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ARSCLIST  July 2008

ARSCLIST July 2008

Subject:

Re: Wire players

From:

Jim Lindner <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Sat, 26 Jul 2008 09:42:28 -0400

Content-Type:

text/plain

Parts/Attachments:

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text/plain (233 lines)

Ah..... summer in North America.... short replies take a while - long
replies take a long time - this is a long reply but I think the time
has come to at least partially document efforts made by myself and Art
Shifrin at my old company VidiPax more then 10 years ago. The lessons
learned will likely be helpful to many on this list now, and perhaps
more importantly to those who ponder these type of issues in general
in the future - so I am counting on the Internet to index this somehow
so someone who may have a need in the future can find it.

Based on a great deal of experience over time, I developed the theory
that magnetic recorders (and frequently other media types as well)
were in fact capable of far higher quality recordings then they were
able to play back on the same machine. I slowly developed this theory
during a period of about 5 years when I first started to do format
migration work and was dealing with some very difficult issues in the
video area - specifically relating to signal timing and playback which
is of course critical in video. I noticed that while the machines
could always record a signal - whether the machine could play back
that signal (or another signal due to interchange issues) was an
entirely different matter. This theory has proven to be correct over
the years in many instances. Even if a machine was out of alignment it
WOULD record in an out of alignment way - the trick then was to figure
out how to play back that signal - and it was far more difficult in
many instances to play back that signal with the electronics of that
era.

When one thinks about that now - it may be no great epiphany - but it
was to me at that time because it made me realize that in fact
virtually millions of recordings have NEVER been heard or seen with
the same fidelity as had been recorded, and this occurred to me with a
sort of overwhelming realization at that time. That meant that one
COULD develop ways to play back recordings with modern electronics
(modern by definition does not necessarily mean today "state fo the
art" but could mean more modern relative to the time the technology of
the recording was made - and sometimes in a "golden era" of
electronics when certain gear that did particularly well with certain
signal types was available).

When testing this theory with video, I found that it was sometimes
true and sometimes not depending on a number of factors - but
primarily one factor specifically in video that the electronics for a
period got more tolerant (and therefore able to indeed play back
better then the original recorder could) and then less tolerant - as
state of the art came to mean that all electronic timings were perfect
from first recording and so the playback electronics really did not
have to be very tolerant at all (in the analog domain) because all of
the recorded signals were in good shape (if nothing went wrong). So
when a tape that was in crapola shape came for playback 30 years
later, playback was exceedingly difficult because the electronics of
that vintage expected everything to be perfect, there was no tolerance
to speak of, and so it was a nightmare project to get a decent
playback. This is still the case with it being far more difficult to
play back a severely damaged digital recording then an analog one.

During this time Art Shifrin came to work for me at my company at that
time - VidiPax. We were at the time business colleagues and friends
(and that unfortunately is no longer the case). At that time we
discussed this theory I had - which made sense to him. The business at
that time involved playing back obsolete formats and Wire Recording
playback was a format we supported. We used period wire recorders, but
you did not need to be too good of an audio engineer to see that the
playback electronics on those machines (either professional or
consumer) was pretty awful. The transports were largely Rube Goldberg
affairs if you look inside of one - and we both figured there had to
be a better way. We decided to find out if my theory was true for Wire
Recordings - even considering their age and low coercivity - and
decided to build ourselves a test bed device to see what might be
possible. Now remember that this was for internal purposes only for
our playback business - there was never any intention to actually sell
one of these.

