Topic: 24/96 of a 1974 master analog?

[Digital Quality]

Forgive me for reviving a dead thread. Did anybody else catch the interview of the guys from http://www.plangentprocesses.com/ on the GD channel last Sunday?? In 50 words or less; they are restoring audio from tape to correct for stretching, as well as limited wow and flutter capacities of analog tape recorders. One part of making an analog tape recording includes AC bias (typically about 120kHz). The machine runs a bias signal to the tape right before it lays down the signal you want to record. The bias signal helps "loosen up" the tape "magnets" so you get a better SNR with the desired signal. Well, this bias signal was generated with a very accurate oscillator, much more accurate than the wow and flutter specs of the recorder, and the plangent processes folks do the job of recovering the bias signal. Then they run the desired signal and recovered bias through a digital process that speeds and slows the music down based on errors in the bias frequency. In drastic cases where the tape has really stretched, this corrects warbling and pitch shift so they can fix up old movies, but even when the source is still relatively clean it can make a big difference in terms of depth and soundstage.

That really got me thinking about this discussion. These guys are a one-off boutique service right now but who knows what will happen in the future. It's entirely possible that this sort of thing will show up in the high end tools some day. If you archive at a high enough frequency and resolution _maybe_ you will be able to recover the bias later but if you stick to what is needed just for the audio portion, you'll be hosed. Anyway, I didn't want to fire up the whole debate again but it was such an interesting interview. I didn't check out the NPR interview on their web page yet but I bet that's pretty cool too.

[DSatz]

Steam Powered, in my reply about five messages up from here, I mentioned Jamie Howarth--Plangent is his project. He's doing amazing work and as I said, that's the only kind of reason I can think of to preserve inaudible high frequencies in a recording. Otherwise, they're nothing but trouble, and the only real question is how to get rid of them with the least harm to the audible signals.

--best regards