YOU GUYS are in different domains, RS is talking about analog music tapes and JM is talking about digital data tapes. The problems and handing of each is not the same.
-- J.C. O'Connell (mailto:[email protected]) Join the CD PLAYER & DISC Discussions : http://tech.groups.yahoo.com/group/cdplayers/ http://launch.groups.yahoo.com/group/cdsound/ -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Joseph McAllister Sent: Friday, November 20, 2009 3:31 AM To: Pentax-Discuss Mail List Subject: Re: OT: Vinyl vs. Digital On Nov 17, 2009, at 15:40 , Rob Studdert wrote: > the master recordings being tape however do degrade > with time. The ferrous binders often fail or become sticky so the the > tape flutters, the remnant magnetism becomes diminished so the noise > floor rises and dynamics become a little compressed. Plus old tapes > often suffer "print-through" which is an echo effect created due to > tape layers imposing their magnetic record on each other. It's > absolutely no surprise that old tapes sound worse years after they > were recorded. I had the pleasure of observing how the gov't (*military*) record to tape, and how they go about preserving the data on them. First off, I'm talking 70mm 48 track ferrous tape on 24" Pyrex glass reels. In the 80s. A raw tape is first run through one way and then rewound while passing the oxide side over a quartz prism edge to knock off any loose coating, while the backside is passing over a counter-rotating fine cotton cleaner that is itself a 9" reel to reel sub-system. The vacuum chambers on either side of the heads control the tape slack loops, and that air removes any dust or oxide that is not trapped by the mechanisms above. Once recorded, the tape is played twice to do a checksum on the data tracks, and a comparative check for variances in the analog signal that is recorded simultaneously on hard disk platter packs. Then it's stored properly. Every three months, the tapes were wound and rewound to repack them and prevent print-through or edge degredation. Every six months, the tape is taken out of storage, wound side to side, then duplicated to an identical reel of tape while being check summed against the original. The master tape is then cleaned and stored as a backup. The next time around, six months later, a dupe is made of the backup tape, then the master bulk erased. If that erased master test ok, it is re-used to record another session. It is never used to record a third time, no matter how well it tests. Because of the classified nature of the tapes, when it is thrown out it is bulk erased twice, shredded then burned on site. Keeps a half-dozen strong gentlemen employed 24 hours a day, year round, as the reels each weight 80 lbs.. It is most likely being done entirely digitally and stored on hard drives these days. And I guess my point is that the master and dupe backup tapes were never left to sit for more than three months. Joseph McAllister [email protected] The Big Bang was silent, and probably invisible. - from the Pentaxian's thoughts on particle physics, so far. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
