BURNING ISSUES

Compiling An Album On CD-R

Published in SOS July 1999
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Technique : Recording/Mixing

Up to 30 percent of SOS readers are planning on buying a CD recorder this year, so clearly many of you have designs on making your own album. Paul White talks you through the process of compiling an audio album on CD-R using a stand-alone CD recorder fed from a DAT source.

CD-R recorders and blank CD-Rs are now so inexpensive that it's more cost-effective to archive finished mixes to CD-R than to DAT -- or even decent analogue compact cassettes! CD-R also provides an excellent medium for compiling your own albums in a form that can be tried out on other people's sound systems without bringing the variables of cassette tracking and noise-reduction calibration into the equation. And, best of all, a number of commercial CD-pressing plants are able to work from properly recorded and PQ-coded CD-Rs, which can save on mastering costs. The purpose of this article is to offer you some guidance on recording your finished mixes onto CD-R so that you end up with something that sounds like a commercial album.

Strictly speaking, your original material should be recorded at a sample rate of 44.1kHz unless you're prepared to make the transfer to CD-R in the analogue domain. However, there are inexpensive sample-rate converters that can be used in situations where keeping everything at 44.1kHz is not possible, and many of

"It's perfectly possible to compile an album onto DAT (or Minidisc) using the Pause button between tracks. This doesn't give the same degree of timing precision that can be achieved with a computer editor, but if you're careful it can be close enough."

the better CD-R recorders have a sample-rate conversion facility built in. This makes it possible to work from consumer sources with a fixed 48kHz sample rate with no appreciable loss of quality.

How you approach compiling your finished album depends on the equipment you have available. Computer-based editors tend to be the most flexible, but you don't have to use one. Even if you do edit your audio tracks on a computer, it's often more convenient to run the file out to a DAT machine before burning a CD on a stand-alone recorder, as this gives you the opportunity to verify that the track ID markers are in the right place, and to move them if necessary.

It's perfectly possible to compile an album onto DAT (or Minidisc) using the Pause button between tracks. This doesn't give the same degree of timing precision that can be achieved with a computer editor, but if you're careful it can be close enough. Always record past the end of each track by several seconds, then wind the tape back to find the end of the audio before putting the recorder into Record/Pause mode ready to capture the next track. This ensures that the DAT subcode track will be continuous. This is important, as the subcode tracks contains the sample-rate clock, as well as the track IDs, and if your aim is to make a commercial product it's important not to have any discontinuities in the subcode. Compiling in this way can be done from DAT to DAT or from DCC or Minidisc to DAT. My technique is to have the source track cued up in pause mode, before putting the target machine into record as soon as the previous track has ended. I then count the gap time manually before hitting the start button on the source machine.

Always work in the digital domain if you can, unless you're using some form of analogue processor to sweeten the mix as you transfer. If you're going via analogue, keep a close eye on those record levels, as digital recorders are most intolerant of clipping. A fast limiter can help here.

Before moving on to the next stage, it's worth considering the relative levels of the tracks on your master tape and the pause lengths between them. It's no good setting all the tracks to reach the same peak level, because the chances are that they'll still sound out of balance. The right approach is a mixture of feel and experience, but listen in particular to the vocals and the rhythm section. The voice will normally be reasonably consistent in level from track to track, even if one song is a ballad and the other a thrash metal track, but what I try to do is imagine whether the vocal sounds closer or further away in comparison with the tracks either side. The ideal balance is when you can imagine a band on stage moving from one track to the next without the sound appearing to get closer or more distant. If your tracks have been compressed or limited, it will probably mean that the louder tracks show 3 or 4dB more level than the quieter mixes, but that's fine so long as they sound even. For tips on how to treat your mixes at the mastering stage, check out the '20 Tips on Mastering' feature in the February 1999 issue of SOS.

Of course, there's no way to make level changes if you're working entirely in the digital domain -- unless you have a digital sound-processing device that provides gain control as part of its functionality. For most people, this means getting the balances right when mixing to DAT in the first place, but now that so many digital

Let's Be Careful Out There: A Few Precautions     BLANKS: CD-R blanks are now very cheap, so it doesn't make sense to buy bulk unbranded discs of unknown provenance when you can buy reputable branded discs for a few pence more. Handle the blank discs carefully, by their edges, and check the surface of new discs for dust or manufacturing flaws before using them. Dirt causes far more problems at the recording stage than it does when playing back. A can of compressed air (normally used for lens or slide cleaning and available from your local photographic store) is useful for blowing away dust prior to recording. CABLES: Another sensible precaution is to use a proper digital transfer cable between your DAT machine (or Minidisc player) and the CD-R recorder. Audio phono cables may appear to work, but they don't have the correct impedance, which can lead to clicks and glitches appearing for no apparent reason. Use a pukka digital cable and keep it as short as possible to minimise this type of problem. BAD VIBRATIONS: During recording, both the DAT player and CD-R machine should be solidly supported and free from vibrations that might introduce errors. Standing them on your sub-bass cabinet is not a good idea, and even monitoring loudly while recording is not recommended. LABELLING: Some CD-R disc manufacturers recommend you don't use adhesive labels. I can see why this would be a problem for high-speed CD-ROM players, as a badly positioned label can throw the disc out of balance, but I've had no problem with commercial CD labels used on audio CDs. The adhesive is designed not to attack the material from which the CD-R disc is made, but cheap unbranded discs may be more susceptible to problems than premium brands. Note that these labels are very thin, so any lettering on the original disc tends to show through. If you're in the habit of using labels, buying branded discs with an unprinted white, gold or silver label side helps enormously.

