by BERT WHYTE
I BAKE FOR WHALES
It is hardly surprising that consumer-type open-reel tape recorders have fallen on perilous times. They now compete with many high-quality cassette decks and soon with the even higher levels of performance afforded by the forthcoming Dolby S-type cassette decks and the imminent arrival of R-DAT recorders. Revox, Teac, Otari, and Fostex still offer a few models of upscale open-reel tape decks, but less expensive audiophile-type open-reel decks have literally disappeared from the market.
Open-reel tape was a dual-purpose medium. Audiophiles used it to make high-fidelity recordings, and in a broader sense, open-reel tape decks were used to play back prerecorded tapes. There has always been a certain elite aspect to open-reel tape. Those who could afford it enjoyed stereophonic sound, via prerecorded tapes, four years before it became available on vinyl discs.
In the early days of open-reel tape recorders, before the general availability of prerecorded tapes (around 1954), audiophiles had to make their own recordings. Most of these recordings were decidedly amateurish, both sonically and musically. However, there were insider groups fanatically devoted to recording or acquiring tapes of the highest professional quality. One of these groups became the Tape Bootlegging, Chowder and Marching Society, of which I was a charter member. Being a sales executive and musical director of Magnecord greatly abetted my recording activities. In most cases, we asked for permission to make our recordings.
But since the musicians' union viewed our activities with a jaundiced eye (even though we assured them the recordings were of an "experimental nature"), we usually found a way to circumvent their lack of cooperation through technology or ingenuity.
For example, the United States Navy Band was captured stereophonically with a pair of appropriately spaced omni mikes lowered through the ceiling skylights of an auditorium in a suburban Chicago high school! Guys and Dolls, starring Allan Jones, was recorded in stereo with the mikes planted in the footlights of a Chicago theater.
Gene Krupa, Ella Fitzgerald, Roy Eldridge, and other performers of "Jazz at the Philharmonic" were stereophonically recorded in Carnegie Hall with the unspoken consent of the concert promoter. There were many other clandestine recordings, including one in which two people equipped with wireless microphones sat about 12 feet apart in the third row at a Metropolitan Opera performance, transmitting to an accomplice with a portable tape deck in a car parked outside of the theater! Supposedly, authorities at the Met found out about this and subsequently set up equipment to jam any future transmissions.
Many people have libraries of tapes they have personally recorded, and record companies have thousands of master tape recordings in their vaults.
Whether amateur or professional, these tapes have been recorded on a variety of tape formulations, some dating from the earliest days of recording.
Most record companies take precautions in storing their tape masters, while most amateur recordings are usually stored under the conditions of the typical home environment. 1 have acetate and even some paper-base tapes dating from 1948 which have been subjected to home storage conditions, and except for some cupping (due to plasticizer dry-out), they are still playable. Apart from the ever-present problem of print-through, it seems that most magnetic tape recordings do remain playable for fairly long periods of time.
However, in recent years a devastating problem has developed with recordings made on certain types of magnetic tape. The problem equally affects all amateur and professional open-reel recordings. Imagine threading a valuable and possibly irreplaceable open-reel recording on a tape machine for playback. After a few revolutions of the reels, the machine grinds to a stop. Pressing fast-forward or rewind may move the tape a half-turn or so, but it stops again! A condition known as stiction has developed.
Cleaning tape guides or heads will not alleviate the problem. I know some heartbroken people with hundreds of open-reel tapes afflicted with stiction.
Stiction is a term coined to describe the very high friction forces between the tape and the guides and heads of a tape machine. As noted, stiction can be great enough to stop the tape drive, even with the 1-horsepower motor of a Studer professional recorder.
Most stiction problems involving open-reel tape have occurred with various tape formulations made between 1970 and 1976. Stiction has occurred with tapes made before and after that time, but infrequently, and is probably more attributable to environmental storage factors than to inherent flaws in the tape.
Believe it or not, the aggravated stiction problems with the faulty tapes can be traced to that great leviathan of the ocean, the sperm whale. These whales have a huge cavity in their heads filled with sperm oil. Along with the iron oxide, binder, and plasticizer in tape coating formulations, a modified sperm oil was used as a lubricant. Sperm oil was used in many other ways, and its demand was so great that these whales were being hunted to the point of extinction. In the early '70s, sperm whales were placed in the endangered species category, and most of the whaling nations agreed to greatly curtail or altogether stop the hunting of these magnificent creatures.
