Seen those three little letters on a CD sleeve? You know, DDD, or AAD, that sort of thing. What do they mean?

Well, on the face of it, it's a very simple code to tell you how the CD was recorded at various stages. It was invented by an organisation in the United States called SPARS, the Society of Professional Audio Recording Studios. SPARS thought a code would be a good idea because, in the early days of CD, they were worried that critical listeners would blame poor quality on the studios and the CD medium, rather than the fact that record companies were using noisy old analogue source material — sometimes even making CDs by copying scratched old records.

So they came up with the three-letter code: the first letter would define the multitrack recording medium; the second letter the mixing medium; and the third the mastering medium; in each case A for analogue and D for digital. In theory, then, DDD means digital media throughout; ADD means recorded on an analogue multitrack, but mixed and mastered digitally; and AAD means analogue recording and mixing, mastered digitally. Actually, if you think about it, the last letter has to be a D — after all, if it wasn't digitally mastered, it couldn't be made into a CD.

The first letter is pretty clear too — a record has to be recorded using either a digital multitrack machine or an analogue multitrack machine.

The confusion arises with the middle letter.

Mixing a rock record wholly digitally, without recourse to an analogue mixer, for example, is still virtually impossible (discounting those of you who master direct from the stereo outs of your Synclavier). Indeed the only UK studio where you could do wholly digital mixing, CTS in north London, have just got rid of the big Neve DSD digital mixer that made such a scheme possible. With classical music and some jazz, where few channels are needed on a mixer, there is the possibility of mixing wholly digitally, using eight-and 12-channel digital mixers like those from Sony, JVC and Denon.

But rock records are often labelled DDD, despite the use of analogue mixers. So the inference that a CD marked DDD was produced wholly in the digital domain is nearly always inaccurate.

Some recording industry observers have therefore suggested a five-letter code for CDs and DATs. The first letter would remain the definition of the multitrack medium; the second would define the mixing console; the third would define the two-track transfer; the fourth the finished two-track master, with songs in the right order, any editing done, and EQ added; and the last letter would remain the D for final mastering. Most rock records recorded recently would therefore be DADAD, though with the advent of editing in the digital domain (Neve, again) the fourth letter could be a D in quite a few cases.

Here in the Making Music office we have our own single letter code, C or B. C means crap; B means brilliant. Much simpler, eh?