Squeaky cassettes
MusicConductor:
Occasionally the odd cassette turns up for which there is no CD or LP version, or at least not conveniently. So a careful capture in AA3, gentle de-hissing applied, burn to CD, and there you have it. Right?
Just now listening to the beginning of the last one I did before the busy holiday season. Not good. My work was fine, but the tape is not happy, and it's not the first time I've run into this problem. Transfer stopped midway and abandoned.
A Google check confirms I'm not alone: cassettes manufactured for the EMI classical label (and probably any EMI) lose their ability to play over time, as though the oxide turns to a mild adhesive. At first the playback will start to droop in speed as friction builds, and eventually the tape squeaks across the tape path quite audibly. Both are ruinous to a successful transfer, obviously. Unlike typical sticky-oxide syndrome, these tapes have no back coating and also don't tend to deposit layers of crud inside the machine while squeaking.
I've tried changing the tape to a different, high quality shell; baking it; lightly appliying silicone; and drowning it in silicone (tape now ruined). All of these have NO affect on the problem.
I'm wondering if any of you have knowledge of the problem, specifically what is changing over time in the chemical composition of the oxide, and if there is any antidote.
SteveG:
Quote from: MusicConductor on January 19, 2011, 06:46:28 PM
I'm wondering if any of you have knowledge of the problem, specifically what is changing over time in the chemical composition of the oxide, and if there is any antidote.
I'm aware of the problem, and it's not just limited to EMI tapes. As far as I know it's caused by the lubricant on the slip sheets that prevent the tape making contact with the cassette itself. The lubricant sort-of mingles with the tape, and becomes a part of it - and not a lubricant any more. Unfortunately what I don't know is whether there's any cure. It's been suggested that the one thing you shouldn't do is to bake them - that is apparently likely to make things worse, not better. The squeaking seems to be related to whatever the oxide coating has become being forced into contact with the playback head, presumably by the pressure pad.
As a result of this, the one sensible thing I've heard that's been suggested is to try to play the tapes on a dual-capstan 3-head Nakamichi, some models of which incorporate a small lifter for the pressure pad, and rely on the dual capstan drive to keep the tape in contact with the heads. This is apparently a lot easier on the tape, and assuming that it will actually come off the pancakes without destroying itself, may be a way forward - if you can find/requisition/borrow/whatever a Nak... (My LX-5 doesn't have the lifter, but it certainly uses the capstans to control the head pressure, so it plays cassettes without any pressure pads at all without problems. I think that it's the really expensive Naks that have the lifters, and one of those hasn't come my way yet.)
Experiments have been made with attempting to re-lubricate the tapes, but I'm not aware of any successes. Silicone apparently won't cure the problem at all, although it has been suggested that a wipe with alcohol will at least temporarily ease the problem - but this is really hard to do with a cassette unless you can get it out of the shell. If you can, run it through a pad soaked with Isopropanol, and things might well improve for a while. Other than these, I have no immediate idea of what else to try, though.
pwhodges:
Maybe this ties in with two tapes manufactured in 1991 that I recently acquired, both of which broke when I attempted to play them (in a two-capstan Akai). On breaking the shells open with a view to splicing them, I found that successive turns were in places stuck at one edge, which would match the idea that the slip sheet was the source of the trouble. Mind you, there were also signs that their storage conditions had been poor at some time. Fortunately (because they are very rare) I have since been able to track down CD copies of both releases.
Paul
AndyH:
I can't say that it isn't a totally different problem with the same, or similar, symptoms, but I’ve made major improvements in a number of squealing cassettes by taking the slip sheets out.
Bert:
One simple thing is to use a tape deck with the cassette sides running horizontal. Try to rewind the tape several times backward and forward. This helps to bring the tape stack to the lower side. If it plays so - OK. If not, reverse the tape and repeat the same. Then the stack goes to the other side - may be succesful this time. However I agree this to be a matter of desperance.
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