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 24 or 32bits and a sample rate of 48 or 96 KHz, depending on customer preference. The average archival file will be at 24bit, 96 KHz (24/96). The second file will typically be at CD quality (16bit, 44.1 KHz) although, I have been using a bit depth of 24 or 32bits for the initial CD files which can offer more precision when it comes to restoration, if necessary. The second file can also be 16/48 or 24/48 for DVD Audio playback. In addition to the above file formats, I can  provide MP3 or just about any format the customer wishes. The end product is up to the customer. 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 will be added as necessary. If needed, polyester-based tapes will be hand lubricated or baked. Customer approval is always sought if baking becomes necessary. ANALOG TAPE BAKING (The Short Story) The process of baking analog tape involves raising the ambient temperature of the tape to 125-130 degrees Fahrenheit in a very low humidity environment for specific amounts of time based on the thickness of the tape and size of the reel. 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. I consider tape baking to be a last resort and, if I have to resort to the baking process, 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 analog reel-to-reel tape, I use lubricants manufactured by Last Factory. If needed, the lubricant (Tape LAST) 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 tapes although lubrication of acetate tape is only undertaken as a last resort. My equipment has been modified so that the customers audio tape never touches a stationary object (like tape lifters or stationary guides) during this 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. 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. Scroll down to: “Cleaning Audio Visual Materials.” 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 each side of the disk being cleaned during the cleaning process. 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 1940’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). Lacquer discs need special handling and inspection before any type of cleaning is used. Lacquer discs that are suffering from de-lamination will require a separate quotation after inspection before any restoration is undertaken. Part of the inspection process involves inspecting the grooves with a microscope  which helps in the process of selecting the best stylus for playback. 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 22 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. 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 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 © 2012 Corey Bailey
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