Audio Recording with Computer Sequencers

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 Macs
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

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 record.

My Tonez
Signal Processors