RE: arsclist VHS and S-VHS Tapes

["Copeland, Peter" <Peter.Copeland@xxxxx>]

Dear All,
    This discussion is becoming somewhat prolonged, largely my fault I'm
afraid.
    Mike Richter raised the very real point that the audio Hi-Fi tracks use
reciprocal noise reduction. (I insert that word "reciprocal", because when
everything works well, you get back the original undistorted sound, as
opposed to other noise-reduction processes which *aren't* reciprocal, such
as the second and third stages of "The Packburn", or the Philips DNL ( =
Dynamic Noise Limiter)). When the carrier-levels of the hi-fi tracks aren't
very strong, the dBx-type expander can emit added noise from the
head-switching circuitry (or from a poor playback head, or one slightly
off-track), which it cannot hide. This is because the video is recorded
using analogue FM (frequency modulation) principles, like a local radio
station. Conventional hocus-pocus suggests that FM radio is only noise-free
so long as the carrier-level is about double any interfering noise. That is
the main argument in favour of using S-VHS tape for preservation purposes;
when something isn't right, you've got about double the carrier strength to
play with.
    A second consideration (as you may guess from the last paragraph of my
original posting) is that we're often handling music broadcasts. The
dBx-type noise-reduction is always upset in the presence of unwanted sounds
outside the audio frequency-range. In Europe, broadcasters generally (but
not always) bandwidth-limit their transmissions to prevent such
side-effects. As an anecdote to explain my meaning more clearly, the worst
hi-fi track I have had to deal with was of a Wagner opera from the Royal
Opera House here in London. Normally, Wagner's music will drown anything;
but there was a moment where a solo soprano was singing softly and without
orchestral accompaniment, lamenting the death of her lover. The combination
of the out-of-band noise from the Royal Opera House's air-conditioning, the
quietness of the wanted sound (very close to the head-switching noise on the
hi-fi track), and the vibrato, meant it was very difficult to get the sound
clear of the noise. It's some years ago now; but I believe we had to buy a
new machine with new heads and perfect mechanical alignment to cover the
noise!
    But, had it been on S-VHS tape, there wouldn't have been a problem.
    With regard to Brian Levy's note below, I would only back up CD-Rs using
digital methods, and I would only use VHS or S-VHS if you have enough Sony
PCM-F1 processors (or equivalents) to get you through the next fifty years
or so. I believe *we* have. You would also need something called a PCM-601
to convert from SP-DIF into the digitised-audio video domain. We've only got
one; if anyone would like to sell me another, I'm open to offers! 
Peter Copeland 

-----Original Message-----
From: Brian Levy [mailto:xernaut@xxxxxxxxx]
Sent: 28 February 2002 06:40
To: ARSCLIST@xxxxxxxxxxxxxxxx
Subject: Re: arsclist VHS and S-VHS Tapes


Dear Peter,

What about the possibility, as suggested to me by someone working at one of 
the places I purchase  blank CD-R media for our Indian language 
preservation projects here in Oklahoma, of using S-VHS to store analog 
back-ups to all our CD-R's in our archive, just in case the digital 
strategy fails?  Since quarter inch reel is expensive, especially for a 
smaller archive with little funding, like ours, might'nt this be a smart 
choice?

                Thanks for your posting,

                           Brian Levy

At 06:40 PM 2/27/2002 +0000, you wrote:
>Dear All,
>     My apologies for being late entering this discussion, I was on "summer
>holiday" (last week and the week before!). I should like to contribute
>something from the *audio* point of view.
>     For the purposes of long-term preservation of the audio accompanying
>both VHS and S-VHS tapes, we "clone" onto blank S-VHS tapes.

--------------------------------------------
Robert Brian Levy
Executive Director
Kiwat Hasinay Foundation
P.O. Box 305
Binger, OK 73009 USA
1-580-515-6011
kiwat@xxxxxxxxxxx
http://www.ahalenia.com/kiwat



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