Post-War DG recording sheets also had the mains frequency noted, perhaps because power frequency then was still somewhat uncertain.
Mike Gray
----- Original Message -----
From: Michael Biel <[log in to unmask]>
Date: Tuesday, November 3, 2009 7:53 pm
Subject: Re: [ARSCLIST] power line frequency
> The change in electrical power in Germany would not affect the
> recordings of Hitler's speeches made here in the U.S. and in other
> countries. I have some complete speeches I recorded directly off the
> discs recorded by CBS in Philadelphia and NBC in Chicago, and excerpts
> from many other albums. What about all those classical recordings
> recorded on disc and tape in Germany during those years? They also
> would be off-speed if Hitler is off-speed. It is quite true that many
> 78s were really recorded at 75 and 76, but this dates back into the
> acoustical era when almost all recording machines were spring or
> fallingweight driven. Many companies continued to use the falling
> weightturntables into the 30s. But there is one more factor. ALL
> of these
> mechanical machines had their speed controlled by centrifugal
> governors,and many electrical motors also were likewise
> controlled. The motors
> were set to run fast and would then be reduced by the governor. If
> governor control was used, mains voltage and frequency would have no
> effect, even if it varied during the recording.
>
>
> Mike Biel [log in to unmask]
>
>
> -------- Original Message --------
> Subject: [ARSCLIST] power line frequency
> From: George Brock-Nannestad <[log in to unmask]>
> Date: Tue, November 03, 2009 7:09 pm
> To: [log in to unmask]
>
> From: Patent Tactics, George Brock-Nannestad
>
> Hello,
>
> from time to time this crops up on ARSCLIST (although I can only
> locateApril
> 2004 at the moment), because it is highly relevant, both for
> recordingand
> 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
> fairlygood
> 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
> hystericaland
> probably more threatening, cajoling, etc. Without any source he
> claimedthat
> 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,
> "Howdoes
> 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
> during1944
> 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
> motorswould
> 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
>
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