HARD CHOICES & SOFT OPTIONS

Choosing A Recording Setup: Part 1

Published in SOS July 1998
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Technique : Recording/Mixing

CHOOSING A RECORDING SETUP

PART 1: Confusing, isn't it? Where once the only recording option was tape, you can now put a whole studio inside a desktop PC or opt for an all-in-one recording and mixing hardware solution. Then again, you could stick to tape, or buy a separate hard disk recorder. In the first of this short series, PAUL WHITE examines the choices.

In the good old days of professional recording a studio was built around an analogue mixer, a 2-inch analogue multitrack recorder, a pair of monitors, and some outboard effects. The mastering medium was also analogue tape, and if the mix got too hard for one person to manage, you called in more pairs of hands to operate the faders.

These days, pro studios have changed surprisingly little, except that they probably have some form of mixer automation. In project studio circles, however, or in those areas of audio away from mainstream music recording, the technological options have expanded to the point that figuring out which is best can be mindnumbingly confusing; indeed, this was the theme of my April editorial. But the aim of this series is not to look at the problems this can cause, but rather to look at the more common recording and mixing options and to consider their strengths and weaknesses.

It may seem strange, but the odd little 4-track cassette decks with built-in mixers that started the whole home recording ball rolling never even got a proper name. Tascam called theirs Portastudios, while Fostex called their machines Multitrackers, but there's no generic term. Well, I'm going to call them 'cassette multitrackers' with a small 'm' and be done with it!

Cassette multitrackers still represent the cheapest way to get into multitrack recording, and their clear advantage, other than low cost, is their impressive degree of integration -- you get everything you need, apart from the microphone and mastering machine, in one box. Though 8-track cassette multitrackers are still available, they're less appealing than they used to be because of the aggressively priced digital alternatives, but their 4-track brethren are cheap, reliable, and make great musical sketchpads.

I know that some people have released commercial CDs based on material recorded on a cassette multitracker, but the truth of the matter is that cassette quality isn't really up to it. Unless you have one of the more expensive machines with Dolby S, the noise reduction is likely to cause some audible side effects, and even if the noise reduction weren't a problem, you'd still have the inherent wow and flutter and the compromised top end of the cassette format. Having a cassette deck that runs at double speed helps improve the audio quality, but it can never rival open-reel (see below). What's more, because you probably only have four tracks to play with, you'll probably need to bounce tracks at least once, and every time you bounce you lose a little more quality. However, a multitracker can offer all the basic functions necessary for music recording, functions such as punching-in and out on the fly, the ability to record multiple tracks in one take (though cheaper models may only record on two tracks at once), and track bouncing.

benefits

• Cheap, archivable medium (cassettes).
• Generally reliable and easy to maintain.
• Portable: some versions even run on batteries.
• Convenient: there's little wiring, and you can use a domestic hi-fi both for mastering onto stereo cassette and for monitoring.
• Very easy to use.
• Recordings store well if kept in favourable conditions.
• Mechanically quiet, though not silent.

disadvantages

• Sound quality not as good as open-reel analogue tape -- it's fine for demos, but not really up to mastering.
• Punch-in/out points are not seamless.
• A tape track is required to record timecode when sync'ing a sequencer.
• Mixer usually has insufficient channels for mixing MIDI sound sources, and both the quality and facilities will be poor compared to an average stand-alone mixer.
• Relatively slow rewind time.
• Difficult to edit.

Open-reel analogue recorders are available in a number of formats, from four tracks on quarter-inch tape to 24 tracks on 2-inch tape. For project studio use, the most popular formats are eight tracks on quarter-inch or half-inch tape, and 16 tracks on half-inch tape; also, just before analogue gave way to digital, both Fostex and Tascam produced some excellent 1-inch 24-track machines. Sadly, other than a few pro machines, analogue multitrack tape recorders are no longer built, although you can of course pick them up on the second-hand market.

