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From: Patent Tactics, George Brock-Nannestad Hello, from time to time this crops up on ARSCLIST (although I can only locate April 2004 at the moment), because it is highly relevant, both for recording and reproduction done with synchronous motor drive and when using stroboscopes. We are now so fortunate that we have a reasonable certainty of having either 50Hz or 60Hz (not to mention 400 Hz in aircraft), but that was very far from the real world, say from the 1920s and until ca. 1965. I have a fairly good impression of what went on in the US and in the UK (and in central Copenhagen, Denmark, they had DC until 1962!). Ca. 1980 a Danish record collector who had started late in academia, studying the subject of contemporary history, decided to write his thesis for B.Sc. on historians' problems in using sound recordings as historical sources. His name was E. B. Mortensen, in the 1970s a frequent contributor to Talking Machine Review, and his thesis was huge. It was a rambling discussion based on a lot of misunderstood acoustics, but it impressed immensely his non- technical history-based supervisors. He took innumerable measurements and made innumerable calculations that were quite misleading, and he used his ears. He purported that most of the 78s we listen to were really recorded at 75 rpm. He discovered that Hitler sounded much better if the speed of his recordings were reduced by 10%; the speech became much less hysterical and probably more threatening, cajoling, etc. Without any source he claimed that the Germans had reduced their power line frequency from 1935-1944 to 47.3 Hz to save power, and that consequently, when we reproduce at 78 rpm we get an erroneous result. I was given a copy of the thesis by someone who wanted an independent review. I thought the conclusions on Germany were utter nonsense, but how do you disprove such a statement? I worked my way through volumes of the foremost German electrotechnical journal, Elektrotechnische Zeitschrift, the publication of which petered out in 1944, due to shortages and the fact that the pages were quickly filling up with obituaries and death notices. Nowhere did I find anything that could prove or disprove his statement, and anyway, all synchronous clocks would run slow. It was counter-intutitive to a technician, because if heavy machinery needed more power at a lower speed it would simply draw a higher current, and the real saving only occurred during the actual run-down from 50 Hz to 40-something Hz, which could be termed a one-time flywheel effect. I did find papers on the instability of frequency and slow regulation of hydroelectric plants, but I also found the frequency- stabilised converters used for film cameras. Apparently no problems in the professional sector. As Allan Koenigsberg said a short while ago, "How does one prove a negative?" Now, 26 years later I am finding material that seems to indicate that there may have been some truth to Mr. Mortensen's assumption: at least during 1944 they did lower the mains frequency to 45 Hz, and indeed it appears that Germany towards the end of the war had been split into two sectors, one using 43 Hz and the other 41 Hz. There is a strange logic to why this would save energy. You may skip the next if it is too detailed. The frequency really only influenced operation of motors: all AC motors would run more slowly. This meant that e.g. rolling mills, overhead cranes, elevators, etc. would have a lower throughput and thereby a lower power consumption. The voltage was maintained, so lights, heating, vacuum cleaners, etc. would not be influenced. The only real problems would be in the iron used as cores: it would be more likely to saturate and hence the efficiency would fall and transformers would risk overheating. The heavy electrical industry had already optimised the balance of copper and soft iron, and that was for the specified frequency. By the way, house wiring was made with iron wire and small transformers used zinc wire in the last days of the Reich. Now, there are still a lot of open questions here: was any recording and reproduction done at all at mains synchronous speed at that time? And what was the timeframe: Hitler's speeches had been recorded from about 1932, and surely they could not suffer from this phenomenon before the terrible shortages set in. But I am certainly no longer cocksure. But, as I have said on this list before, one of the German broadcasting houses had a quartz- controlled power line installed for their tape recorders and gramophones in the 1950s. Perhaps not to re-live life's complications. I have also recently found via the website: http://vwgc.org.au/VWGCGramNotes.htm that Western Australia had 40 Hz until 1958, and they show a 40 Hz 78rpm stroboscope. The BBC was aware that there might be variations in the mains frequency, and on: http://www.btinternet.com/~roger.beckwith/bh/grams/grams_4.htm you may find calibration discs and a stroboscope "For use when mains frequency at the time of recording differs from that at reproduction". In reality it was no more than 2 Hz either way, and the circles were marked in difference frequency, rather than rpm. The central German broadcast archives had actually informed Mr. Mortensen that the recordings of the German radio stations were marked on the label with the mains frequency! But he obviously did not believe them. The story continues. I would not be surprised to learn that northern Italian records were cut with machines run off 14 Hz or 16 2/3 Hz, which were in use for traction purposes. Let us see if a type-wri-toon will work here: ;-) - yes, it did. Kind regards, George