Tape Project Forum
General Category => General Discussion => Topic started by: TomR on March 20, 2009, 10:00:41 AM
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I have way too many prerecorded tapes that I bought in the 70's that squeal when I play them (or try to play them - the squealing is unbearable). These include some that I consider to be real gems - the San Francisco Opera Gala (an operatic greatest hits, sung by Decca's greatest stars of the 50's and 60"s), the Barber of Seville with Varviso conducting, Mahler's 2nd with Solti, and most likely others - I have been too nervous to try to play some of my tapes. All of these are Ampex sourced tapes made in the 70's, although I also had a BC tape squeal slightly (the Stokowski led Rach 3).
Based on a discussion that we had last Saturday at Astrotoy's, I purchased a small bottle of LAST tape preservative and last night tried it on my first tape, which was the Solti Mahler 2. BTW, while I understand that one can buy LAST products from various sources, I bought mine factory direct - ordered it on Monday, had it in my hands on Wednesday. Great email follow up and great service.
LAST tape preservative is easy to apply, and a lot less wet than I figuredd it would be. I treated the reel both on fast forward and rewind - the instructions indicate you only need to do it once.
So - I was definitely encouraged when the tape did not squeal at all on side 1. However, halfway through side 2, it started to squeal again, which was very disappointing.
I am planning to re-treat the reel and try again, and I will also try it on a few other tapes - nothing to lose, correct?
Question for those of you that have tried this - do you also use the LAST head treatment in conjunction with the tape preservative?
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Hi Tom, if the Ampex tapes that squeal are backcoated, it's probably sticky shed. It's not the backcoating but the era of tape manufacture as far as anyone can tell at this point (there is some debate though). I've pretty much found the same thing that you have regarding squealing (luckily I only have one that's bad but it's a real favorite of mine). After various treatments (drying with silica gel, Last) it worked great for just a couple of passes and then reverted to it's old tricks. For me, one of the worst things about sticky shed is that what makes it squeal. The binder that holds the oxide on the backing is mixing with moisture (hydrolysis) and changing to a tar like substance. This gets on the guides and heads and the friction of the tape moving across it makes it stickier. Since this stuff is now on your machine, it makes tapes that don't squeal squeal. That stuff is real tough to get off and I use the strongest head cleaner I have. It gets into the inside edges of the guides (since the tape edge is where the binder is most exposed to moisture and friction) so you really have to get a magnifier and good light to be sure you've gotten it all.
So, is there a practical solution to this problem for us listeners. There's baking of course (like Larry's dehydrator). That was the cure that Ampex came up with when the problem reared it's ugly head. Unfortunately, it's only temporary but you can almost always get a pass or two to transfer the contents. The Last tape preservative, as you found, doesn't work for true sticky shed tapes. My experiment (which is still ongoing) with silica gel gave me a couple of days worth of clean playback but I returned the treated tape to my shelves and when I tried playing it after a few days, it started squealing again. I've since returned it to the sealed bag with several lb.s of gel and haven't tried it again.
What I'm thinking is that a combination of all the above might work the best. The process I have in mind would be as follows;
1. Bake the tape as outlined by eddie Ciletti http://www.tangible-technology.com/tape/baking1.html
2. Treat with Last tape treatment
3. Store in a sealed bag with a few silica gel packs
You can forgo step one and dry the tape with the gel alone, but it takes a very long time (months) and each time you pull the tape out to check it , it's going to begin absorbing moisture. I just sealed mine up and forgot about it for almost a year! (which was cool with me since I really did forget about it!.
The Last will reduce the friction that exacerbates the problem.
And hopefully, storing it with the silica gel will keep the tape from going bad.
This might seem like a lot to go through but it really depends on how many tapes with this problem you have, and how much you want to listen to them on the original tape.
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What I'm thinking is that a combination of all the above might work the best. The process I have in mind would be as follows;
1. Bake the tape as outlined by eddie Ciletti http://www.tangible-technology.com/tape/baking1.html
2. Treat with Last tape treatment
3. Store in a sealed bag with a few silica gel packs
You can forgo step one and dry the tape with the gel alone, but it takes a very long time (months) and each time you pull the tape out to check it , it's going to begin absorbing moisture. I just sealed mine up and forgot about it for almost a year! (which was cool with me since I really did forget about it!.
