Re: [ARSCLIST] Risk assessment tool Q3--DAT

[Jerome Hartke <jhartke@xxxxxxxxxxxx>]

Several years ago, Media Sciences conducted 4 mm DAT and 8 mm helical scan
tape testing for a number of clients. Tests were conducted in accordance
with the ISO standards. Results showed that both parameter and error
characteristics of many name brand "good" tapes did not conform to the
standards. Of course, this can also be true of optical media.

Tape wear characteristics showed "plowing" problems. Repeated back-and-forth
passes over the same section of the tape caused coating particles removed
from the surface to accumulate at the beginning and end of the test region,
eventually resulting in severe errors. Clumps of these particles could
become embedded in the tape because of the pressure inside the pancake.

Head clog problems were also observed when clumps of these particles became
trapped in a head gap. Sometimes these could be removed by cleaning, but the
heads became permanently damaged at other times. Tape damage was also
observed that resulted from head clogs.

Helical scan tape heads rotate at very high speeds, while linear heads
travel at much lower velocities. This may be important if tapes are to be
played more than 10-100 times during their lifetime.

Optical media may have disadvantages, but operation and storage is
non-contact, and the above tape degradation methods would not occur.

Jerry Hartke
Media Sciences, Inc.

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx] On Behalf Of Casey, Michael T
> Sent: Tuesday, January 10, 2006 4:42 PM
> To: ARSCLIST@xxxxxxxxxxxxxxxx
> Subject: [ARSCLIST] Risk assessment tool Q3--DAT
> 
> Hi,
> 
> Again, I very much appreciate the responses to my last two posts.
> 
> Here is the last set of questions, concerning DAT:
> 
> 1. What problems are encountered in transferring DATs?
> 
> 2. Have you noticed tape deterioration with this format?
> 
> 3. Are there any brands that are more problematic than others?
> 
> 4. Are there problems with thinner tapes (probably 120 minute or above)?
> 
> 5. Playback compatibility problems between machines?
> 
> 6. Have you noticed any age-related problems?
> 
> 7. If you had to choose between preservation transfer of a DAT tape from
> the mid-1990s, an open reel tape with sticky shed, an acetate-based open
> reel tape from the late 1950s, or an audio cassette from the 1970s,
> which would you choose and why?
> 
> [Assume that the content is different on each but each has been rated as
> equivalent in value. Assume also that you are conducting a visual survey
> of your collection and you have no further information on the individual
> recording. Therefore, your choice is based solely on what is known about
> how the format itself deteriorates and the risk that it represents, or
> on factors relating to the obsolescence of the format.]
> 
> 
> Thanks!
> 
> Mike
> 
> --------------
> Mike Casey
> Associate Director for Recording Services
> Archives of Traditional Music
> Indiana University
> 
> micasey@xxxxxxxxxxx
> (812) 855-8090
> 
> Co-chair, ARSC Technical Committee