The first letter was the recorder used for initial recording, say a Studer A800 as an example of an analog multitrack or DASH as an example of a digital one).
The second letter was the recorder for the mixdown, i.e. usually some 2-channel system like an analog ATR-102 or Studer A80 or a digital DAT.
The third letter was the recorder for the master, which for CD by definition was always digital. In the early days usually a Sony U-matic, which funnily enough was an analog video tape format which got reused for digital audio (and is the reason for the odd 44.1 kHz sampling rate of the CD).
Edit:
The code was actually always considered a bit meaningless.
For example, you could record on a digital DASH, but mix on an analog SSL console and print the mix to a digital recorder. That would have been a DDD CD.
On the other hand, you could record on an analog A820, mix on a digital Studer desk, print the mix on an analog A80 and that would have been a AAD CD.
So, two codes indicating "pure" digital or "pure" analog, even though both processes used both technologies.
Or record on a ADAT and mix on a Yamaha 02/R, which would have been DDD but probably sounded worse than the AAD recorded on a Studer analog tape ;)
Comments
Close, but not quite.
The first letter was the recorder used for initial recording, say a Studer A800 as an example of an analog multitrack or DASH as an example of a digital one).
The second letter was the recorder for the mixdown, i.e. usually some 2-channel system like an analog ATR-102 or Studer A80 or a digital DAT.
The third letter was the recorder for the master, which for CD by definition was always digital. In the early days usually a Sony U-matic, which funnily enough was an analog video tape format which got reused for digital audio (and is the reason for the odd 44.1 kHz sampling rate of the CD).
Edit:
The code was actually always considered a bit meaningless.
For example, you could record on a digital DASH, but mix on an analog SSL console and print the mix to a digital recorder. That would have been a DDD CD.
On the other hand, you could record on an analog A820, mix on a digital Studer desk, print the mix on an analog A80 and that would have been a AAD CD.
So, two codes indicating "pure" digital or "pure" analog, even though both processes used both technologies.
Or record on a ADAT and mix on a Yamaha 02/R, which would have been DDD but probably sounded worse than the AAD recorded on a Studer analog tape ;)
3/4" tape and was the only tape format that had the take up reel on the left.