Re: [ARSCLIST] MAGNA-REEL Sound Recording Tape

[Dave Nolan <davenolanaudio@xxxxxxxxxxxxx>]

Hello all - 

May I say a huge THANKS! to everyone who has helped to answer my question
(s) about these tapes from 1950-51...

To clarify a couple of things:

>Is there a strong smell of vinegar or "lemon chicken" with these tapes?

Yes.  The squealing tapes definitely have that "lemon chicken" smell.

>So, the easiest thing to do is to see if it's a Tg issue. Place the
>player and the tape in a cold space (aka refrigerator) for a few
>hours until everything comes to equilibrium. Hit play. Does it still 
squeal?

Is there a recommended length of time in the fridge that anyone on the list 
has used successfully?  Any other "tape-in-the-fridge" handling tips?  Any 
suggested ways to measure whether the tape has hit 4 degrees celsius?

>Adding moisture will generally make the tape softer and will increase
>squeal, so rehydration would not be recommended at this point.

Is rehydration still acceptable for non-squealing acetate tapes that 
exhibit signs of cupping, excessive brittleness, etc...?  I haven't gotten 
to those yet, but will soon...

>The other option is to reduce tensions and do a Pellon wipe (or
>several) as that has worked on 3M 175 (again a later tape).

While we're on the Pellon subject - 

A)  Is there a specific type of Pellon that is recommended for this sort of 
use?  I was very surprised to see the many many types and finishes of 
Pellon out there - smooth, furry, thin, thick, etc...  And of course, any 
Pellon-handling tips and tricks would be greatly appreciated.  I recently 
saw an engineer using a 2" square between his fingers to clean the surface 
while library-winding a tape.  Other folks have suggested creating a Pellon 
pad that entirely covers the stationary parts of the head block and either 
playing back in "real-time" or library winding.  What methods do folks here 
like and why? 

>The squeal MUST be attended to during playback as it is a stick-slip
>condition and will print to the digital file (as you discovered). So
>you don't even need to test with audio. If you can hear the squeal,
>try something else.

There is one technique I have heard discussed where one can theoretically 
rig up the reel-to-reel machine to have the tape touch NO stationary parts, 
but to have the tape pass close enough to the playback head for the signal 
to be properly transferred.  Is this reality or science-fiction?

>One other thing to consider about lubricant. It's there based on the
>design friction load. As the Tg drops, the tape gets more rubbery and
>the real tape contact area increases. Normal tape has a contact area
>in the neighbourhood of a few percent (2-3%) of the entire surface
>area, and the normal lubricant loads are designed for this with some
>margin. If by softening the surface, the contact area goes up, there
>isn't enough lubricant. This is why Marie O'Connell's wet playing
>works, but I'm not sure I'd want to try that with acetate as acetate
>is far more hygroscopic than PET (which is, surprisingly somewhat
>hygroscopic).

I have been in touch with Marie - as well as some other folks here in NYC 
that are successfully using an isopropyl system to play back LOL tapes.  My 
only question is:  Has anyone had any long-term deliterious effects from 
the isopropyl on the tape?  I'm not a scientist, nor do I pretend to be 
one - but based on my limited use of isoprpyl to clean built-up oxide off 
of tape heads, I'm wondering what effect (if any) on tape from using the 
alcohol method might have been observed by list members... 

>I hope shortly after AES to be set up to do cold playing easily, but
>I'm swamped at the moment. I really would like to know your results.

I'll certainly give everyone's suggestions a try here - and thanks again to 
Richard in particular for the in-depth response...

dave nolan
92nd St. Y
nyc