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ARSCLIST  November 2009

ARSCLIST November 2009

Subject:

Re: power line frequency

From:

"Michael H. Gray" <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Wed, 4 Nov 2009 06:47:24 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (220 lines)

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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