Analogue machines generally offer high sound quality. Although not as technically accurate as the sound from a good digital machine, the non-linear way in which tape responds to high levels offers certain benefits -- it makes setting peak recording levels less critical than in digital systems, and confers on the audio a slightly compressed, warm sound. Audio quality depends to some extent on what type of noise reduction system is being used -- and unless you're running a pro machine at high tape speeds, noise reduction is a necessity. As with cassette, you'll suffer loss of quality whenever you bounce tracks, but this is less serious than with cassette.

Media costs vary from cheap (for eight tracks on quarter-inch tape) to very expensive (for 2-inch tape, especially if you opt for a 30 ips tape speed rather than the more usual 15 ips). Open-reel tape can be edited very easily with special tape and razor blades, and if it's stored properly analogue tape has a very long shelf life. Any deterioration tends to be progressive.

Because an open-reel machine is purely a recorder, you need a separate mixer, which leads to greater wiring complexity than with an integrated solution. Nevertheless, having a separate mixer and recorder allows the system to be more flexible, and to incorporate patchbays for connecting signal processors or for changing routing.

A high quality 2-inch multitrack running at 30ips without noise reduction will invariably produce a better sound than its digital equivalent, even though it may not be technically as quiet or have such a flat frequency response.

benefits

• Simple to use.
• Generally very good sound quality.
• Available in a number of formats depending on how many tracks you require.
• Reliable, with little risk of total media failure.
• Mechanically quiet, though not silent.

disadvantages

• Sound quality still suffers when copying or bouncing; there is also a slight deterioration in quality after repeated passes of the tape past the playback head.
• Punch-in/out points are sometimes not seamless.
• All editing has to be physical, via cutting and splicing the tape.
• One tape track is needed for a sync code if sync'ing a sequencer.
• Tape costs are high when using pro formats.
• Relatively slow rewind time.
• Tape storage can require a lot of room.

Digital tape machines use either special open-reel tape or cassettes, usually a type of video cassette. Open-reel machines tend to be priced such that only professional studios can afford them, so they will not be discussed here. However, machines based on video formats (frequently referred to as MDMs, or Modular Digital Multitrackers), such as the Alesis ADAT and DTRS, are very popular and have taken over from narrow-format open-reel analogue machines in the serious project studio market as well as in a number of professional applications.

On the face of it digital tape is wonderful -- the hardware is affordable, the media costs are exceptionally low, and the sound quality is equivalent to that of CD or DAT with low noise and a ruler flat frequency response. What's more, multiple machines can be synchronised if you need more tracks, and it's possible to copy tracks, or even whole tapes, in the digital domain with no obvious loss in sound quality.

The reality is that these digital systems aren't as reliable as analogue, because when a media or hardware alignment problem occurs, the error correction system simply works harder to restore the corrupted data, and when the problem gets worse, it will resort to making up data to fill in for missing samples. Further deterioration, however, will cause very audible dropouts on replay. One day everything sounds fine, the next you may have a catastrophic failure -- there's no advance warning. Playback errors can also occur when tapes made on one machine are played back on another which is aligned differently. With analogue machines, misalignment usually results in a loss of top end, and possibly level, but in the digital domain, the whole playback process breaks down. Also, as we all know from domestic VCRs, after a while the cassette reels start to stick, and the picture becomes grainy as the tape sheds oxide. Special formulations of tape and shell design are used for digital audio, but these problems are not entirely eliminated.

Another problem with MDMs is that when two or more machines are running in sync, it takes a finite time, often several seconds, for the slave machines to lock to the master. This is very irritating when performing multiple drop-ins, and it can completely destroy your creative flow. On top of this, the varispeed range of digital tape machines tends to be less than for analogue, you can't turn tapes over to make them play backwards, and the cleaning process isn't as simple as for analogue machines.

