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 24 or 32bits and
of 48 or 96 KHz, depending on customer preference. The average
archival file will be at 32bits, 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 be any of the available sample rates and bit depths that the
In addition to .wav or Broadcast .wav, I can provide MP3, FLAC or just about any
audio file format the customer wishes. The end product is up to the customer.
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. The
baking of audio tape(s) is only done as a last resort and 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 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 analog reel-to-reel tape, I use lubricants manufactured by
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 media (mostly acetate base
magnetic film). Lubrication of acetate base audio tape is is usually a matter of
adding moisture and 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 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
. Scroll down to: “Cleaning Audio
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 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).
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. Anomalies
are noted and any pictures taken will be returned with the digital files.
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
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 those 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 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