Corey Bailey
Audio Engineering
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 (and it will), 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. 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. Light fishing leader or sewing thread works well as a replacement. Use about 6 feet. When replacing the leader, I will often tie a loop around the supply spool to keep the leader from un-threading. I have experimented with methods of cleaning the record-play 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 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 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 has been 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. This works however, 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). The bare head used high value resistors to create a high impedance input because a vacuum tube preamp was used. Where you take the audio signal, will determine the type of preamp to be used. 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 generally 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. Most 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 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 but they usually ended up in disaster. So now, I just ‘let it rip’ and try to avoid tangles. Return to TOP of page © Corey Bailey Audio Engineering
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