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Author Topic: "Baking" old open-reel tapes  (Read 3167 times)

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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #30 on: December 17, 2020, 02:02:37 PM »
Yeah, it kind of made me want to avoid dealing with these tapes, knowing that they could fall apart like that. But I've got ~40 cartons of them, and they won't deal with themselves. So I've cautiously pressed onward.

The second reel that I baked, I left in the oven for 18 hours and it transferred very nicely. No shed, no sticky. One of the pieces on it actually sounded rather spectacular if I do say so myself: a Dolby "A" Nagra recording of a piece by a respected modern composer, for solo trombone and what sounds like about ten other wind instruments, recorded in what sounds like a church. (There were no markings on the box, just a label on the tape that said "G Lewis" with a Dolby symbol.) I was able to track down the composer (a trombonist himself and very likely the soloist), so that I can send him his tape after all these years, if he still wants it.

The thing is, I have no way of knowing whether that tape would have had problems if I hadn't baked it. So I'm still being cautious. I've got two tapes in the oven now, one of which has the slight, white dusting on it that indicates a problem, but the box says that it's a copy, so I'm feeling a little bolder. The other doesn't show any outward signs but it's a tape that was lent to me, so it may not be on Ampex stock, though it's at least similar-looking.

--best regards
music > microphones > a recorder of some sort

Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #31 on: December 17, 2020, 02:54:36 PM »
My general feeling is that if it's back coated tape from the 70s on up, especially Ampex, to just bake it. It's not worth the time IMO, to try playing such a tape beforehand to check the stickiness. It's 99.9% sure to have it, and I prefer to take the risks of baking first over the risks of playing first and scraping off oxide.

If its any consolation, I've only had 1 tape completely separate like that. I have had some tapes separate and transfer oxide to the adjoining layer in the last few inches around the hub, which usually has no or less important content. My theory is that there was more tape pack tension/compressing at the hub, and/or perhaps more baking would've helped. Based on the looseness a just baked tape pack has, I think an untreated tape pack must have swollen and is packed very tightly.

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #32 on: December 21, 2020, 07:53:43 PM »
> My general feeling is that if it's back coated tape from the 70s on up, especially Ampex, to just bake it.

That's what I decided, too. I wonder whether that first tape might have been saved if I hadn't rewound it first (sigh).

Meanwhile I've had three solid successes after baking the tapes for 18 hours. A little bit of white powder comes off while playing the tapes, but it sticks to the erase head and doesn't interfere with the transfer. Also, splices within recordings have held up so far, but with some splices between recorded tape and white leader tape, the splicing tape holds on to the recording tape but lets go of the leader tape, so I have to redo those.

--best regards
music > microphones > a recorder of some sort

Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #33 on: December 23, 2020, 12:55:57 PM »
I would ask Rich Hess if he thinks the complete peeling of coatings would've been fixed if not run first. I suspect not.

Splices are another matter. Generally, we have mostly Scotch white splicing tape and later on, some blue. I bake, then spool in library mode to check splices and general condition, and repack. If the splices seem to be holding, I go for a transfer, trying to listen carefully for audible anomalies especially at splices - sometimes they can slip a bit. Sometimes, the original splice is just at a bad spot (these are not commercial release recordings). Sometimes, the splice has left some goo on the adjacent layer of tape (usually at the edges), causing a stick-bobble during play. On these I use a dry soft cotton wipe to try to reduce the goo enough to play without damaging the oxide. Sometimes the splice just falls apart, in which case it has to be redone. I have been using a bit of Goo-Gone on a cloth to try to remove adhesive residue; put the tape end on a pad of paper, wipe longitudinally down toward the end of the tape, of course. I can usually remove most adhesive without taking off much, if any, back coat. Then re-do the splice. I try to take care since Ampex polyester will stretch rather than snap if deformed. Goo-Gone appears to be a lemon-scented oil type adhesive remover; alcohol would remove the coatings immediately. I have no clue whether Goo-Gone is doing other harm either short or long term, but consider these transfers to most likely be the last time these reels will ever be touched.

Sometimes I have to do a transfer 2-3 times if enough problems crop up, including just getting the levels wrong. It seems I can surf the web and still hear most, if not all, anomalies during a transfer!

Offline EmRR

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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #35 on: January 01, 2021, 10:35:55 AM »
I've run about 30 "baked" tapes now. Nearly all have transferred cleanly, with only occasional, minor powdery "stuff" (some white, some black) coming off the tape.

But two large reels of Ampex 406--both halves of a concert I'd recorded in January, 1980--have been the exception. My notes say that I had played them in 2008 without noticing problems. But yesterday they both put out significant amounts of sticky black gummy stuff when played. It cleans off easily with 91% isopropanol, though the density of discoloration on the Q-Tips is remarkable, and it seems particularly attracted to the capstan on my Revox. One reel had longer, continuous pieces than the other, so I couldn't readily stop every five minutes to clean; after a while, the substance coated the capstan to the point of producing audible flutter. (The music was a Mozart wind octet, so the flutter was more distracting than it would have been, say, with string music.) Fortunately my transfer from 2008 is adequate.

