PC Hard Disk Recording Requirements

The PC‑owning community now seems to be split into two camps — those who already record onto hard disk, and those who would like to, but have yet to work out what equipment they really need. Martin Walker guides you past the pitfalls and perils.

First things first — don't expect to turn to the end of this feature and find a shopping list. There are now so many hard disk recording packages that it is impossible to define a perfect system that will suit everyone. What this feature will do is provide enough background for you to make your own informed decision, as well as pointing out freely‑available utilities that allow you to check the performance of a particular hard disk recording system with an existing computer setup.

Music retailers (and the SOS offices) are besieged with phone calls from people either asking for advice on what equipment they really need, or help with problems that they encounter after buying equipment that they thought they really needed. The fundamental problem here is that rarely does a package get assembled by one person, either a specialist music dealer or computer retailer. Normally, either the computer has already been set up and the software added at a later date, or all the facilities are added piecemeal over a number of months, or even years. In essence, hard disk recording simply requires a computer with a hard disk and a soundcard. However, in order to get these running side by side and in harmony, many other considerations also need to be taken into account: not just the soundcard, but the MIDI and audio drivers provided by its manufacturer, the facilities and speed of the PC and its hard disk, the way the operating system is set up, and the capabilities and requirements of the software package.

But That's What It Said On The Box!

In the past, many software manufacturers have been rather optimistic when specifying minimum requirements for PCs used with their package. These people would recommend a couple of tin cans and a long piece of string as the minumum requirement for a communications system, and this is partly why many people have come a cropper — they end up installing software on a machine that is not quite up to the task of running it. But probably the biggest single reason why so many people have problems is simply that the PC was never designed for hard disk recording, and particularly not with the Windows 95 operating system. Best results are often achieved by switching off some of the custom settings which normally improve performance in most other types of software, such as word processing and graphics packages. Such software tends to be optimised for quick bursts of disk activity followed by lots of computation, whereas hard disk recording requires a machine to be set up so that it performs best when continuously writing to the hard disk. Disk caches, for example, normally store the most recently accessed data in case it is requested again (giving a very rapid retrieval), but with hard disk recording, this never happens — the data is continuously being written to and then read from the hard disk, so the cache settings need to be switched off.

Ultimately, performance of any hard disk recording system is determined by the weakest link in the chain. In an ideal world, the maxim 'the faster the better' always applies, but in the real world, there are various measures you can take which will ensure that whatever PC you have, it is optimised as far as possible for hard disk recording. This may, in the case of a lower‑powered machine, make the difference between being able to record a couple of audio tracks alongside MIDI data, and not being able to record audio at all. In the case of higher‑spec machines, a simple tweak of the appropriate computer parameters may often achieve playback of an extra channel of audio if the timing is currently borderline. For these reasons, whatever the power of your PC, it is well worth spending some time optimising your machine so you can realise its maximum potential.

Processors

Hard disk recording tends to fall into one of two categories — the first and easier route (albeit more expensive initially) is to use a stand‑alone package such as Soundscape, which contains all of the hardware necessary for hard disk recording, including the hard disk, in a separate unit. The PC acts as the front end, and is in control, but the bulk of the processing horsepower resides within the Soundscape box, with the result that a relatively low‑spec PC can be used as the front end, as the demands on it are not too great.

The second course is to use the PC's integral hard disk in conjunction with a more highly specified soundcard, and control hard disk recording entirely from the PC, using internal software such as Cubase Audio or Logic Audio. This approach requires a much more powerful PC, since everything is being done by the computer — nowadays PCs with Pentium processors reign supreme in this field. There are still plenty of perfectly usable PCs with 486 processors in use, and for stand‑alone recording systems like Soundscape, such machines are perfectly adequate. However, Windows 95 is now a year old, and manufacturers are all moving over to this operating system despite their initial reluctance. I personally share Janet Cook's view (see page 176) that Windows 95 is the way forward for the PC, and despite Windows 3.1 proving to be easier to use for hard disk recording in many cases, I think most future software packages will eventually turn up in a '95‑only' 32‑bit version. Even if you are perfectly happy with your current setup, I think there will come a time when Windows 3.1 software will no longer be supported, so an upgrade to Windows 95 is a question of When rather than If.

A fast 486 processor will run Windows 95 happily enough (most music software manufacturers now specify a minimum of a 66MHz 486DX2) but 16Mb of memory is a must. You can try to run with 8Mb, but you will not be a happy person for long! Upgrading memory from 8Mb to 16Mb with a 486 motherboard is likely to cost double the equivalent upgrade with a Pentium motherboard, since SIMMs (Single In‑line Memory Modules) have now changed from 30‑pin devices to a cheaper 72‑pin version, and this is standard on machines with Pentium processors. If you have a 486 machine with 8Mb, think long and hard before you spend any more money on it (but see the 'Stick Or Twist?' box above for a suggested easier upgrade path).

