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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 17th Aug 2017, 11:21 am   #1
toshiba tony
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Default Tape screeching

Well, this ones got me. I have a Philips N4506 that has suddenly developed a screech whilst the tape is running. Only on certain tapes. The back tension is ok, it appears to be coming from the erase head. It really is objectionable. It sounds just like someone is running their fingers down a blackboard. This is an accurate description. There is no visible evidence of wear on any of the heads, (erase\record or playback) There is small selector on these machines that you change if you are using the shiny side of the tape to the heads, and moving this to the wrong position greatly alters the screech, can tapes wear in such a way that would cause this? I am not conversant with tape formulation. Thank you.
Tony Walker
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Old 17th Aug 2017, 11:39 am   #2
Andrew2
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Default Re: Tape screeching

Sounds like 'sticky shed', a well-known problem that has caught-out the broadcasting industry and hobbyists alike. It affects certain brands of videotape as well, and a whole industry has built up around the rescue of valuable tapes thus affected. After many years of storage, some tapes degrade and release the binder that holds the oxide to the base. This causes the screech as the tape 'twangs' across the guides and heads. It can also deposit a hard, sticky mess on the heads & guides that can be a devil of a job to remove. I managed to salvage some of my old tapes by fast forwarding the tape against a cotton wool pad moistened with isopropyl. I also thoroughly cleaned everything in the tape path. This made the tapes playable for long enough to transfer then to MP3 format.
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Old 17th Aug 2017, 12:02 pm   #3
toshiba tony
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Default Re: Tape screeching

Andy, so I have sticky shed, have I? I've heard of it but never been a victim. You may well be right, the worst offenders are Agfa tapes, I read previously one type of Agfa is a bad one. I regularly clean the tape paths on all my gear so I will watch for deposits. Luckily, any valuable recordings don't present problems, these Agfa's were recently bought on E-bay, the seller. I'm sure, was honest. The tapes were full of Radio 4 plays!
But I reckon you have cracked it for me. Thank you.
Tony Walker.
MP3, Not keen on that, won't have cd either or DAB. But then again I believe FM is compressed now. Getting fussy in my old age, cheers.
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Old 18th Aug 2017, 8:46 am   #4
Chindit
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Default Re: Tape screeching

FM compression? I wouldn't be surprised, as the powers that be wouldn't want FM showing up nice shiny DAB!
Tony, I had something similar occur with one of my N4506 recorders. Can't remember what make of tape was causing the screech but it was a pre-recorded music tape I bought on eBay. Haven't had chance to investigate further as I've recently moved house. I agree, it DID sound dreadful though!

Colin.
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Old 18th Aug 2017, 8:54 am   #5
lesmw0sec
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Default Re: Tape screeching

I have this problem when playing certain old tapes on my A77. The only remedy I have found is to fast wind the tape from end to end while lightly squeezing it in a soft cloth before play. The worst offender being some 'professional' matt-backed stuff. The one which rarely gives any trouble is EMI 815.
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Old 18th Aug 2017, 9:08 am   #6
Ted Kendall
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Default Re: Tape screeching

The usual treatment for binder breakdown on these tapes is baking. The conventional wisdom is 55 centigrade for eight hours, although typical baking times have increased gradually. Above 60 centigrade tends to exacerbate print-through, and below 50 has practically no effect. The fix lasts long enough to get the information off the tape - typically weeks or months.

As discussed in another thread, practically all FM is processed these days. To be fair, it always was to some extent - dynamic range was always manually compressed by gain-riding in the studio, and pre-emphasis limiting was on transmitters virtually from the start of national stereo services. The rot set in with Optimod, in my view. As with any effective treatment, over-use is harmful, and Optimod is generally over-used. Mind you, I find some of the Radio 3 balances a bit odd these days...
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Old 20th Aug 2017, 5:40 pm   #7
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Default Re: Tape screeching

Agfa, BASF & New Old Stock Philips cassettes I have suffer the same fault, for the same reason as advised.
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Old 20th Aug 2017, 6:07 pm   #8
G6Tanuki
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Default Re: Tape screeching

I've had similar issues with various cassettes where the pressure-pad on the rear-side of the tape has suffered ageing and has started dragging on the tape.

Treat this as a prescient warning: do all you can to grab the content [even if it means a sacrificial single-pass of the magnetic media] and then archive it digitally.

Magnetic Tapes will never get better with age. Digital at least allows you to freeze the degradation.
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