Corey Bailey
           Audio Engineering
So, how do I do it? The analog-to-digital transfer of the material is done only once, but two digital files are created simultaneously. This provides for the least amount of risk to the source material. I create both digital files simultaneously, using two separate computers, because I’m not a big fan of sample rate conversion.  One file will be for archival purposes, and will be at a bit depth of 32bits and a sample rate of 48 or 96 kHz, depending on customer preference. The average archival file will be at 32bits, 96 kHz (32/96). The second file will typically be at CD quality (16bit, 44.1 kHz although, I have been using a bit depth of 32bits for the second file which can offer more precision when it comes to restoration (if necessary). The second file can be any of the available sample rates and bit depths that the customer prefers. In addition to .wav, I can  provide MP3, FLAC or just about any audio file format the customer wishes. The end product is up to the customer. Although there is no extra charge for the inspection and preparation process, in all cases, if anything out of the ordinary is encountered during the inspection and preparation process, the client will be advised before proceeding. ANALOG TAPE Reel-to-reel tapes have to be individually inspected and often will take the most time to prepare for transfer depending on the number of splices, etc. that may need attention or replacement. The type of tape has to be identified and assessed as to condition, playback format and speed. Tapes are inspected by hand, cleaned, and splices are replaced as necessary. Leader is added to the head and tail of all reel-to-reel tapes for those tapes that don’t have leaders. This allows for the complete transfer of the tape “end-to-end.” Having both ends of the tape leadered protects the head end of the tape with a few wraps of leader and the tail of the tape from the threading slots that are built into most reels. If leader is added to a tape that has leader attached, the existing leader type will be matched. If needed, polyester-based tapes will be hand lubricated or baked. The baking of audio tape(s) is only done as a last resort and customer approval is always sought if baking or lubrication is deemed necessary. Acetate backed tape was used from the beginning of widespread audio tape recording to about 1970 or so. The most common problem that Acetate backed tapes suffer, is a condition known as “Cupping.” This is a condition where the tape curls from edge to edge forming a shape similar to a metal Venetian blind. Depending on the severity of the condition, the results can vary form an uneven pack to oxide shed. Cupping is caused by shrinkage over time of the Acetate backing. An uneven pack is not uncommon for acetate tapes that have been stored for long periods of time on reels with smaller hubs. The tape tends to hold the shape of the wind the closer to the hub the tape gets. This condition is generally irreversible and, more often than not, the tape will simply have to be returned to storage with an uneven wind. If the Cupping condition is not severe, there is a possible treatment that can be done. Acetate backed tape can sometimes be re-moisturized, if needed. These processes take time and (again) customer approval would be required. All cassette tapes undergo a visual inspection first, looking for any anomalies. This visual inspection includes checking the condition of the pressure pads for those audio cassettes that use them. The tape is then fast-forwarded and rewound while listening for anything out of the ordinary. The fast-forward, rewind process does two things: First, it exercises the tape which has usually been stored for sometime and Second, it will indicate to the operator that all of the internal parts of the cassette shell are operating correctly. It is only after this visual inspection and rewind process that the tape will be transferred. If any problems are noted in the inspection process that would impair the transfer, the tape will be set aside and the customer notified. ANALOG TAPE BAKING (The Short Story) The process of baking analog tape involves raising the ambient temperature of the tape to 118 -125 degrees Fahrenheit in a very low humidity environment for specific amounts of time based on the thickness of the tape, size of the reel and the number of reels involved. The process was first proposed (even patented) by Ampex Corporation in the early 1990's. A surprising amount of analog tape manufactured from the mid to late 70's to the mid 90's (and later) suffers from a problem with the oxide known as Sticky Shed Syndrome. Much has been researched and published on the subject and links to more in-depth reading can be found on the links page. The problem was mainly with professional grade audio tape; however, several varieties including consumer brands are showing signs of the problem after long term storage. The Digital Audio Tape formats (DAT, DTRS, etc.) have recently shown signs of Sticky-Shed so if you own any of these, now is the time to inspect them. Unfortunately, the rotary head formats will not show a problem until they are played and, then it can be too late for your prized digital audio recorder. Since I consider tape baking to be a last resort I will use a much lower temperature and allow more time for the dehydration process. I will first try a good cleaning and lubricate the tape as described