Corey Bailey
Audio Engineering
USEFUL INFORMATION
Wire recordings have an unknown life expectancy. I have played wire
recordings made in the 1940’s and they played just fine. I can’t say the
same for audio tapes from the mid 1970’s to the mid 1990’s. So, while wire
recordings are indeed magnetic recordings, the lifespan appears to differ
greatly from those recordings made on audio tape.
Playing a wire recording can be a daunting task but, if done carefully, one
can extract the contents. The wire is generally made of stainless steel and
is very fine, averaging approximately 0.005 inches, (about 0.012mm) or
approximately the diameter of a strand of thick human hair. The average
speed was quite fast, about 24 inches per second (approximately, 61 cm/s).
Wire recorders were used commercially for various tasks and popular with
consumers as well, until audio tape came along and replaced the
technology. The two most popular types of wire recorders are those that
used a spool having a small hole (about ¼” in Dia.) to be used on a
corresponding shaft and those that used a spool with a much wider center
hole (about 1-3/8” in Dia.). The later being the consumer model which is
more common. Both types typically use a record/play and a erase head.
The heads on most wire recorders are built into one assembly.
Because the wire is so thin, tangles and breakage are a real problem.
When the wire broke (Murphy’s Law), I used to splice it by soldering about
a 1/4” overlap which would be hardly noticed because of the play speed,
even if I had to trim some wire to make a clean splice which, I usually did.
However, that method is very tedious, time consuming and requires Silver
Solder so, I defaulted to the standard method of tying a square knot, which
is still tedious. Knots and other anomalies seem to pass through the head
just fine.
Because the wire is so old, the factory leader may have to be replaced.
Fishing line or thick sewing thread works well as a replacement. Make sure
that it won’t get caught in the record/playback head. I will often tie a loop of
leader around the supply spool to keep the leader from un-threading.
I have experimented with methods of cleaning the record/playback head.
Webster Chicago’s owners manual recommends using a brush with the
bristles soaked in Trichloroethylene. Obviously, the owner’s manual was
written in the 1940’s. I’ve used a fine bristled brush, with the bristles
trimmed to about ¾,” soaked in denatured alcohol and it seemed to work.
The method that I currently use is a dedicated reel of thick sewing thread
that I will soak with denatured alcohol and play for about 30 seconds. The
cleaning spool also contains a couple of segments of recording wire that
I’ve pre-recorded with alignment tones which, I use for level setting.
Before playing a wire, it’s best to advance the mechanism by hand in order
to line up the head with the spool of wire. Observe how the wire spool will
unwind so that the head travel will match the way the wire un-spools. You
can do this by rotating the take-up spool on most machines. The available
user manuals recommend starting the head at the top of the travel. While
that works, I’ve found that matching the position and direction of travel of
the wire to be the best method.
Fidelity is poor by today’s standards, averaging from about 50Hz to 5kHz.
You may notice an unusual amount of hum that is baked into many wire
recordings. This is mainly due to the drive motor being poorly isolated,
mechanical operation of the machine while recording and and the
electronic technology of the time.
I learned right away to take the play head direct into a modern microphone
preamp which produces much better fidelity. You will need a microphone
preamp with plenty of gain (more than 70 dB). Where you take the audio
signal, will determine the type of preamp to be used. Originally, the bare
head used high value resistors to create a high impedance input because
of a vacuum tube preamp.
Equalization (EQ) should not be a problem. As far as I can tell, wire
recorders didn’t use any EQ. However, use your ears to get the best sound.
I generally transfer flat, then apply any EQ, editing, etc. on a copy of the
file. Many of the consumer recordings that I transferred were recorded by
holding a microphone up to a speaker which, is not the best method. Plus,
the average person doing the recording was usually unaware of good
microphone techniques. Most wire recorders used a crystal microphone
which has it’s own fidelity issues. That said, I have transferred some wire
recordings that were very well recorded. So, it’s possible to get good
results.
Nearly all wire recorders used mechanical switching for play and rewind.
Rewind is generally scary fast and the tension is often slack. This is where
most of the tangles happen. I have found that applying very light pressure
to the supply reel during rewinding (which was the take-up reel during
playback) will vastly reduce tangles. You can do this by gently laying a
finger on the supply reel. The weight of your finger is usually enough.
Some machines have a turned up edge on the take-up reel that was used
to facilitate threading so you have to watch out.
The wire needs to take the same path during rewind as it did during
playback because the head assembly moves up and down or in and out to
provide an even wind. One would think that head wear would be a problem
but I haven’t noticed a decrease in fidelity over time. At first, I tried a
number of things to avoid the possibility of wearing the play head during
rewind however, they usually ended up in disaster. So now, I just ‘let it rip’
and try to avoid tangles.
When I was in business, I transferred about 50 wire recordings for
customers and I thought that there would be more.
Besides the popularity of dedicated machines, there were a number of
record players adapted as wire recorders so that one could play a record
and play a wire. Some combo units had radios built into them.
Apparently, wire recording was popular as a dictation format and used
aboard aircraft to record military and commercial pilots radio voices (it was
the original black box). Wire was also used in spy recorders because the
spools of wire could be made small.
I only had one wire get so tangled that I couldn't save it. It was during
during the process of rewinding. I was using a finger to control the tension
and the threading slot on the reel grabbed my finger. While I was nursing
my finger, the wire tangled. Although I had to deliver the tangled wire in a
plastic bag, I had already made the transfer, so all was not lost.
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© Corey Bailey Audio Engineering
PLAYING A WIRE RECORDING