Corey Bailey
Audio Engineering
The Ken Slater Tapes The Ken Slater Tapes was a project that I transferred in 2020 and 2021. It was for the Chippewa Historical Society ( For this project, I was initially contacted by Charles Taylor who knew Ken Slater through his father and was familiar with the collection of audio tapes. The tapes were in the possession of Beth Acker (Ken Slater’s niece) and her husband. Charles helped to assess the importance of the tapes and Beth built a spreadsheet to document everything. Ken Slater documented the history and folk lore of the state of upper Michigan (known locally as the Upper Peninsula) by recording interviews with the people who had lived and worked there, including several interviews with representatives of the Chippewa and Ojibwa Native American tribes. Some of the tribal elders did not speak English and had to have an interpreter. The recordings of the Native Americans were made in the late 1940’s. Most of the people interviewed were elderly and recounted their experiences from the late 19 th century and the early 20 th century. The recordings spanned about 20 years, beginning in the late 1940’s (the dawn of consumer tape recording in the US) to the late 1960’s. Besides peoples’ homes, the interviews were conducted in rest homes and hospitals, wherever the interview needed to be held. On one particular tape, I could hear the pump of an iron lung in the background. Although the majority of the recordings were about the Upper Peninsula area of Michigan, there were a couple of recordings about the Pacific Coast of the US, which included the migration from Michigan in the 1800’s. Ken Slater started this project when the Brush tape recorder first became available. A Wollensack T-1500 is still with the family. However, there must have been another tape recorder used because many tapes were recorded in Half Track Mono before the T-1500 was available. There were three recording formats involved. Most of the tapes were recorded 1/2TR. Mono. There were five paper base tapes recorded in the Brush Mono format (a unique full track format). Additionally, there were, at least, two tapes that were recorded Full Track Mono. The Full Track Mono tapes were recorded externally and sent to Ken. I asked about previous recordings or technologies and apparently there were none. I feel that I got to know Ken Slater through his work. Overall, he was a good recordist and paid attention to the details, as the vast majority of the tapes were well recorded and, except for the earliest recordings, were voice slated and the tape boxes were labeled. The interviews were typically recorded at 3-3/4 IPS. When more fidelity was needed, 7.5 IPS was used. The stories told by the subjects were interesting and I found myself listening to them while transferring the tapes. The tapes consisted of one hundred eighty-one reel-to-reel tapes. One hundred sixty-eight were on 7” reels and there were thirteen, 5” reels. One hundred twenty-four of the transferred tapes were sent to The Chippewa Historical Society, twenty-one were family recordings of interest and thirty-six were not wanted or blank. One hundred thirty-one were acetate base tapes. All were recorded 1/2TR. Mono. The brands included Irish (all types), Permo and Scotch. There were approximately twenty-one acetate base tapes in plain boxes. I suspect that this tape was purchased in bulk (or, in the bargain bin) as almost all were poorly slit and some were factory spliced. This particular tape did not fare well with the mold remediation process. Of the acetate base tapes, thirty-six were moldy and thirty-three were isolated. There were thirty-three paper base tapes (Permo brand, T-88R). Since the majority of the paper base tapes were 1/2TR. Mono, I suspect that they were reused. There were seventeen polyester base tapes of various brands and all were recorded 1/2TR. Mono. Four were moldy when received and all were isolated. Most of the polyester tapes were 1mil (1800 feet) and played for 1.5 hours at 3-3/4 IPS. A few were .5mil (2400 feet) which played for 2.5 hours at 3-3/4 IPS. In 1925 Ken Slater was married to Ada Giles, according to his niece, Beth Acker. Ken originally stored the tapes in a metal storage cabinet in a woodshed attached to their house in Hulbert, Michigan. The woodshed had no heat, had some gaps in the wood and snow would blow into the shed in the winter. The tapes were exposed to heat in the summer as well. Being in the middle of the woods in the North of Michigan, the temperatures would never be hot by most standards, although there might be one or two hot days in the summer. The woodshed was also plagued with mice, squirrels and insects. The metal storage cabinet helped protect the tapes from the larger critters. Ken remarried in 1966 and moved the tapes to a house he had built in Traverse