While we're on the subject of squealing tapes....I'd like to hear some thoughts on dealing with deformed acetate backed tapes from the 1950s era.
The main culprits I'm currently dealing with are the Jensen and Irish brands. Main problems are curling and untrue running in the tape path. I've been using a cobbled up pressure pad assembly to maintain improved tape to head contact and all this has resulted in excessive wear and pitting of the tape head. (Hope to have a new half track head on the way from John French soon.)
I've had some success rehydrating thin acetate tapes in the past to soften and reform but find that the proper amount of moisture can be a fairly thin line to walk.
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Richard L. Hess
Sent: Wednesday, February 20, 2013 1:41 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Squealing Audio Cassette Tapes
The problem with this squealing is that it is often NOT accompanied by the massive buildups normally seen with Sticky Shed Syndrome. In fact, most of the cassette tapes that squeal do not leave any visible residue AND they do not respond to baking.
I am trying to more accurately describe phenomenon and also create an umbrella term to describe this family of problems.
Think of a BIG CIRCLE of a Venn Diagram and I'd like to call that Soft Binder Syndrome.
Then place a smaller circle fully within the big circle and call that Sticky Shed Syndrome.
Have you read my ARSC Journal Paper on tape degradation that was originally presented at the Audio Engineering Society's 121st convention in October 2006 in San Francisco was published in the ARSC Journal in the Fall of 2008? It is available here:
What we have seen is that the glass transition temperature has fallen to a point below room temperature, so the tape mag coat is rubbery instead of glass-like at room temperature (or slightly above as the heads often heat up a bit from heat generated within the player). We had one tape measured and its glass transition temperature was about 8 °C. We had another tape analyzed and it still retained its approximately normal lubricant load, so it is not loss of lubricant, but the fact that more lubricant is needed to make the tape play smoothly now that the glass transition temperature has become lower.
I have spoken to Karl on the phone and I think he will try cold playback and report back.
Using added lubricant works better for me on reels than on cassettes and cold playback works better for me on cassettes than reels. One reason for that is the reel machines I have throw off too much heat to be kept cool by the refrigerator I have. Also one reel machine's capstan froze at 4 °C.
It makes sense to me to have a little circle in the overall Venn Diagram that involves a symptom/treatment pair and, to me, Sticky Shed Syndrome is Massive Shedding, machine stopping, and ameliorated by baking.
This tag, Tape Aging, in my blog pretty well collects all the articles on the subject in order of most recent update.
On 2013-02-20 2:17 PM, Michael Biel wrote:
> The fact that the decks have stopped themselves on some of these makes
> it OBVIOUS that these tapes suffer from Sticky Shed Syndrome. If you
> continue to play these tapes while they squeal you will probably
> mechanically record the squeal onto the tape due to the actual
> movement of the oxide particles on the tape.
> And by the way, you are another of those on the list who have set your
> email program to have our replies sent to only you instead of the list.
> Please change this.
> Mike Biel [log in to unmask]
> -------- Original Message --------
> Subject: [ARSCLIST] Squealing Audio Cassette Tapes
> From: Karl Fitzke <[log in to unmask]>
> Date: Wed, February 20, 2013 1:20 pm
> To: [log in to unmask]
> Greetings, and thanks right away for your interest and potential help
> with the following:
> We have a set of approximately 30 SKC Brand, GX and LX model, Type I
> cassette tapes on hand to transfer. They are 60 minute tapes.
> The original field recordist is from New Zealand, where these tapes
> A number of the tapes start squealing after five to twenty minutes of
> play, and this happens on at least three different Nak CR-7A machines
> (dual capstan).
> The squeal is a rather constant tone in amplitude and frequency (2 kHz
> or so is a guess). The decks have even stopped themselves in some
> instances. The squealing in some instances has stopped when I stopped
> the deck, remove the cassette from it for inspection, replaced, and
> played again. But, only to likely start again a little later.
> Tapes have been fast forwarded and rewound before being played. I
> believe the squealing has happened when the tape is packed even
> better, e.g. after a play on one side (which didn't have noticeable issues).
> But play of the first side may not have been monitored very closely by
> personnel, so don't give that all too much weight.
> I've occasionally seen conical wrapping at the outside of the pack
> (the outside 1/8" or so, thinking radially).
> I've transferred some of these tapes to new Maxell shells, removed
> friction sheets in the original shells, removed pressure pads in the
> original shells, loosened case screws in both shells, threaded tape on
> the inside (instead of outside) of the posts near the cassette shell
> rollers in the Maxell shell.
> I checked W/F specs on all machines. They are okay, or just out of
> spec, which does not concern me here (yet).
> The best I've done is maybe reduced the amplitude and regularity of
> the squealing with playback of one tape I recall, but I haven't gotten
> rid of it.
> My current belief is that we have lubricant issues, and I'm off to
> read/reread everything I can find in old emails from Richard Hess,
> O'Connell, Steve Smolian that I saved for future reference, like the
> ones I've forwarded below.
> I'd be happy to hear anything else someone may have to offer. Even
> support! ;-D Thanks again for your interest.
> Best wishes,
> Karl F.
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
Quality tape transfers -- even from hard-to-play tapes.