The World of Audio Restoration
What is Audio Restoration?
It's something like the restoration of an old art
masterpiece except I work on sound recordings,
instead of visual images. It could be anything
from a favorite piece of music to an "audio letter"
sent home to a loved one during wartime. In short,
just about anything audible, that has ever been
recorded, on any medium, at any time.
With the Compact Disc so widely accepted, many
people no longer have the means to play an LP
phonograph record, let alone your grandfathers
78ís!... and much of that music effectively is lost,
except to collectors like ourselves... most will likely
never be re-issued on CD...
Phonograph recordings have been with us since just
before the turn of the century, and up until the
1950ís, most were very fragile and easily damaged...
and if you dropped one, it would almost surely shatter into small
fragments. Even something THAT seriously damaged
can be restored, although the
process is VERY time consuming, and as you would
Many of the steps discussed here are subtle, resulting
in small improvements. Listening on good quality
studio monitors, however, each step reveals the
improvement, and the whole becomes a striking improvement
over the original condition. Still,
nobody can make a "silk purse from a sowís ear"... if
it isnít in the grooves, it canít be made to magically
How is it Done?
The process of restoration begins with a careful
cleaning to remove all the dirt, dust, fingerprints and
other contaminants that have accumulated over the years.
Did you know that old 78ís could actually go
moldy? They can, and particularly where the discs
have been stored in a damp basement. The mold
"feeds" on the shellac content in old 78's, an organic
compound, it actually comes from an insect found in
India... the Lac bug! Simply put, dirty records sound bad,
even when played with the correct stylus, and for
average 78ís a selection of three stylus sizes 2.0 mil, 2.5 mil and 3.3 mil
conical shapes will do for 90 percent of the cases.
There are so many "old wives tales" about how to
clean your records that a few words about it may be in order.
Purity of the cleaning solutions is a MUST, so purchase a jug of
distilled water from the local pharmacy to use for
mixing and rinsing. Ordinary tap water contains a
variety of minerals, and you DONíT want to leave
them on your disc after cleaning it.
Among sound archivists, the Keith Monks Record
Cleaning Machine is considered to be the best
available, but at roughly CA $5,000 it is beyond
what most of us can afford. My "manual" cleaning
method takes much longer, but works just as well,
and will let you spend what you save on more
records. Most of us like THAT idea!
For dry cleaning of dusty records, a stiff short bristle
brush can be used to get off most of the surface
material and a good part of what has gotten into the
Wet cleaning is generally considered to be the best
way to ensure a completely clean record, and hereís
how to do it with minimum risk to your treasures. A
flat velvet brush is used to get into the bottom of the
grooves and get the dirt out. An easily available
surfactant is Kodak Photo-Flo 200 and it is diluted
in water to the tune of between 5 to 20 ml in 250 ml
of distilled water. (The higher amount produces more sudsing!)
In some really bad cases, a few
drops of liquid dishwashing detergent can be added
to the mix. Always bring the solution to the disc by
amply "wetting" the velvet brush, and scrub until
the surface looks "soapy". This will loosen the dirt
and cause the fluid to flow in an even film without
breaking up into droplets on the surface of the
record. The now dirty fluid can be sopped up with
a piece of white quilted kitchen toweling, always
wiping with the grooves, never across them. Using
a thoroughly rinsed velvet brush, saturate it with
distilled water, and again scrub the disc surface.
You should now see the water "beading" into droplets.
The disc is wiped off again with toweling. Allow it to air dry, and voilal...
A really clean disc, ready to transfer.
Subsequent dusting of the disc can be done dry with
a red "duster" brush which has a more coarsely distributed
fibre than the black brush.
Now play your cleaned disc. Sounds better, doesnít it!
Most of the bad clicks and pops caused by
dirt will be gone. A sum and difference matrix
allows me to pull out all the unwanted
vertical noise on a lateral recorded disc, or all the lateral
noise on a vertical disc, like an Edison. Now, with
some sharp low frequency filtering it is possible to
get rid of most of the "thump" noises that seem to
plague some early 78's. Adding some careful
equalization can help to reduce the mechanical resonances
of acoustic recordings and vastly improve
the sound of most electrical recordings.
Next, comes the real charm. The heavyweight of
the restoration process is the CEDAR processing
used to remove most of the remaining clicks and
pops crackle and hiss... it is simply a VERY big,
VERY fast, high power computer system,
where dirty audio is fed into the CEDAR boxes and clean
audio comes out. This all happens in real time, that
is, the actual playing time of the music!
A few gouges may remain that will need to be removed by
editing in a digital workstation, but that pretty much
There are many other facets of restoration, such as
the "pitching" of an old recording to ensure that you
are playing it back at the correct speed. Remember,
the music should be heard in the same key as it was
played! EDISON discs, for example, donít play at
78 rpm... they are about a half tone low at that speed
and need to be played at about 80 rpm. On some
early discs, the speed actually varies from the
beginning of a side to the end of the same side,creating
some real challenges for "pitching" of these
records, particularly in a symphonic work where
side joins are necessary. A digital metronome, such
as those made by Seiko, can continuously "play"
actual notes of the musical scale and this is an
invaluable aid to "getting it right".
This has been only a brief outline of what I do to
restore old records for CD producers throughout the
world. Next time you buy a CD of restored old
recordings, and see a credit for "Noise Reduction
Processing by Graham Newton", you'll have a pic-
ture in your mind of just what went into that work.
Surfactant: Kodak Photo-Flo 200,
Catalog No. 146-4502 (4 fl ounces - 118 ml, cost about $5.00).
Available at photo stores with darkroom supplies
Measuring cup: 1 fluid ounce (30 ml)
(available at most pharmacies, cost under $1.00)
Velvet Brushes: Lagniappe Chemicals Ltd.
P.O. Box 37066
St. Louis, Missouri 63141 U.S.A.