To finish on a more positive note, however, providing the machine is fitted with a suitable interface, you can generate MTC or MIDI Clock (for sync'ing a sequencer) without sacrificing a tape track, and with two or more MDMs, you can manage quite sophisticated compilation editing by offsetting one machine against the other, then copying tracks in the digital domain. And, saving the best until last, MDMs punch in and out completely seamlessly.

benefits

• Clean, quiet sound quality.
• Tracks or whole recordings can be cloned to a second machine with no loss of quality.
• Multiple machines can be sync'ed together when more tracks are needed.
• Media cost very low.
• Physically less noisy than computers or hard disk drives that include cooling fans, but a little noisier than most analogue tape machines.
• Good compatibility with other studios as there are only two main formats (DTRS and ADAT). The new 20-bit ADAT Type II machines can still play and record older Type I tapes but not vice versa.

disadvantages

• Long lock-up time when using multiple machines.
• You still have to wait for tape to rewind, though MDM is faster than analogue.
• Failures due to media damage or machine misalignment are likely to be sudden and catastrophic.
• Physical tape splicing not possible.
• Some say the sound is 'cold' and 'clinical' when compared to analogue.
• Recording levels must not exceed the 0dB point, as they can with analogue, because digital clipping sounds very nasty.
• MDMs tend to run at a 'hotter' signal level than analogue machines -- +4dBm on the analogue ins and outs may correspond to signal levels of -12 to -15dB on the MDM meters. This can lead to interfacing problems with analogue mixers.
• Some MDMs have noticeably noisier mechanics than their analogue equivalents.

One alternative to analogue or digital tape is the tapeless digital multitrack recorder, in which a digital recording is stored on a hard disk drive of the same type used by computers. Hard drives are less prone to errors than tape, and because the head never actually touches the surface of the disk, there's no appreciable wear other than to the spindle bearings.

Unlike tape, which is a linear medium, recordings made on hard disk can be accessed almost immediately -- there's no waiting to rewind, so with a little clever RAM buffering it's possible to play back sections from anywhere on the disk in any desired order without gaps or glitches. This random access capability of hard drives makes them perfectly suited to non-destructive editing. For example, you could record instruments or vocals for a chorus only once, but repeat them whenever a chorus is needed.

Hard disk drives are reasonably reliable, though when one does crash it's quite likely that all the data stored on it will be lost, not just a part of it, as is the case when a tape gets tangled in a machine. Furthermore, once the drive is full -- and remember that audio recordings made at a 44.1kHz sample rate use up around five Megabytes of drive space per minute per track -- you have to find a way to back it up before you can re-use the drive, and this usually means transferring the data to a removable media (such as a Jaz drive) via SCSI, or backing up to DAT via a digital output port, which may be a slow process. Two tracks can be backed up to DAT in real time, four tracks take twice as long, and eight tracks take four times as long. What's more, it'll take you the same time to load the data back onto the drive when you want to resume work. That means a half-hour, 8-track recording will take two hours to back up and another two hours to restore. Backing up to a removable drive is faster, but the media cost is high compared to DAT.

While random access is one of the great benefits of hard disk, it also makes navigating through your material less intuitive. Open-reel tape has certain mechanical dynamics, so it soon becomes second nature to spin back 10 seconds in readiness for a punch-in, but with hard disk recording, you're 'flying on instruments' all the time. What's more, though most machines will allow you to punch-in on the fly, you may find that you can't do multiple punch-ins and outs without stopping the recorder each time. This is very frustrating when you're trying to patch up a vocal track as the traditional way is to leave the tape running with the singer singing along, then manually punch in and out each time a section has to be replaced. Recording with real musicians has a natural flow to it, and no matter how clever the technology, if it interrupts the natural flow it's getting in the way of you doing your job.

On a more positive note, punching in and out on a hard disk recorder is likely to be gap and glitch free, and there's usually at least one level of undo so that an unsuccessful drop-in or recording can be restored to its original condition. Another useful feature found on many machines is the ability to record virtual tracks. These are, in effect, alternative takes stored on different parts of the drive; when you play back, you can decide which one to use. For example, you could play three different guitar solos, storing two of them on virtual tracks, then pick the best when you come to mix.