City, Michigan. Unfortunately, he stored the tapes in cardboard boxes in the attic area that was not insulated. It got very cold in the winter and hot in the summer, as the side where he stored them faced the West. Winds and lake effects from Lake Michigan and the West Bay didn't help either. So, the tapes were, once again, exposed to harsh conditions. The tapes had been tossed out in 1987, the a result of a house cleaning, and were rescued from a dumpster by Beth and her husband. When the tapes were rescued from the dumpster, they were moved to Clarkston, Michigan and stored in an air conditioned basement in that same metal storage cabinet which, had been cleaned up for the move. In 2016 the tapes were moved to Irons, Michigan. Again to a finished, air conditioned basement. The tapes were shipped from Irons, Michigan to Southern California in 2020 and 2021, where my studio was located. Thirty-six of the acetate base and four of the polyester tapes base tapes were moldy when received and had to be separated for treatment. I’m not sure if it was mold or some other type of fungus because I observed both light and dark spots. For the sake of simplicity, I’ll refer to the problem as mold (mold is a fungus). Some spots appeared on a few of the tapes, apparently as a result of the tapes adjusting to a dryer climate. Those tapes were judged as low to moderate and not removed and placed with the other moldy tapes. However, they were treated for mold. The mold remediation process that was used: I chose white vinegar because of the acetate base tapes. I normally use denatured alcohol or hydrogen peroxide on polyester base audio tape, but any kind of alcohol will damage acetate. I could have used hydrogen peroxide, but you can’t mix it with vinegar and I felt that white vinegar would work best on the boxes which, were to be saved. The remediation process was completed outdoors. While wearing a N95 respirator and long rubber gloves, I sprayed the tapes and their associated boxes with white vinegar outdoors and set them in the sun to dry. The reels of tape were turned at least once while drying in the sun. This was done about four times over the course of a week. Then, while suited up completely in personal protective equipment (PPE) and wearing a respirator, I wound the tapes from one reel to another, one at a time, using an 8mm film editor that had been modified by yours truly. While being transferred, the tape was wiped, on both sides, with a cloth soaked in white vinegar. The empty original reel was then soaked in denatured alcohol, dried and the tape was rewound, onto the original reel, while being wiped (a second time) with a white vinegar soaked cloth. The tape box was sprayed again with vinegar, before the reel was placed in it, and the whole thing was set indoors to dry. After about 2 days, the tapes were checked for any signs of mold. There was none. The tapes that were judged as low to moderate received the same treatment as those that were isolated except that they were not treated using the 8mm film editor. Instead, they were wiped with a vinegar cloth in both directions, while being leadered by me. At the end of the day, all equipment, including the work surfaces, were sprayed with 91% isopropyl alcohol. Of the thirty-three paper base tapes, seventeen were stuck to one side of the reel. and six of those were judged by Charles Taylor as high priority. Fused may be a better term for this, as there was some kind of process that happened over time. Apparently, a chemical (or chemicals) that was used in the oxide or perhaps to bind the oxide to the backing, reacted with the plastic used in the reel. Some reels were worse than others. That and the fact that the reels were only stuck to one side, indicates to me that storage conditions were a factor. There was no budget for chemical analysis, so I moved on to inventing a process for un-sticking the tapes; I selected a piece of ¾” plywood, slightly larger than a 7” reel, and covered the work area with strips of 2” masking tape. I traced the circumference of an empty 7” reel in the area where I added the masking tape and placed two padded screws strategically on the edge of the tracing. I then screwed my homemade jig to the edge of a workbench so that I could push against the reel to be operated on. I started by using the thinnest blade possible. After several tools, I discovered that a commercial pastry knife (that I had bought at a yard sale) worked the best because I could use both hands to apply pressure. I wore a pair of cutting gloves (the kind that chefs use), since one hand was on the blade of the knife. The tape pack stayed intact during the process. For the un-spooling process, I used the Shuttle Mode of a tape deck as slow as it would go. Paper base audio tape is very, very fragile and sometimes the breaks involved every wrap