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DAT and 8 mm tapes use in-contact helical scan heads that actually deform
the tape and penetrate the plane of the tape. This can cause excessive tape
wear. Build-up of the residue on the head can result in a redeposit of the
previously-removed coating, scratching the tape. Powerful error correction
built into the formats usually recover the information, but there is a
significant risk for the archivist.

Jerry
Media Sciences, Inc.

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of Tom Fine
> Sent: Monday, February 19, 2007 7:11 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] DAT Archival Housing
> 
> Hi Parker:
> 
> I've done a couple hundred DATs total by now and have not seen the
> problems you describe. I have
> not, however, had any at 32khz. Most of mine have been 48K although some
> have been 44.1. I did have
> one where an unrecoverable glitch jammed up the sync with the DAW. What I
> did was rewind the DAT a
> little, get to the glitch plus less than a second, then pause, then start
> recording on the DAW, then
> play out of pause. Locked right up again with no problem. Was also able to
> find the same note that
> was glitched and repair the song in the DAW and the client was happy.
> 
> Don't  you think that, no matter what the problems or challenges, one with
> a collection of valuable
> material on DATs should transfer the material sooner rather than later,
> whether or not the DATs may
> or may not have whatever alleged shelf life? The reason would be, the
> playback equipment is fast
> submerging technology that is not easily revived nor will there ever be a
> market to revive it. In my
> opinion, it's a classic case why digital is so much better for format
> migration. Sure, there will be
> a certain percentage that is challenging to migrate, but most DATs (based
> on my experience and I
> think Richard's and others), migrate just fine and with no audible
> changes.
> 
> -- Tom Fine
> 
> ----- Original Message -----
> From: "Parker Dinkins" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, February 17, 2007 10:44 PM
> Subject: Re: [ARSCLIST] DAT Archival Housing
> 
> 
> > One of the problems with DATs is that there is no one machine that can
> play
> > all formats. For example, there was the 32kHz LP format (12 bit) that
> cannot
> > be played on some 32kHz capable machines. There were also two flavors of
> > time code, the regular SMPTE version, and LTC on the PCM-2000. The DA-
> 45HR
> > was a 24 bit machine, and there were probably other varieties as well.
> >
> > The problem with playing DATs digitally out to a workstation is that
> > workstations need some time to lock to the input; if a DAT has a sample
> rate
> > change or a surprise on/off/on cycle (and they often do), then the DAW
> will
> > usually choke, and lose much more program material than necessary.
> >
> > To illustrate, when we used to supply CD masters on DAT, we needed to
> supply
> > 120 seconds of digital black before first audio, and 30 seconds after
> last
> > audio. While not particularly on topic, this particular DAT format was
> > accepted as the cutting production master, provided it was striped with
> 30Hz
> > ndf time code and frame accurate start-of-track marks. It was, of
> course,
> > 44.1khz, 16 bit.
> >
> > We just preserved/reformatted/archivally re-recorded (take your pick)
> almost
> > 100 very informally documented DATs, and they all played beautifully -
> once
> > the proper format was discovered.
> >
> > Some of the biggest problems can occur with consumer DAT machines, and
> not
> > surprisingly, the least problems occur with the PCM-7000 series
> machines.
> > And there are still good high end machines to be found. Recently we were
> > able to find an unused PCM-7040 (with no hours) to replace a PCM-7050
> which
> > was destroyed.
> >
> > --
> > Parker Dinkins
> > MasterDigital Corporation
> > Audio Restoration + CD Mastering
> > http://masterdigital.com
> >
> >
> >
> > on 2/17/07 3:55 PM US/Central, Tom Fine at [log in to unmask]
> > wrote:
> >
> >> Richard is 100% right. And, unlike reels and disks and cassettes, it's
> hard to
> >> argue with any science behind you that you cannot get EXACTLY what is
> on a
> >> non-damaged DAT and put it on your hard drive, using a simple digital
> cable.
> >> If a DAT was recorded at 44.1K sampling rate, then the same can be said
> about
> >> a simple S/PDF or AES connection between a DAT machine and a CD
> recorder.
> >>
> >> So I can't see any reason to make a big deal about "preserving" DATs. I
> CAN
> >> see making a huge deal about transferring DATs to other digital media
> ASAP
> >> since DAT mechanisms are no longer made and it is a fast-submerging
> format
> >> that is unlikely to be usable in a decade or two.
> >