The Last will reduce the friction that exacerbates the problem.
And hopefully, storing it with the silica gel will keep the tape from going bad.
That is the most comprehensive plan I have seen for dealing with this issue.
I would add making a dub (analog R2R or gulp, digital) that you can live with while the tape is in a playable state. But try to preserve the original.
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Steve, I dunno, I don't see a lot of gunk on my deck after I play one of these and it is pretty easy to clean. I did notice that another tape that does not exhibit squealing did so when I played it right after the Mahler 2 (this was the BC Unicorn Mahler 3 conducted by Horenstein) and did not do so after I cleaned the deck....so maybe this is early sticky shed. I am going to give this all another try, as mentioned. If it doesn't work, I go to step 2. All of the content of these tapes is available on vinyl, either new or used, but I would really like to fix these tapes. It bothers both the collector in me as well as the conservationist.
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Tom, I've done the dehydrator only once on a double reel masterdub that was 15ips 2 track on 10.5" reels. It was definitely shedding and messed up my Bottlehead Technics badly. I spent a long time cleaning it up. When I completed the dehyrating according to the article referenced, I immediately made a copy with my ATR-700. I then junked the tapes, saving only the empty reels. I have over 100 Barclay Crockers, most all of them bought new as a subscriber like you in the early 80's. So far none of them that I have listened to recently have squealed - keeping my fingers crossed. I did buy in that same era a few (5 in total) from DTR (Direct to Tape Recording) by Bob Sellman. I think all of them have sticky shed syndrome. I haven't gotten around to dehydrate them yet. I'll post the results. Probably if it works, I will probably just dub them onto new tape. They are all 4 tr 7.5ips, dbx II (he calls it Type X) encoded. One thing nice about dbx is that they don't have a reference level like dolby B - so you don't have to be precise in level matching when you dub them.
I have used LAST preservative on all my prerecorded tapes, probably beginning 10-15 years ago - can't remember exactly when. I would treat them as I picked them up, typically used. I don't remember whether I did the B-C tapes when I bought them, but if not, they weren't all that old when they were treated. So I may have prevented the squealing by doing the treatment early.
I have used the LAST tape head treatment on my tape recorders - mostly my old Akai 747dbx. But I did apply some recently (yesterday) to both the Bottlehead Technics and ATR-700. Can't say I hear a difference, definitely doesn't sound worse - maybe a bit better, but I also cleaned the heads thoroughly and demagnetized both machines at the same time.
Larry
Larry
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I forgot to say that I use the head treatment pretty religiously. I can hear a very slight increase in the highs on some of the tapes. What I really like about the entire Last system is I don't have to clean my heads nearly as often. The tape treatment seems to clean the tapes pretty well and I almost never have drop outs after I've used it (of course if the tape is physically damaged, no snake oil in the world is going to help). I think it's because of the tape treatment but the only area of my machine that ever gets much any oxide is the capstan (and that's just barely visible on a q-tip after 10 tapes or so). For the most part, the head treatment lasts a real long time so I don't mind the cost.
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How often do you guys demagnetize and what do you use?
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Any comments on this one or are there better demagnetizers?
http://usrecordingmedia-store.stores.yahoo.net/handmagdebyr.html
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Hi Steve:
Your Studer A810 should need very little demag other than the heads since most of the guides, roller, and other parts that touch tape are stainless steel or other non-ferrous material. Unless you swap the headblocks often, I would use the Hand-D-Mag, mother of all demag, every six months or so.
I have used consumer demag device with some success for normal uses but if you magnitize the heads accidently by applying power inappropriately (swapping headstack with power on for an example...), it will take the power of Han-D-Mag to do the job properly.