In earlier days Art worked for Ampex as a repair technician and knew
the insides of the reel to reel decks cold. The Ampex decks were also
in plentiful supply essentially for the asking, and both of us had
very high regard for the quality of the Ampex playback electronics
having a clean sound that was analog and appropriate for the playback
of the wires - at least conceptually. There were many other questions
however - such as heads.... Would standard playback heads playback the
low level recordings from the wire? We did not know, but I reasoned
that the worse case would be that the levels would be low and that the
S/N would then be in the dumps - but we could deal with that through
preamplification tweaking or through getting a custom head stack and
preamp made if necessary (we of course had wire recorder heads and
there are several expert head rebuilders around and could easily
commission a new head with different characteristics and
electronicsbased on the output level from the wire). We reasoned that
worst case it would be no lower then the output from a turntable
cartridge and we could easily deal with that if we needed to. We found
to our delight that we did not have to go to these extremes, but that
a standard full track head worked just fine with the standard
electronics with just a few tweaks, provided that we could hold the
wire in place (the moving of the wire across the head made all sorts
of sonic problems as you might imagine). Art devised a very simple
design whereby he glued tiny wedges directly to the head to hold the
wire in precisely the same position. Think of tiny triangles placed
against one another with the bare head inbetween. The wire was
"encouraged" to stay in place by the tension place upon it - and it
rode in the groove between the two triangle wedges. As you might
imagine the wire had higher friction then a tape would, so we wore the
heads down a bit faster - but we had plenty of cheap Ampex full track
heads, plenty of super glue, and plenty of plastic wedges so it was
not much of a problem.

We also decided immediately that the transport system should be
capstan driven. Provided that the wire could be maintained at proper
tension through the entire playback path we believed that we could get
a much more consistent playback then period machines were capable of.
This was found to be true. Art did a great job on the transport system
spending a huge amount of hours and eventually we enlisted the
services of a friend of his that had a small machine shop, and built
some components to essentially do 2 things - one was to allow the
capstan to move the wire consistently at speed, and the other was to
move the wire at the take up position so that it was not deposited in
one place. To do that we essentially took the idea from a deep sea
fishing reel and had a bobbin type assembly that moved the wire
forward and back as the reel turned automatically. This was a tricky
bit but with some experimentation was shown to be more reliable in
terms of constant speed over the head then moving the reel up and down
(as is done in some commercial wire recorders).

Bottom line - it worked and the results truly amazed both of us. The
theory was more then correct and the results really were amazing - we
had expected better but what we got was so far better that we truly
were astounded. There was no more sound that sounded like you were
listening through a cereal box - the sound was almost always clear and
with really decent frequency response.

Art left the company and I believe continued work on his own on the
device. Art deserved Kudos for doing the work that he did, and
continuing on his own. I have always referred this type of work when
it showed up to him in ensuing years whether he realized it or not.
There are no "plans" and there were no other machines that were built.
I am absolutely positively convinced that if you want to really hear
what a wire recording has recorded on it - this approach is the one to
be followed. It will take some time and money to do - but you now have
the advance knowledge that we did not have - that in fact it DOES work
and is worth the effort. Try it - you too will be amazed. The recipe -
several used Ampex decks - used but not abused. Access to a machine
shop to make a few parts. A good understanding of electronics and the
schematics to make a few tweaks that you will find you need, good
mechanical ability, lots of coffee, and a great deal of time to fiddle
with it. It will be worth your while.



Jim Lindner

Email: [log in to unmask]

   Media Matters LLC.
   SAMMA Systems Inc.
   450 West 31st Street 4th Floor
   New York, N.Y. 10001

eFax (646) 349-4475
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www.media-matters.net
Media Matters LLC. is a technical consultancy specializing in archival
audio and video material. We provide advice and analysis, to media
archives that apply the beneficial advances in technology to
collection management.

www.sammasystems.com
SAMMA Systems provides tools and products that implement and optimize
the advances in modern technology with established media preservation
and access practices.



On Jul 18, 2008, at 11:11 AM, Prentice, Will wrote:

> We're trying to decide whether to rebuild an old wire player (or
> two) or
> start from scratch. Our maintenance engineer asks:
>
> "We have a small number of wire recordings in our collections, in a
> variety of formats. We'd be interested to know what solutions other
> archives have found for playing back wires. I know that there are old
> machines still available, and some commercial operators using them to
> make transfers, but have any of you built or commissioned new
> machines,
> and how have you found the process? How do you handle different
> formats
> - is it a good idea to have a separate machine for each format, or is
> one 'universal' machine possible? Are there outfits or operators
> around
> selling new machines and what would be the likely costs?"
>
> All informed thoughts welcomed.
>
> Regards
>
> Will
>
> ..............................................
> Will Prentice
> Technical Services
> British Library Sound Archive Tel: +44 (0)20-7412-7443
> 96 Euston Road Fax: +44 (0)20-7412-7416
> London NW1 2DB http://www.bl.uk
> UK http://cadensa.bl.uk
> (online
> catalogue)
>
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