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
of 32bits and a
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
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.
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
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.
ed tape was used from the beginning of widespread audio tape
recording to about 1970 or so. The most common problem that
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
. Much has been researched and published on the subject and links to
more in-depth reading can be found on the
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.
For non-acetate base reel-to-reel tape, I use lubricants manufactured by
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
I have posted articles on the lubrication and/or baking of audio and video tape in
” section of this website for those who prefer to Do-it-
Records, often simply referred to as
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
. 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
. I have also written an article about
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
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.
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.
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
labor intensive. It takes time, it’s very tedious and time
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
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 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
© Corey Bailey Audio Engineering