Ki
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I also use the Hand-D-Mag. Very powerful. I have been doing quite a bit of recording on my Ampex ATR-700 recently and I demag before any long recording session. Make sure the machine is off and you don't have any recorded tapes nearby!! Larry
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I think that the RB Annis is the gold standard for current production demagnetizers.
I use mine a few times a year. It all depends on how many hours you put on your machine and the material that the heads are made of. You don't have to go crazy and do it every month (I use my machine every day for a couple of hours). I have a little meter that RB used to sell as a kit with the demag and if I get any deflection of the meter I do it. I'd say that every three months should be fine for most folks.
One thing that I can't emphasis enough is when you demagnetize your tape path (make sure and do all the metal parts that contact the tape) is turn off your machine before doing this. You can damage your electronics or VU meters since it's like applying a gazillion dB signal!
For those who've never ruined a VU meter, take it from someone who has more than once, these are extremely delicate devices. To react quickly and accurately, they are very low mass in nature and one uneducated touch of a finger to it's movement will destroy them. So, never open one up. If the spider that you want to get out of it is dead, live with it's withered corpse and maybe name your machine after it.
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Thanks guys.
So last question is what do you do after you (of course) turn off your machine to demagnetize.
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I use the Hand D Mag from RB Annis - comes with instructions. I demag about once per month.
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Thanks guys.
So last question is what do you do after you (of course) turn off your machine to demagnetize.
This is probably as good of explanation as any from "the man himself" Jay McKnight, from "the site itself" MRLabs, on all things regarding magnetic recording.
http://home.flash.net/~mrltapes/mcknight_demag.pdf
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Thanks Steve
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I re-read that entire article again after I posted the link, and although it gives a lot of semi-technical info about the process it is somewhat light on specific procedure.
It seems that the whole idea has been somewhat over-dramatized in tape recorder lore in that it has to be done a lot, and if you do it at all wrong you will make matters worse.
Jay's article seems to debunk some of the more commonly held myths.
As to exactly how I demagnetize (feel free to correct me here fellow Tape Project experts), I turn on the unit about 3 feet from the recorder, move in fairly rapidly and touch each metal part (heads, guides, capstan etc.) with the protected tip of the demagnetizer and move a few inches away fairly slowly at first, in a circular motion, then back in for the next part etc., NEVER turning off the demagnetizer near anything. When I have covered all pieces, I typically move back in fairly close to the center of the whole general headblock area without touching anything and then out again in increasing diameter circles as I had for each individual part, till I am about 3' away or however far I can reach and/or the cord will let me go before turning off the demagnetizer. The main thing is to not turn the demagnetizer power on and off close to the heads or other parts, and to get close enough to each part and not jerk the demagnetizer rapidly away at first from the part. As you get further away how smoothly you move becomes less critical. Of course you also don't want to actually scratch the heads with an unprotected metal tip.
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When I'm moving the demagnetizer to and from the machine, I remember what Duncan Idaho told Paul Atreides "It's the slow blade that penetrates the shield!". If you saw the movie of Dune, your movement should be kind of like that. When you get within a foot and a half or so, move in slow motion like there's a shield surrounding the heads. Then when you back out far enough, you can move normally. The only difference is that you have the energy field in your hand.
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I think our techniques amount to the same idea. I was taught to use circles starting with just moving around a tiny bit within the space of the actual metal piece you are working on, then like an ever increasing diameter spiral as you move out. Perhaps visualizing a cone shaped spring as your path would help. This keeps you in close proximity for a bit if you don't move too fast, and lets you do some movement that gradually decreases the field (which is the point) without having to move veeerrrry slowly away in a linear fashion which also works. I am a bit of a klutz and my hand is not completely linear so the critical part of not jerking or moving too fast or eratically in very close proximity to the heads etc. is better handled by me with the retracting in larger circles technique. However you do it the first part is the most critical, probably up to an inch or two away. I don't think it falls off in a linear fashion so as long as you don't rapidly change the field when within an inch or so you should do no harm. You might have to linger a bit longer almost, if not touching, the part if you have a normal home demagnetizer and you suspect a big issue with some part. Not such a big deal from just normal playing or even recording of tapes unless your machine circuitry is messed up and trying to put DC across the heads or you adjusted the guide with a magnetized screwdriver. If that is the case it needs to be fixed THEN thoroughly demagnetized.
