Topic: Strange cassette issue during A>D

[NewHomebrew]

I'm digitizing a 30 year old C120 cassette, a BASF LH super, and the strangest thing is happening on playback.  Press play, the tape sounds fine.  30 seconds later the levels taper off and the sound becomes muffled and crackly.  Stop the tape, press play again, and the tape sounds fine, but then gradually decays.  What's going on here?  Based on where I start playing back the tape, a certain portion may sound fine or may sound muffled.

I've tried different cassette decks and transplanted the reels to a fresh, premium shell.  The problem persists.

[rowjimmytour]

I remember reading about the Dead havin' to bake the reel to reel SDB's before the A>D transfer and after bakin' they had one chance to play and thats it. There was a article about this in one of the volumes of the taping compendium by John Dwork.
Peace

[NewHomebrew]

I hope I don't have to bake it.

Here's a sound sample of what's happening.  The sound deteriorates until it's completely muffled at around 20 seconds, I stop the tape, press play again, and it comes right back to normal.

http://s4.yousendit.com/d.aspx?id=0PW6MOPRE9MW00PXBF26OFJ4TH

Do you bake the cassette spools inside the shell?

[rowjimmytour]

I am not sure of the complete process mabey some one else can help out. Bakin' tapes is suppose to make them playable when the glue on the back of the tape gets old and starts to come apart I believe. Good Luck
Peace

[sml42]

Mmm, vintage Roy

As I understand the 'baking' process... with certain older tapes, the glue used to stick the magnetic particles to the tape would, even when stored in ideal conditions, degrade. It would become 'sticky' with the result, when you ran the tape past the heads, you would get a goopy mess and ruined tape. By baking, you dry out the glue, when the tape runs past the heads it pretty much disintegrates but at least does not goop up, so you have a (single!) chance to extract audio.

If your tape heads are not gooped-up and the tape itself looks intact after playing, chances are you don't need to bake.

What deck are you using to play this back? The same 30-year old deck it was recorded with? (in which case the deck may be in need of renovation). A new deck? Can you play other (i.e. newly recorded) tapes correctly?

The muffled sound would tend to indicate a head misalignment / azimuth issue. Can you tweak the azimuth on the playback deck? Still doesn't explain why it starts clean then becomes muffled... hmmm.

best regards,
stephen

[heath]

By baking, you dry out the glue, when the tape runs past the heads it pretty much disintegrates but at least does not goop up, so you have a (single!) chance to extract audio.

Not necessarily correct.  After baking, you have almost zero residue left on the heads during playback.  The tape will not be harmed during playback (unless it's in REAL bad shape--but usually not Sticky Shed Syndrome) and can be played numerous times. 

I'll post a link to a thread in which I described baking and even posted some pics of SSS. 

You could be leaving residue on your heads from deterioration that is different from Sticky Shed.  Usually a white powder residue that is hard to see until it accumulates quite a bit.  Baking might help (you could do this inside the cartridge, but it's probably better to remove from the shell), but the best process would be a thorough cleaning of both the tape and your heads (manual--not a cleaning tape). 

Also make sure to chek playback head alignment.

I'm in a bit of a rush as I have tapes piling up on my desk as I type, so I hope this made a tiny bit of sense.   

[heath]

here is some info i posted in another thread:

http://taperssection.com/index.php?topic=36765.msg470467#msg470467


and some pics of SSS on a studer 24 track headblock:

http://taperssection.com/index.php?topic=36765.msg483601#msg483601

[sml42]

here is some info i posted in another thread:

There you go. I was regurgitating what I remembered from reading magazine articles. Thanks for setting me straight, +t

best regards,
stephen

[NewHomebrew]

Thanks for the replies, I appreciate it.  The deck is a Nak 600 that is well kept.  No problems with other tapes at all.  I cleaned the heads and everything else - the swabs didn't pick up much gunk, just a little bit of crud.  They certainly don't look caked in residue.  The tape looks fine as well.  Maybe the heavy spools of the C120 are drifting as the tape plays and tension changes?  I'll bake the tape as a last resort.  Would it be best to have each spool with half the tape or all of it on one spool?