The sound quality of a hard disk recorder is determined by the sample rate, the number of bits, and the quality of the converter circuits. Most stand-alone digital recorders use uncompressed audio (see 'Audio Compression' box). Depending on the model, it may be possible to record on all tracks simultaneously or only on a limited number.

benefits

• Doesn't increase the burden on your computer, which can be left to concentrate on MIDI sequencing.
• Because the converters are in a hardware box and not on a computer card, there's a better likelihood of low crosstalk and noise.
• Easily integrated with a conventional mixer.

disadvantages

• Costs more than a 'native' PC audio system (see next month's instalment for more on this).
• The hard disk drive may be noticeably noisy, which is a problem if you record in the same room.
• More wiring is involved than with a PC-based recorder/mixer or integrated digital multitracker.
• There are numerous different systems that can lead to serious compatibility problems when moving projects from one studio to another. Most file formats can be converted, but this takes time.

The new generation of digital multitrackers build on the concept of the analogue cassette multitracker. A mixer is therefore included, which may be either analogue or digital (there's an increasing move towards built-in digital mixers, as this makes it easier to add automation), and it's also common to build in high-quality digital effects. The main alteration, of course, is the replacement of the cassette multitracker's tape drive by a tapeless digital storage system capable of recording four, eight or even 16 tracks to an assortment of fixed and removable media. Fixed systems used conventional hard drives while removable media systems tend to use Jaz drives, Zip drives or Minidisc. As a rule, the removable drive systems rely on audio compression to increase storage capacity and to maximise the number of playback tracks, while fixed drive systems use uncompressed audio.

The benefit of a built-in analogue mixer is its familiar 'one knob per function' format, and the low cost at which additional inputs and insert points can be added. Its disadvantages are that automation isn't practical, and every time a signal is bounced, it has to be converted from digital to analogue and then back again.

Built-in digital mixers keep everything in the digital domain, and it's relatively easy to automate EQ, pan and level as well as aux send levels and even effect types. On simpler systems the automation may be of the 'snapshot' type, storing a series of console settings that can be switched at the appropriate point in a song. On more upmarket models, it may be possible get full dynamic automation via either an internal automation system or control from a MIDI sequencer.

One disadvantage of digital mixers is that it's seldom practical to provide one knob per function, so the operating system is less intuitive than for analogue mixers. Furthermore, additional inputs, outputs or insert points require expensive A-D and D-A converters, so cost-effective models are likely to have quite limited analogue I/O facilities.

From what I've seen so far, removable media digital multitrackers are very attractive as they offer excellent sound quality, sophisticated mixing facilities, good onboard effects, and they can be used to lock up a sequencer via MIDI Clock or MTC. Given the problems that many people experience with digital audio on computers, using a digital multitracker in combination with a computer or hardware sequencer is very attractive.

benefits

• Takes up relatively little space.
• Recorders based on removable media avoid the backup problem.
• Sound quality can be very good, with very low noise.
• Minimum of wiring or external equipment needed.
• Easy synchronisation to MIDI sequencers.

disadvantages

• Recorders based on removable media tend to have a very limited recording time.
• Removable media storage systems evolve so quickly that existing drives are likely to be superseded by higher-capacity devices before long.
• Digital mixer sections can be complicated or time consuming to operate.
• Audio data compression may not be acceptable for certain applications.
• Cannot be expanded to give more tracks.
• Fixed-drive systems tend to generate more mechanical noise than analogue tape machines. Some removable-drive models tend to be quieter, though large-capacity removable drives may also be quite noisy.

Next month, I'll be looking at the pros and cons of entrusting your entire recording, mixing and sequencing requirements to a computer-based desktop system.

Recording Options: Choosing A Studio Setup Part 1

Recording Options: Choosing A Studio Setup Part 2

Recording Options: Choosing A Studio Setup Part 3

Recording Options: Choosing A Studio Setup Part 4

Recording Options: Choosing A Studio Setup Part 5