Re: [ARSCLIST] Old reel to reel 'echo' problem

[Eric Jacobs <EricJ@xxxxxxxxxxxxxxxxxxx>]

Hello Melodie,

You are hearing what is called "print-through".  There are numerous
references on-line, for example:

http://www.aes.org/aeshc/docs/3mtape/printthrough.pdf

The recommendations on page 1 of storing tails out is the best
recommendation to minimize future print-through.  If the tapes
are two-sided (ie. Side A and Side B), then there is no head or
tail to speak of on the tape and you risk noticeable print 
through on one side or the other.

Alas, there is not much that can be done about existing print-
through aside from rewinding the tape and hoping that will 
reduce the print-through sufficiently (per the above document).

Well, almost nothing that can be done.  There is a process called
"skimming" - it's fairly exotic, and briefly discussed on my
website at

http://www.theaudioarchive.com/TAA_Tape_Studer_A820.htm

I quote:

   "...but also an exotic function such as skimming can be 
    programmed. The latter can be used to activate a slight bias 
    during reproduction in order to minimize the copying effect 
    of tapes that have been archived for a long time.

    The Audio Archive: There are only 3 STUDER machines that 
    have the skimming capability: STUDER A820 MKII, A812 MKII, 
    and A816. Studer was the only manufacturer to build this 
    capability into their machines. Note that print-through 
    erasure was patented by R. Herr of 3M (US Patent 2861133, 
    filed 1949 Aug 01, granted 1958 Nov 18). In essence, 
    skimming works by erasing the printed field in the smaller 
    improperly oriented oxide particles on the tape, while not 
    greatly affecting the field recorded in the longer, properly 
    oriented oxide particles. Hence it only works on the original 
    tape. Because it works via magnetism, it would be extremely 
    difficult, if not impossible, to implement skimming using 
    DSP." 

I've been loathe to test skimming because the effects of the
small erasure signal used to implement skimming on the signal
of the tape have not been well tested.  Because skimming can 
ONLY work on the original tape, you need to have sacrificial 
tapes with print-through to do these tests. I just don't know 
how "destructive" skimming is in an archival context.


Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx
http://www.TheAudioArchive.com
Disc and Tape Audio Transfer Services and Preservation Consulting


-----Original Message-----
From: Frances, Melodie [mailto:mfrances@xxxxxxx]
Sent: Tuesday, March 31, 2009 12:26 PM
To: EricJ@xxxxxxxxxxxxxxxxxxx; ARSCLIST@xxxxxxxxxxxx
Subject: Old reel to reel 'echo' problem


All,

I am not even sure 'echo' is the correct term, but with our old reel to
reel tapes (and I have had this experience with personal cassettes),
there is this thing I am calling echo - where what the person says is
repeated at a fairly low level - you can usually only really hear it
when there is silence - and it is basically a repeat of what had just
been said - so not really a echo but more like a delayed repetition. Is
this a head cleaning problem? Or a problem that can be fixed? Does
anyone even know what I'm talking about, and if so, what is it called?

Thanks


Melodie Morgan Frances
Head of Cataloging
Graduate Theological Union
mfrances@xxxxxxx
510-649-2521