
Browse category: Software: Hard Disk Recorder > Studio Audio & Video Ltd.
Review by Brian Heywood
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