Audio Recording With Computer Sequencer

The recording studio inside the virtual world of the computer is real enough, but sometimes you have to treat it with care to get the best from it. Paul White offers a few tips on the subject.

Computers offer us MIDI, audio recording, mixing, virtual effects, virtual synths and CD manufacturing facilities, but it doesn't pay to take them for granted. The following tips will help you get the best out of your system, whether it runs on a Mac or PC, and most assume that you already have a system that's up and running. If you're planning to buy a PC system but aren't sure what to go for, check out the FAQs on our web site and give some serious consideration to buying the system preconfigured from a single vendor rather than assembling it yourself. If you want to buy a Mac system, either buy one of the newly obsoleted grey Macs or wait until the peripherals and software copy protection needed to work with the new candy-coloured Macsn are ready. In either case, buy the fastest machine you can afford - even if you can't afford it!1. Optimise your input signal level at source rather than relying on normalisation to bring the level up: if your signals peak at only half the maximum level, you're effectively halving the signal-to-noise ratio of your recordings and wasting half of the theoretical resolution of your system. Digital processing such as EQ or reverb may also introduce far more noticeable rounding and quantising errors in low-level recordings. Use the level metering provided in the software and try to keep your peak levels just a few dBs below clipping.

2. Regardless of whether you have 16-, 20- or 24-bit recording, the real quality of your recording will be defined by the source. For vocals, consider buying a voice channel type of device that combines a good mic amp with EQ and compression. This may also be used when miking other instruments, and many feature an instrument DI input suitable for use with bass and clean electric/electroacoustic guitar.

3. The fact that computers and recording software are such good value for money can lead you into
believing you can make do with equally cheap components in the rest of the studio. This simply isn't true. With good capacitor vocal mics now available for under £200, there's no excuse for using your old gigging dynamic microphone.

4. Use quality monitor loudspeakers and set them up so that you're at the apex of a roughly equilateral triangle with the monitors pointing directly at you. You don't need to monitor loudly, but you do need enough volume to overcome the physical noise your computer fans and drives make.

5. Use a separate hard drive for audio if at all possible as this will increase the number of tracks you can play back at the same time. This also allows you to defragment, or even reformat, the drive regularly without disturbing your program files. Most modern drives are suitable for audio use, but if in doubt, get a drive that is badged as being suitable for AV applications. The faster the drive you buy, the more tracks you'll be able to play back, though very fast drives may need a special fast SCSI interface card to make the best of their capabilities. If you really can't afford a separate drive, at the very least create a separate partition on your main drive for audio use.

6. When choosing or upgrading a soundcard, try to get one that can provide at least four outputs - and a digital S/PDIF out if you own a DAT machine or Minidisc recorder. This way you can use one pair of outputs for tracks that use software-based plug-in effects while the other output can carry tracks that you want to effect using external processors.

7. Reverb is the most important effect in the studio, and good reverbs take up a lot of computing capacity. For this reason, it may be worth considering buying a soundcard with its own hardware reverb processing, such as the Lexicon Studio, the Yamaha DSP Factory or the Yamaha SW1000XG. The SW1000G also includes onboard synth sounds that can be patched through the same hardware effects as the audio tracks.

8. Unless you are using a fairly sophisticated soundcard with onboard DSP processing, you're likely to experience some latency or delay when monitoring the signal you're currently recording through the system (See Martin Walker's article on the subject in SOS April '99). The new ASIO II drivers will minimise this problem for compatible hardware, but it won't cure the problem in all soundcards. An alternative is to use a small mixer and arrange to monitor the computer's input rather than its output when overdubbing - a separate mixer will usually be needed to combine your audio and external synth/sampler signals anyway.

Monitoring the input source will avoid latency problems, but will mean you have to monitor without plug-in software effects. However, a simple hardware reverb unit is generally all that's needed to put you in the mood for a good performance, and you can probably make use of this when mixing if your card has more than two outputs.

9. Use Antares' Autotune plug-in not only to clean up vocal pitching, but also to tighten up guitar solos (a low-cost VST 'light' version is due very soon). As long as you set a slow enough tracking time, regular playing will be unaffected, but whenever you sustain a note, it will automatically settle on exactly the right pitch. This can be particularly useful for slow pieces that use a lot of string bends. You can also emulate that Cher 'Believe' vocal-type sound extremely convincingly by just setting the tracking speed to maximum and dialling in the correct key for the song rather than leaving Autotune on its Chromatic setting (although of course, Cher's producers claim Autotune was not used on that recordeing - see SOS February '99).