Without diminishing the importance of magnetic tape, it seemed proper that modern technology produce an appropriate tape lubricant without killing whales for sperm oil. Whether it was undue haste or some other factor, the tape lubricant used in place of the sperm oil in those problem tapes had the unfortunate tendency of seeping out of the tape coating, causing the high friction. In extreme cases, the oxide surface could leave a gummy residue along the entire tape path.
Jim Wheeler, an engineer in the fields of head and tape design with Ampex Corp., points out that in tapes with the lubricant/stiction problem, the actual magnetic recording is still perfectly good. Obviously, the implications of this stiction problem are different for an audiophile who wants to play back his tapes for his listening pleasure than they are for the record company engineer who wants to play back an analog tape master for transfer to digital tape and subsequent CD manufacture. The record company needs just one "good pass" to make a digital copy, whereas the audiophile would like his tapes to be usable for repeated playback. With the availability of RDAT recorders, the audiophile will also be able to take advantage of the "single-pass" tape transfer to the digital tape.
With a $150 air-convection oven, you can bake your tapes overnight, and the hot air will redistribute the errant lubricant.
To counteract stiction, Wheeler suggests obtaining a DuPont chemical called Krytox. Krytox is sold through scientific or chemical supply houses, or check with DuPont. Mix a solution of 1% Krytox and 99% Freon TF. Then buy a fabric called Pellon from a dry goods store. (A soft, lint-free cloth will do in a pinch.) Make a pad of the Pellon, and saturate it with the Krytox solution. Tapes with stiction problems can be rejuvenated enough to make a few passes through the program by running the oxide surface of the tape over the Krytox-soaked pad. (Incidentally, Wheeler says that the heads on a videocassette recorder never need cleaning! He says it is the tape guides that cause problems with videocassettes and suggests using an Allsop video-cleaning cassette moistened with the Krytox solution.)
While Krytox is a temporary expedient to obtain playback of a tape afflicted by stiction, a more elaborate, expensive, and time-consuming method exists: Baking the tapes! If you have an extensive collection of tapes with stiction problems, consider purchasing an air-convection oven, which costs about $150. A candy thermometer is used to set the oven to 130°. The stiction tapes, quarter- or half-inch, can be stacked on top of each other, six to eight tapes at a time. They are literally baked for a minimum of six hours but preferably overnight. The convection oven's hot circulating air redistributes the errant lubricant. With this method, Wheeler says, a dozen or more playbacks are possible, and the baking process can be done again. He has cycled tapes through the process quite a few times without causing apparent physical or sonic degradation.
Many people worry about accidental erasure of tapes from motors, airport security devices, nearby TV sets, and other magnetic forces. Wheeler points out that a tape held just 16 inches away from a junkyard electromagnet having a lifting capacity of 800 pounds will show just a 5% loss of signal. However, some microphones and headphones have magnetic fields strong enough to cause some second-harmonic distortion when placed on top of a reel of tape.
My understanding is that further research and development of tape lubricants since 1976 has eliminated the problems of stiction in newer tapes. As for those older ones, I'm sure the baked tapes don't have the olfactory appeal of freshly baked bread, but at least their auditory appeal can continue to be enjoyed!
I want to gratefully acknowledge the help of Jim Wheeler in providing some of the information in this column.
Wheeler is one of the foremost experts in the archivability of tape (audio and video). His article, "Long-Term Storage of Videotape," which was published in the June 1983 issue of the SMPTE Journal, is considered an authoritative reference on the subject and has been reprinted in a number of languages.
Some of the information on open-reel tape is excerpted from Wheeler's April 1988 article, "Increasing the Life of Your Audio Tape," in the Journal of the Audio Engineering Society. Those who have a large tape library will find this article very worthwhile for the information on print-through, environmental considerations for tape storage in home or studio, and many other helpful hints. I would also like to thank George LaForgia, field engineer for Ampex, who provided practical information on tape restoration procedures.
(adapted from Audio magazine, Jul. 1990)
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