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Here is the earliest reference that I have ever seen to Scotch (3M) brand magnetic recording tape. I found it in the October 1947 issue of Radio-Television News magazine.
Craig
Craig
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Last edited by Craig Maier; 05-05-2019, 04:28 PM."Who put orange juice in my orange juice?" - - - William Claude Dukenfield -
I maybe wrong ...from memory DW in Europe were using reel to reel about 1936 please correct if wrong ... I am getting old...????. -
From what I understand, recording on tape was invented during WWII by German scientists and engineers. Scotch and the other brands of magnetic tape were developed primarily by GIs who had captured German radio stations and had samples of the tape and a few of their recorders.Dan McDonaldComment
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Nice ad, though. Also, it's interesting that it's being compared to the competition, which means there were several out already by '47.
Sound is falling off by 2500Hz?
They also suggest it's easy to edit by just using Scotch tape!Dan McDonaldComment
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Magnetic Tape was being used in Europe prior to its use in the United States. I believe that the name of the company who made the German machines was Magnetophon (or something like that). The big "breakthrough" was the use of AC Bias added to the audio signal, which provided full use of the B-H curve of the recording media as opposed to only half of that curve as would have been the case with DC bias. This feature extended the dynamic range of magnetic tape recordings by 6 dB.
Craig
ps - not sure if it's fact or lore, but the invention of AC bias was supposedly an accident. The DC regulator tube in a DC bias machine became un-stable and started to oscillate, unknown to its users. They just noticed better recordings. Upon investigation, they found it oscillating above the audio spectrum.Last edited by Craig Maier; 05-27-2014, 02:39 PM."Who put orange juice in my orange juice?" - - - William Claude DukenfieldComment
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Yes, it was magnetophon. The AC bias was introduced by the Nazis and used in radio stations during the war to broadcast Hitler's speeches. I should have said the bias was the big development. The tape recording before that time was apparently pretty poor. I don't know if they had other innovations or not. There was also a tape recording that used steel threads or something similar during the 1920s, so that could have been what Murray is thinking of.Dan McDonaldComment
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Well, there are three possibilities as it pertains to bias and magnetic media.
1. No Bias: (extreme non-linearity which would produce significant distortion because the B-H curve is not only non-linear but also hysteritic through zero-crossing*).
2. DC Bias: (low distortion because the non-linear, zero crossover portion of the B-H curve is avoided, but the dynamic range is limited)
3. AC Bias: (low distoration plus wider dynamic range because both halves of the B-H curve are utilized).
Craig
*Remanence (or Retentivity) of magnetic materials produces a magnetic memory effect which persists after the removal of an applied magnetic signal, even if said signal becomes zero in value. With alternating current signals, this "loss" must be overcome each cycle of the desired audio output, unless this section of the B-H curve is avoided in some manner.Last edited by Craig Maier; 05-27-2014, 03:07 PM."Who put orange juice in my orange juice?" - - - William Claude DukenfieldComment
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John Herbert Orr, one of the soldiers who captured a Nazi radio station, said that the Allies were perplexed at first because they could pick p broadcasts of Hitler giving different speeches at different points, all over Germany, and that clued the Allies in to some sort of new recording technique or technology. He and a group of others were given the job of capturing a radio station and its equipment. It took them quite a while because the Germans would blow up the station whenever they had to abandon one. Finally, they captured one towards the end of the war, with a number of recorders and reels of tape. A lot of the guys in that unit came back and built careers around it.
Orr said he tried and tried to reproduce the tape and finally went back to Germany to track down the scientists who knew the formula. Finally found one. He brought back the formula and the result was "Irish" tape, later Ampex tape.Dan McDonaldComment
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I remember "Irish" audio-tape from my childhood years (circa 1957). We had some of that tape that my dad used with a "Crestwood, (by Daystrom)" tape deck that used "Brush" brand tape heads. I remember that (recording made from his EICO FM mono tuner) sounded very good - - - and children (as I was at that time) really can tell the diffrerence with these things. So, I would say that tape recording was absolutely perfected by the mid 1950s and that "Irish" brand tape worked just fine.
Craig"Who put orange juice in my orange juice?" - - - William Claude DukenfieldComment
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The 3 M company's improvement was to be able to coat the plastic with the magnetic particles. The company used their knowledge of paint technology to do this. As far as I can tell, 3M was the first to produce mag tape with a plastic base.
The AC bias/recording was discovered first in the US ...forgotten, then re discovered in Germany.
In the radio museum in St Louis park (Minnesota) I saw and heard a recording of Bing Crosby played back on a captured German tape player from WW2. The player had been "reverse engineered" to understand the technology and then returned to operating condition. As you might expect, the recording had some "drop outs" but sounded good.
MarcComment
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