Re: [ARSCLIST] TAPE resources online

[Matt Sohn <mahatma57@xxxxxxxxxxxxx>]

Parker Dinkins wrote:
> I think contact with a smoother surface might cause this, and not
> necessarily because it's another record-layer. I've seen the record-layer
> binder come completely off on the smooth hub of the reel, and especially 
> on
> early 3M plastic leader tape, which is relatively shiny and smooth. Then
> when the wrap is against the back-coat, everything stays in place.

I have had this problem as well, only once with the hub, but more often with 
the 3M plastic leader. I asked about how to deal with it during the "Ask the 
Technical Comittee" session at the last ARSC conference, and the only answer 
I got was to "unwind the tape very carefully". In my experience, the leader 
tape problem seems to occur with 3M plastic leader used between late 1977 
and early 1978, and seems to be confined to Ampex 406-407 and 456-457. In 
the current project I am working on I see it on virtually every one of the 
tapes from that period from those tape stocks. Tapes from early 1976 and 
late 1978 are not affected, and in the few cases where yellow leader is used 
on 1977 tapes, the problem does not occur. There are a few reels of Maxell 
tape from the same time period that don't have the same problem (and don't 
require baking either). Since these tapes are sticky-shed and stored 
tails-out, I was baking them before rewinding, and when rewinding, the wrap 
where the oxide contacted the leader would lose chunks of oxide (blocking, I 
belive it is called), which was adhered to the leader. Once I realized that 
it was not a one-time occurence, I would rewind until just before the 
leader, stop the machine, and very carefully peel the final wrap off the 
leader, but I still got oxide coming off on the leader (not blocking, but 
traces). Some of the tapes had leader between every song, and I noticed that 
it got worse as I got closer to the hub. The layers nearer to the outside 
would unwind fine, but the closer to the hub, the worse it got 
(tension-related?). The problem seems to be exacerbated by baking. A few 
tapes that were stored heads-out did not exhibit any problems, but the wraps 
of leader would be sticking to themselves as they unwound.
I tried an experiment, where I rewound a reel (bypassing the tape path) 
before baking it, and had no problems playing it. The oxide did not adhere 
to the leader when rewinding, but after baking, the wraps of leader were 
sticking to each other. Since then, I have chosen the lesser of two evils 
and rewind tapes (bypassing the tape path) before baking when I have leader 
present. I suspect a bad batch of leader, combined with SSS.
One other thing. For the tapes with chunks of oxide stuck to the leader, I 
was able to minmize the dropouts by the following process:
I cut the tape from the leader, flip it over and re-splice it at both ends, 
then record the tape. Then, using the Audio Montage in Wavelab, I copy and 
paste the affected portion of the track into one stereo track of the 
montage. Then I copy the portion of the leader containing audio signal, open 
it up in it's own window (as a new audio file), reverse the channels and 
phase-invert them. then I place that audio into another stereo track in the 
Montage, very carefully line up the waveforms on the timeline, and render a 
new file from that. Then I render the Montage as a new audio file and paste 
it back into the original file, replacing the affected portion of audio. 
It's time-consuming and a pain in the tucchus, but I have gotten very good 
results using this method, and the more cleany the oxide has adhered to the 
leader, the better the results have been. Unfortunately this method won't 
work when the oxide is stuck to the hub..

-Matt Sohn