10. One problem that most guitarists come up against is that the computer's monitor interferes badly with the guitar pickups, resulting in a nasty buzz on the recording. Some humbucking pickups are reasonably good at rejecting this buzz providing you don't sit too close to the monitor while recording, but single-coil pickups tend to be very badly affected. One way around this problem is to switch off the monitor just before recording and use keyboard commands to start and stop the recording process.

If you can't switch the monitor off for some reason, sit as far away from it as possible when recording and rotate your position to find the null point where the buzz is least obtrusive. You might also use a noise gate pedal to keep your guitar quiet between phrases. Flat-screen LCD monitors are becoming cheaper and they both save space and eliminate the electromagnetic interference generated by the scan coils of a typical monitor. If you record a lot of guitar, or are short on space, such a monitor could be a good investment.

11. Physical noise is also a problem when miking instruments or voices in the same room as the computer. If possible, turn off unnecessary external drives, CD-ROM burners and so on, as these often make more noise than the main computer, Set up your mic (ideally a cardioid model) as far from the computer as possible and improvise an acoustic screen between the mic and the computer using a duvet or sleeping bag. Also make sure the surface the mic is pointing at is absorptive rather than reflective. Work as close to the mic as you can without compromising the sound (and always use a pop shield for vocals).

12. Virtually all sequencers capable of recording audio have a waveform edit page (though it isn't always called that) where it's possible to highlight and silence selected portions of audio. If background noise was a problem, you can sometimes improve matters by manually silencing all the gaps between words and phrases. This doesn't take as long as you think and can really improve the quality of a recording, especially where there are multiple audio tracks. It's a good idea to normalise your audio recordings before processing them so as to minimise rounding errors at the processing stage, though don't use this as a substitute for getting the record levels right in the first place. Normalising can generally be done from within the waveform edit page.

13. You can also use the Waveform edit page to clean up guitar solos. Often you may end up with an almost perfect take, but perhaps there's too much squeak or finger noise between notes, or maybe you caught the next string just after bending a note. You can use the silence function to surgically remove these little errors, though you may end up with a more natural sound if you leave them where they are but instead reduce them in level by between 6 and 20dB.

14. Try to record all parts dry - don't add reverb or delay unless you really have to. If you need to hear reverb to create a good performance, fake it at the monitoring stage, but don't record it. This way, you'll be able to edit tracks without cutting holes in the echo or delay effects you've added, then when the editing is done, add the necessary delay or echo, which will help hide your edits, making the recording sound quite natural.

15. Plug-ins always take up a certain amount of your computing power, so if you want to add the same delay or reverb-based effects to several tracks, use a single plug-in configured as an aux send processor rather than using a separate Insert plug-in on every track. You can use the Aux Send controls in the same way as those on a regular mixer to add different amounts of the same effect to any tracks you like, all for the CPU overhead of a single plug-in. Note that under normal circumstances, you can't use the aux send with processes such as EQ, compression or gating - these have to be inserts.

16. Often, it's cheaper to buy a hardware reverb unit or signal processor than to buy a decent plug-in that does the same job, and the chances are the hardware unit will still sound better. Don't try to force your software to do everything for you just because it can - very often you'll find you can get a better sound with discrete boxes, and of course they won't load your CPU. Even if you don't have a multi-output soundcard, you can still compress signals as you record them, ideally using a voice channel type of device as described earlier, and the same applies to EQ. Only the best digital Eqs sound as natural as even the most basic analogue equalisers.

17. There are lots of tricks you can do using the audio manipulation facilities provided by your sequencer. These vary from model to model; pitch-changing and time-stretching, which are invaluable for massaging audio sample loops, are supported by most machines. You may also find other tools for level maximizing, denoising and so on. Many of these work off-line, so you can use them even on a slower machine - you just have to wait around a while for the results.

18. Consider using CD-R to backup your audio files along with your song files. Though you can't rewrite a CD-R, they're so cheap now that it doesn't really matter. If you create a 600Mb partition on one of your drives and store (or copy) your audio and song files there, you can back up the entire partition in one go. Of course the same CD-R machine can be used to burn audio CDs of your finished songs.

19. Most computer audio systems run best if you get rid of any superfluous software such as screensavers and games – and make sure you have no more drivers than you actually need (Extensions for Mac users). The cleaner your system, the less likely you are to run into problems. Also, check manufacturers web sites to make sure you have the latest drivers as improvements are being made all the time.

20. Do some tests to find out how many tracks and plug-ins your machine can run without falling over, then try to work with no more than half to two-thirds this number. Most sequencers include some kind of CPU activity monitor to help you. The demands on your CPU aren't constant, and sometimes a lot of heavy processing loads can be imposed at the same time, which can cause a machine running close to its capacity to crash. Your disk drive will also slow down as it fragments, so try to allow for this - you can't be expected to defragment it after every track you recor