of the tape. For getting the end of the tape out of the ¼” reel, I sharpened the end of a ¼” wooden stir stick. Obviously, I wound up with a reel of audio tape that had many splices. Some of the splices were very long because the tape had torn longitudinally. In the end, it was worth it because all thirty-three of the paper base tapes played just fine, although some of them had several splices, and long ones at that. All tapes were leadered on both ends and checked for recorded format and integrity. Leader on both ends of the tape will protect the outer layers of the recorded material and provide some isolation at the hub from the threading slots. Plus, having leader on both ends provides the ability to transfer the entire recording because some consumer tape recorders were very good at recording right to the end of the tape. The paper base tapes were primarily leadered with paper leader. The exceptions were those paper tapes that were over-full. Those tapes were leadered with plastic leader. The acetate and polyester tapes were leadered with plastic leader. Some of the acetate tapes had the original factory tab that had to be cut off in order to add the leader. In those instances, the original tab was placed in the box. The rest were secured with masking tape. Masking tape was also used as markers on some of the tapes and had to be removed before the tape was transferred. The tapes were transferred and shipped in two groups; For the 1 st group, the audio signal was split into 2 RME Multiface A/D converters. Each converter was controlled by its own computer, one running at 44.1kHz and one running at 96kHz and neither computer was connected to the internet. After digitizing about half of the 1 st group, I realized that it would be better if the tapes were played only once because of age and fragility so, I changed my workflow for the 2 nd group. For the 2 nd group, the tape decks were played into a MOTU M2, A/D converter that was controlled by a computer running recording software at 96kHz. The 1/2TR. Mono, tapes were transferred as two channels (one pass). All of the those files were then edited to one channel each (Mono). The backwards channel was reversed** and then both channels were re-sampled to 44.1 kHz. All of the original files (transfers) were saved. The editing for listening was done on a copy of the 44.1 files which, became part of the deliverables. For the listening files, the blank space was shortened to about 3 seconds, some of the recorded hum was removed and the files were adjusted for gain so that they will all be the about same volume when played. This was done for both groups. Sides 1 and 2, of the transfers (tapes) were not joined. All tapes in the #2 group were played heads out, regardless of the reel designation or recorded material. Thus, on the tapes that were 1/2TR. Mono, Side 1 may have not been the beginning of the recording. On those tapes, Side 1 is the Left channel and Side 2 is the Right channel. However, when separating the files, every effort was made to put things in the proper perspective for listening. Of the thirty-six tapes that were not wanted, those that had been recorded were transferred at 48kHz. The recording software used was iZotope RX. The editing of the digital files was done with iZotope RX and Sound Forge. Frequency analysis of the supplied material showed an average frequency response from 50Hz to about 10kHz. The Full-Track Mono tapes, recorded at 7.5 IPS, showed a slightly higher frequency response of 12kHz or so. The 1/2TR. Mono tapes were transferred using an Otari MTR-15. The Full-Track Mono tapes were transferred using a Nagra 4L. The Brush format tapes were transferred using a Pioneer 1020Q (a 4 channel, Quarter track), using channels 2 and 3. Ken Slater (1900–1983) always said that he lived during the best years. He got to see people go from horse and buggy to landing a man on the moon. Ken could talk to anybody, king or pauper. From a genius to the mentally challenged. **In the analog era, I used to make copies of master tapes backwards because the copy came out sounding better. Both tape decks have to be carefully aligned (which should done anyhow). I used to use the analogy of a cymbal crash when explaining the process; A cymbal crash (sonically) has a vary steep leading edge (Rise Time), then trails off into infinity. A tape head is a coil of wire that is wound around a piece of steel that is shaped somewhat like a horse shoe. Thus, it does not have a steep rise time. So, playing a cymbal crash backwards provides a better analog copy because the tape head can track the rise time much better. I would like to thank all of those who helped to edit this document. Especially my daughter: Megan R. Bailey, Ph.D. Return to TOP of page © Corey Bailey Audio Engineering
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