Hard Disks

There are two basic sets of choices to make before buying a hard disk for audio recording — whether you buy internal or external drives, and whether they are fixed or removable. The difference in price between an internal and external drive for a particular capacity will be about £75 (for the case and power supply of the external drive). The advantage of a removable drive, particularly the latest 1Gb devices such as Iomega's Jaz, is that each project can be completed on a different cartridge, allowing quick changes without having to back up an entire CD's‑worth of audio material and then reload another project from a different DAT tape (all often in real time — ie. an hour's music takes an hour to back up). You can cart an external drive around to other studios if need be, but DATs are far more portable for this purpose if you only need to load the data in once. The main things to watch out for when shopping for a new hard drive are sustained transfer rate and access speed. Commonly, drive manufacturers quote speed using burst access rates. These rates are the disk equivalent of speeds quoted for dragsters, and are a fine guide to performance if the drive is intended for use with 'ordinary' software, ie. business or word processing packages, which, as already mentioned, access the drive in short read/write bursts. For audio recording purposes, the sustained transfer rate is more important, which could be likened to the kind of rate you get from a double‑decker bus — the bus is not as fast as a dragster, but it's capable of slogging on for hours carrying many tracks of audio without ever stalling or forgetting to pick up a new signal! The access time is also crucial, since during simultaneous recording and playback on a multitrack system, the hard disk will have to keep shooting off to read data from different parts of the disk for each playback channel, as well as jumping back to write new chunks of recorded data. Each time a new area is accessed, it takes a finite time for the drive to hurl itself to the appropriate place before starting to read or write.

Many software manufacturers would recommend a couple of tin cans and a long piece of string as the minumum requirement for a communications system.

Emagic helpfully specify a minimum specification for a drive used with Logic Audio — a 1Mb per second transfer rate and an access time of 10 milliseconds. Along with a minimum 90MHz Pentium processor and 16Mb of memory, this will ensure a good performance. The company claim to have undertaken extensive PC testing to ensure that these figures are realistic, so that you can have confidence that such a system will not fall over. Other software manufacturers such as Steinberg (Cubase Audio) and IQS (SAW/SAW Plus) make utilities freely available which you can run on an existing machine to obtain a readout of the approximate number of simultaneous tracks possible on your machine. In fact, these programs will give you a fair idea of how your PC will perform with any hard disk recording package (see the screen dumps above left and on page 122).

Soundcards

Most software will work with any 16‑bit soundcard, as long as it uses a Windows Multimedia driver. In the past, several software manufacturers have squeezed more performance out of their packages by writing custom‑tweaked MIDI or audio drivers for popular devices. For instance, Steinberg supplied the initial versions of Cubase for Windows with their own MPU401 driver. This talked to the MIDI interface directly, without adding any overhead by using the Windows 3.1 interface, and was thus more efficient and less prone to clogging when dealing with vast amounts of controller or SysEx information. Nowadays, each hardware manufacturer provides a set of drivers that hook onto Windows in a standard way, so that every software package can access them all.

One factor that many people find out the hard way is that only a few soundcards are capable of recording and playing back simultaneously. This is known as Full Duplex operation, and is vital if you need to hear previously‑recorded tracks whilst you record additional ones. The default for many lower‑priced cards is Half Duplex, which translates as 'capable of either recording or playback, but not both at once'. If your card is one of these, you can still work around the limitation if you play back MIDI sequenced tracks as well; these will help to keep your recording 'in sync'. Subsequent playback will mix all previously‑recorded tracks down to a single stereo output. Alternatively, you can use multiple soundcards, playing back tracks on one whilst recording on another. The main disadvantage with this method is that you have to go through the initial procedure of setting up several soundcards in one PC — which is never an easy thing to do!

Sometimes, new drivers are issued that add Full Duplex operation to an existing card. Creative Labs have recently issued Full Duplex drivers that work with the SoundBlaster 16 and AWE32 range, but these do have the limitation of 8‑bit playback whilst recording with 16‑bit resolution. A selection of soundcards are recommended by most software manufacturers as giving good quality audio performance. These include the SoundBlaster 16 and AWE32 in its several incarnations, a selection of Turtle Beach cards including the Tahiti, Multisound and TBS2000, and more upmarket devices such as Digidesign's Audiomedia III and Session 8 (both with Wavedriver), and DAL's CardD Plus. Until most people hear the audio quality of these latter cards, it is difficult to justify their much greater cost, but if you have ever heard the buzzes and hiss that can occur when you use a budget card (partly resulting from interference with the rest of the PC circuitry), I suspect that you would not want to master an entire album using such cards.

Windows 95 User Tips

Finally, here are a couple of tweaks for Windows 95 users that may help to optimise a hard disk recording system. There are a host of suggestions that may or may not help if you get clicks, pops, and hiccups on record or playback, but the following two are recommended by almost all manufacturers, and should therefore be the first port of call.

• READ AHEAD OPTIMISATION
  This is a mechanism used by Windows to speed up disk access by reading data from disk in larger chunks than are actually asked for, to anticipate the next access. Depending on your system, you may get improvements by selecting a different setting, or even by turning the read ahead mechanism off altogether. From within the Windows 95 Control Panel menu, select System. Click on the Performance tab and then on File System. Now drag the slider to a new position. I tried settings of 0, 16, and 32K on my system, as well as the default setting of 64K. Running HDspeed after each change showed a 48% variation in read speed, but in my case, the best result was using the default setting of 64K (see the above screen grab).
• SETTING A CACHE LIMIT
  The second tweak involves manually adding an entry to the SYSTEM.INI file under the already existing entry [vcache]. Windows has a cache system that holds recently‑used data in case it is needed again within a short period of time. Unfortunately, as more disk accesses are made, this cache becomes larger, and eventually program data has to be temporarily saved out to disk to make room for the ever‑growing cache. To stop this interfering with the continuous disk access required for hard disk recording, try the following. Using a text editor such as Sysedit (provided with Windows), load up SYSTEM.INI and add a new line immediately beneath [vcache] which reads 'maxfilecache=2048'. This ensures that the cache will never grow bigger than 2Mb, and will thus not generate more disk activity than is needed (see the SYSTEM.INI screen grab above). Good luck!