next. TAPE LUBRICATION For non-acetate base reel-to-reel tape, I use lubricants manufactured by Last Factory. If needed, the lubricant is applied manually during a forward or rewind shuttling process at a very low speed. This process is labor intensive but I have found it to be effective for about 90% of problem tapes with a polyester base. I have also found it effective for some acetate base media: namely acetate base magnetic film. Magnetic film has a much thicker acetate base, and oxide layer than audio tape (About 5 times thicker). My equipment has been modified so that the customers audio tape never touches a stationary object (like tape lifters or stationary guides) during the inspection or lubrication process to avoid unnecessary stress on the valuable oxide that contains the audio. For analog cassettes and micro-cassettes that may need lubrication, I use a modified cassette transport that allows application with a “Q-tip” style applicator. The truth is that the vast majority of analog cassettes seem to have survived surprisingly well considering the often harsh storage conditions that befell them. Usually, they will play when tried, but, as with everything, there are some exceptions. I have posted articles on the lubrication and/or baking of audio and video tape in the “Useful Information” section of this website for those who prefer to Do-it- Yourself. RECORDS Records, often simply referred to as Discs, are inspected and cleaned as needed before transfer. The cleaning solution I use, for those disks that will tolerate wet cleaning, is a simple solution of distilled water with the record cleaning solution available from the Disc Doctor. The cleaning process used is essentially that recommended by the Disc Doctor or the Library of Congress. If interested, you can find out more by visiting the LOC website. I have also written an article about record cleaning. I said “essentially” because the one thing I do in addition to the practices recommended by the Disc Doctor or the LOC is to vacuum the side of the disk being cleaned during each process of the cleaning. There are some varieties of disks that simply cannot be cleaned using any type of wet cleaning solution. Many of the home-made and vending machine records (Recordio, Wilcox Gay, etc.) from the 1930’s to 1950’s fall into this category. These disks are simply brushed carefully with a micro-fiber brush while being vacuumed (if they will tolerate being vacuumed) otherwise compressed (canned) air is sometimes used in addition to brushing. Lacquer discs require special handling and inspection before any type of cleaning is used. Lacquer discs that are suffering from de-lamination will require a separate quotation (and approval) after inspection before any restoration is undertaken. Part of the inspection process may involve inspecting the grooves with a microscope which helps in the process of selecting the best stylus for playback. Anomalies are noted and any pictures taken will be returned with the digital files. WIRE RECORDINGS The most common occurrence when transferring recorded wire is breakage. Breakage can occur even when the wire appears to be well packed on the supply spool. Should breakage occur during transfer, the wire will be spliced using the recommended procedure (a square knot) and the transfer resumed. The splice will usually result in a small loss of audio because it takes a few inches of wire to make the splice. The lost area of audio is generally small because the playback speed of wire recorders is about 24 Inches Per Second (IPS) and the square knot splice only consumes a couple of inches. RESTORATION As a qualified expert in the field of audio restoration and archival, I’ve worked hands on, full time with it for the last 25 years. Audio restoration that delivers quality results is very labor intensive. It takes time, it’s very tedious and time always equals money. I can offer the best possible restoration available with today’s technology and it’s done on an estimate basis. Typically, I will supply a sample of the material demonstrating what can be done and what it will cost. For individuals with instantaneous recordings, (Lacquer discs, Recorido discs, etc.) I will return a listenable file and the cost will be included in the transfer. Restoration is only done on a copy of the lower resolution (CD quality) files. The original digitized files remain intact as originally transferred and will be delivered as such. The technology involved in restoring and enhancing digital audio files is advancing as you read this, so those archival files that I deliver will, no doubt, someday be able to be restored and enhanced far beyond what is available now. FORENSIC RESTORATION Forensic restoration differs from the norm in that intelligibility is usually more important than fidelity. I prefer to take baby steps when it comes to forensics. This is to avoid the situation where the client spends money only to find out that the source can’t be saved adequately to provide admissible evidence. After inspecting the source and doing some tests, I will generally supply a sample of the material demonstrating what can be done and quoting what it will cost. Legal testimony requiring a court appearance or deposition is billed separately.     Advice is always free so, if you have any questions at all, please contact me. Return to TOP of page © Corey Bailey Audio Engineering
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