Since the one big disaster that I had (photos shown above), I'm wondering whether there will be problems with other tapes that undoubtedly had some precursor of the problems in 2008, but that I played then anyway without baking. Maybe I shouldn't try to re-transfer those now, even though I have a better A/D converter than I had then, and (since the tapes will be going to an archive) this is my last chance at them.
« Last Edit: January 01, 2021, 10:38:05 AM by DSatz »
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #36 on: January 01, 2021, 02:48:14 PM »
If really black, it would seem to be the backcoat. Maybe go for a longer bake time? Is the Revox worse than the Nagra?

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #37 on: January 02, 2021, 11:13:09 AM »
It does seem to be primarily a carbon suspension of some kind, and the oxide layer itself seemed OK on these two tapes. But I don't know that further baking (I'm already up to 18 hours) would help hold that stuff onto the backing. I think this is a rather different problem from the one that the baking process was designed to help with. Fortunately I'd made a decent transfer of those reels in 2008 (or unfortunately, if by doing so I caused this problem to occur now), but in any case I decided to go on to find, or create, other problems.

I say "create" because yesterday I inadvertently mishandled a reel that was off of its flanges, and in trying to get it back together, made it worse, creating the worst tape salad that I've ever had in my life. It's tempting to treat it as New Year's confetti--but since time has no meaning these days, I will spend at least a few hours today trying to reclaim the tape. It could be another one that I transferred in 2008--I have to play it to make sure; its exact contents are unidentified--but maybe it's not.

--best regards for 2021
music > microphones > a recorder of some sort

Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #38 on: January 02, 2021, 12:40:55 PM »
Sorry about the salad. It might be theraputic to watch a movie while putting the tape back on a spool.

I am hearing more people say to bake at least 24 hours, even 48 hours. My feeling is that if it's black, it's backcoat and inconsequential if some scrapes off, assuming it doesn't interfere with playback mechanics.

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #39 on: January 11, 2021, 09:53:30 AM »
I need to find white cotton gloves to wear when straightening out the tape. Even with my glittering New York social life nowadays, my valet tells me that I don't have a pair of those in my dresser drawer. This is dreadful; whatever shall I wear now with my tuxedo and top hat, monocle and white-tipped cane? I must dispatch my butler to the haberdashery post-haste.

--The tapes are almost all in good mechanical condition after baking, but the ones that were recorded without noise reduction sometimes have levels of print-through that will limit their usefulness, other than as mementos. Even Dolby "B" makes enough difference to matter there. I'm being more critical than some other people probably would be, plus I'm mostly listening over headphones, but it's still sad. OTOH the ones recorded with better noise reduction systems, such as Dolby "A" or telcom c4, still sound awfully good if I do say so myself, depending on the miking and the performance.
« Last Edit: January 11, 2021, 10:10:39 AM by DSatz »
music > microphones > a recorder of some sort

Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #40 on: January 11, 2021, 11:45:06 AM »
I've been transferring a lot of 30ish year old cassettes lately, and it's the first time I've really noticed print-through in that format.  Dolby doesn't seem to make much difference here.   I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate. 
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline morst

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Re: "Baking" old open-reel tapes
« Reply #41 on: January 11, 2021, 04:33:24 PM »
I've been transferring a lot of 30ish year old cassettes lately, and it's the first time I've really noticed print-through in that format.  Dolby doesn't seem to make much difference here.   I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate.
I did a bunch of transfers in approx 2009 using incorrect DBX type I modules for cassettes recorded with DBX (Type II is correct for cassettes)

Since then, I did a little looking and gearsluts, I think it was, indicated that the DBX 224X-DS is the highest quality DBX Type II converter.
So I bought one.
They come up on ebay, usually in the range of $100-300. Hint, I paid more like $100, delivered.
Have not used it yet, but it lights up. Gotta get to my storage unit and get a box of DBX masters, and then get a deck I trust, that's worth passing the tape across the heads!

Ah maybe it was tape heads
https://www.tapeheads.net/showthread.php?t=4801


random example (band changed their name last year due to social issues)
https://archive.org/details/dixie1991-10-16-flac16/
« Last Edit: January 11, 2021, 04:35:49 PM by morst »
Merrick Garland *was* a compromise, and just look.

Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #42 on: January 11, 2021, 04:54:46 PM »
I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate.
I did a bunch of transfers in approx 2009 using incorrect DBX type I modules for cassettes recorded with DBX (Type II is correct for cassettes)

Since then, I did a little looking and gearsluts, I think it was, indicated that the DBX 224X-DS is the highest quality DBX Type II converter.

Cool.    Good to know the 224X-DS is considered best, I couldn't make out any real differences in a first look. 

My type I are 411 cards in a 900 rack along with other dbx cards, so I'm looking for a 942 card or two first, but that might prove more expensive.  There's also the 408 card, but I'd need 2-4 of those. 
« Last Edit: January 11, 2021, 04:58:06 PM by EmRR »
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
Recorders: Zoom F8n, Sony MZ-R50, portable MOTU based multitrack DAW for client work

Offline morst

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Re: "Baking" old open-reel tapes
« Reply #43 on: January 12, 2021, 09:09:47 PM »
Back in 2009, I used the DBX150 which is a single-rack-space unit, not really a module.
(photo from ebay)
Merrick Garland *was* a compromise, and just look.

Offline 108Ω

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Re: "Baking" old open-reel tapes
« Reply #44 on: January 15, 2021, 04:44:25 PM »
On tape-baking:
I've always wondered that if stored in super-low humidity for, perhaps, two weeks, would the moisture expel more safely than with heat ?
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