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Is there risk to any of my adjacent components as long as these are powered off?
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I was about to respond to your question Steve as saying simply," I've never heard any warning about equipment, or had any problem from demagnetizing,.." and I was going to add the caveat " but you might survey the immediate area before using it to be sure that there are no tapes, or devices which have hard drives in them". But as I thought about what I was just about to type, I looked over at my Technics and realized that 4 inches on the right of my machine is the cabinet that holds about 100 of my tapes and 10 inches below it, is my Mac Pro! I guess I might think about rearranging some things!
That reminds me of the first time I took a patient (I'm an RN) to have an MRI done. The procedure at the time was to ask the patient 3 times whether they have any metal objects within their body and once in writing. I did this and while wheeling my patient through the long underground corridors to the MRI dept. (it's always isolated from the rest of the hospital) I went over the checklist in my head. I asked the patient one more time as I when I got the patient into the MRI room on a plastic gurney and when I got within about 10 feet of the machine, my metal clipboard, stethoscope, and every pocket I had jerked towards it! It took everything I had to keep them from flying away and not to show the panic I was feeling to the patient. As I walked out (I never shoulda been in there in the first place) I could see the techs laughing their asses off.
Now that's a strong magnetic field! Obviously, your RB Annis is nowhere near this strong and I haven't had any problems with my tapes or hard drive, but there's no reason to test fate.
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Again, I defer to the opinions of others here and there is no accounting for what subtle effects might be noted in audiophile circles, but the answer would be no. I don't think you could hurt anything. The field decreases rapidly with distance from the probe end.
The "having the equipment off" part is so you don't accidentally induce a loud hum or pop into the electronics. The demagnetizer produces an AC field at 60Hz at the tip while it is on, but it makes an inductive spike pulse when it's power is turned off. Again, see the Jay McKnight article.
It is basically an AC coil hooked to the 120V power line and works on the same general principle as a bulk tape eraser or one of those rings that they used to use to degauss (demagnetize) the shadow mask of a color picture tube. The idea being if you put an object in a strong magnetic field that reverses polarity rapidly at 60Hz line frequency, then slowly reduce that field to zero, you remove whatever "permanent" magnetism has built up and leave the object at "zero" magnetic potential.
In effect that is exactly how the erase head on the recorder works as well. It puts the (much higher) bias frequency with no signal on the tape to erase whatever magnetic signal used to be there.
I suppose a mechanical VU meter might be an issue if you get the demagnetizer probe too close, or tapes themselves. Perhaps you could subtly physically distort the relationship of the elements within a small delicate tube with a very big demagnetizer, but I think you would have to try very hard to do that.
Just don't turn the power off or on near anything or get it close to your tapes or mechanical VU meters.
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I looked over at my Technics and realized that 4 inches on the right of my machine is the cabinet that holds about 100 of my tapes
I wonder how many people have stored their tapes right next to their bookshelf loudspeakers with big woofer magnets through the years and if anyone has noticed an effect from it.
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Thanks for all of the great advice guys and sorry to have taken the thread off topic.
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Yeah, like I said, I've never noticed any problem with those tapes and I store some of my favorites in the closest spot. I have heard rumors that laying tape against high efficiency speakers with huge permanent magnets have had problems.
In the "Tape Basics" part of the Beginners Guide, I tried to impress upon the reader how drasticly distance effects magnetic force. If you place a couple of pages of paper under a fridge magnet, it holds it up just fine. If you increase those pages, the magnet will no longer hold the pages to the fridge. If you investigate the reason by pulling the magnet off with different thickenesses of the same paper, you'll see that it isn't the wieght of the papers, it's the decrease on magnetic attraction.
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And just how did my original thread get so hijacked?
Actually, the discussion on demagnetizing is a good one, and perhaps someone more technical than I am can extract the info and add it to a sticky on RTR basics.