effects units come fitted with S/PDIF I/O, it's often possible to rig these up to work as digital volume controls. In this case, the processor must be set to external digital sync and patched between the source and target recorders using short cables.

Setting the right gap length between tracks is also a matter of feel, but as a general rule atwo-second gap will work after a song that ends with a fade-out or a long reverb decay, whereas a song that ends abruptly will probably require a three- or four-second gap after it, especially if the following song also starts abruptly. You should also consider the album's playing order from an artistic point of view -- it's usual to maintain dynamics by mixing musical styles rather than, for example, lumping all the slow songs together. The start and end tracks are particularly important: the first track should win over the listener as quickly as possible, while the last track should leave them wanting more.

Before recording to a stand-alone CD-R recorder, check all the start IDs on your DAT tape. Obviously, every track should have its own start ID, but there may be occasions where you've crossfaded two tracks and need to add a start ID during the crossfade where the DAT machine didn't add it automatically. This is easy to do manually.

Most DAT machines create their start IDs based on signal level, so technically speaking they're all slightly late, as the sound has to start before an ID can be created. The delay is small, but some CD-R machines take a while to start recording (when set to CD Sync mode) after the first ID is recognised, so it's a good idea to move the very first ID to a position a second or so before the audio starts. This involves first erasing the old ID, then writing a new one. The technique is explained in your DAT machine manual, but normally involves stepping through the ID mode to find Erase Start ID, then pressing Execute when the tape is stopped somewhere during that ID. Adding a new ID usually entails selecting Write Start ID and pressing Execute at the appropriate time while the DAT is playing. Both when erasing and writing IDs, it is important to leave the tape running until the Start ID indicator in the DAT display stops blinking -- IDs are several seconds long. If you don't do this you may end up adding incomplete IDs, or leaving parts of an old ID intact. I have known CD-R recorders recognise an ID that has only been partially erased, so be meticulous here. Commercial CD players may also take a fraction of a second to pick up when you select a new track, so just to be on the safe side I tend to move all the remaining track IDs to a quarter of a second or so before the actual audio start point. You may also want to re-number all the start IDs once you're done; this is usually as simple as pressing the Renumber button and waiting for the machine to do the job for you.

If SCMS (Serial Copy Management System) is preventing you from compiling your DAT, or if the CD-R recorder says that the master DAT is copy-protected, you have two main alternatives: either go via the analogue connections (which affects the sound less than you might think) or use a processor with an SCMS stripper built in. Friend-chip make units that do this job simply and inexpensively (see, for instance, the review on page 226), and there's nothing illegal about using these devices providing you're working with your own material.

You're now almost ready to burn that CD-R, but before you do, check the manual to see how your CD-R

"CD-R recorders and blank CD-Rs are now so inexpensive that it's more cost-effective to archive finished mixes to CD-R than to DAT -- or even to analogue compact cassettes!"

recorder reacts to silent passages such as the gaps between tracks. Most machines have an auto-stop function that can't be overridden, often preset to around eight seconds. The purpose of this feature is to stop the recording process after the album has ended, but it does make life very difficult if you're one of those people who wants to add a bonus track at the end of the album after a one-minute pause. You may also find that some very quiet classical passages are interpreted as silence. There's no neat way around this, but I know at least one person who adds low-level, low-frequency tone bursts to long gaps in order to keep the CD-R machine running. A 20Hz tone at -45dB may be all that's needed, and on most replay systems this will be quite inaudible.

To burn your CD-R, use CD Sync mode (multiple tracks as opposed to 'single track, then stop' mode!) so that your DAT IDs are automatically converted to track start IDs. If the disc is to be used as a master for commercial production it's also important to burn the entire album in one go rather than pausing or stopping between tracks. Pausing or stopping results in the laser switching off, and because this takes a finite time, errors tend to be generated during the pauses. The error-correction routines on a commercial CD player will normally hide these from you, but the equipment at the CD-pressing plant may deem them too serious to allow through the system.

Once you've got your album on CD-R, listen very carefully for clicks, glitches or other errors before making further copies. This is doubly important if you're tooling up for mass production. Check the sound on as many sound systems as you can and get accurate track timings to use on your sleeve notes. You should be able to read these directly from your CD player as the album plays through. When you're happy that the album is as near perfect as it's going to get, make further copies by taking the digital output of a regular CD player directly to the CD-R recorder. This is the easiest way of working and saves wearing out your DAT master. Happy duplicating!