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Re: [ARSCLIST] (Fwd) [ARSCLIST] Fwd: Recording Speed
From: Doug Pomeroy <pomeroyaudio@xxxxxxx>
> Thanks Mike.
> I was most confused by George's reference to "the counter", which
> appeared with no explanation that I could find.
It was hidden away a few sentences earlier, at the end of the second
sentence of the part I'm reprinting below.
> > The frequency of the calibration track? It was calculated to be
> > 10 times the rpm of the turntable, in other words, at 78 rpm it
> > gave out 780 Hz, suitable for a frequency counter. In use of the
> > tape as a secondary master, the content could be de-chipmunked
> > by changing the speed of the tape recorder, and the tape rewound
> > to the calibration track, which was measured by the counter and
> > would give the rpm of the original record at the de-chipmunked speed.
> It is much simpler than I thought. Doug
I believe as turntables with internal speed counters became more common,
George backed away from mass producing the little calibration discs, but
now more than ever with digitization of recordings being made without
documentation of rotational speed, this would be a quick and easy way to
supply a notation of rotational speed in just one extra step. If all
records had been made with a reference tone like the Seresate records,
things would be so much easier!
While we are on the subject of using known frequency tones to determine
speed, the ARSC presentation of the Early Sounds project explained that
Leon Scott's Phonautograph continuously recorded a tuning fork tone
alongside of the sound, which now enables the constant speed playback of
these hand-driven pre-tinfoil recordings. This is now called the "Pilot
Tone" system, and is still used to synchronize sproketless-analogue tape
sound with motion picture film. I don't think this has ever been
discussed, but not only did Leon Scott apparently invent sound
recording, he also apparently invented the Pilot Tone speed resolution
Mike Biel mbiel@xxxxxxxxx
> Date: Mon, 22 Jun 2009 11:23:26 -0700
> From: Michael Biel <mbiel@xxxxxxxxx>
> Subject: Re: (Fwd) [ARSCLIST] Fwd: Recording Speed
> I understand what George is saying partially because I've seen him
> do it and I am lucky enough to have one of his calibration discs.
> In case Doug and others still do not understand it, Doug's snip
> cut out the important info and left in material that has no
> meaning without the snipped part.
> In 1982 George commissioned a 7-inch pressing made of a 450 Hz.
> tone cut at 45.0 RPM. That disc can be played at any RPM and a frequency
> counter will show a reading that is 10 times that RPM. (Play it at 73.7 RPM
> and it shows 737.0 Hz. 78.26 shows 782.6 Hz. Etc.) If you have a
> frequency counter handy, you can find what rotational speed you are using. BUT,
> if you include a few seconds of that calibration disc played on the
> same turntable at the time of your transfer of the record you are
> working on, then later on that frequency can be read with a counter and at any
> time you can establish the rotational speed you used. It's like an audible
> strobe disc that has the unique ability to be recorded, and it is as
> accurate as your frequency counter is. Sure, you could use a normal
> test disc of, say, a 1000 Hz. tone, but George's disc is more directly
> readable without using math to have to determine percentage of 1000
> Hz. whatever tone you used.
> Mike Biel mbiel@xxxxxxxxx