From: Patent Tactics, George Brock-Nannestad
Hi Gary,
unfortunately my Aida Favia-Artsay stroboscopes are out of reach at the moment,
but typical of such stroboscopes is that they have a number of concentric
rings, the next one out having one more marking on the ring. The rpms (at a
given mains frequency) are given for each ring. There is a nifty formula for
calculating the number of markings you need for a given frequency to get close
to a target rpm, but I am not bringing it here. If I remember correctly, with
77 markings you get 77.92 rpm when a 100 Hz light flashes on that ring and it
is stationary. The 100 comes from the fact that with AC there are two flashes
for each complete cycle -- the incandescent wire does not distinguish between
the directions the current has at any one instant. But this means that the rpm
of the neighbouring rings have rpms that are 1.3 % (1/77) higher and lower.
I cannot find fault with your calculation, the 76.6 rpm Caruso (intended) will
be 0.42% or 1/14 of a semitone sharp (give or take) when using the closest
stationary ring on the 50 Hz stroboscope.
Even though I am very happy with my digital rpm-counter I think that the KAB
strobe is ingenious, because it will permit observing cyclic errors in the rpm
(sudden jumps in the stationary pattern), whereas my counter only reads out
what the average rpm is for each revolution. I did not know the KAB strobe set
but I shall probably buy it for precisely this reason. Thank you for the
reference!
I have a 78 rpm stroboscope that you are supposed to look at through the
vibrating prongs of an a=435 Hz tuning fork. With such a high frequency you get
a much better approximation to 78.
I am reminded of a yet different approach. In 1982 I made with public funding a
calibration record, a 7" coarse groove vinyl record. One side was for lateral,
the other for vertical modulation. On it were several tracks, but the most
important were the outer tracks. They contained a frequency that was 10x the
rpm the record was played at. So, for 78 rpm you could measure a frequency of
780 Hz (and for 33˝ you would read 335). Seeing that most digital voltmeters
these days also measure frequency, it is quite simple to use. Then you could do
with the cheapest hp Frequency Counter.
The remaining tracks contained the standard pitches a=440 and a=435 at various
rpms, and they permitted the use of my Korg Tuning Standard (their first analog
model) to measure the deviation in cents. I have used a Korg since 1982, but
for certain pitchings the oldest is still the best.
As an aside, this record was advertised (with a good technical description) in
international sound archive circles, and 2 (two) archives showed an interest. I
sent them test pressings for free, and the record was never produced. But my
few remaining test pressings will last my lifetime.
Best wishes,
George
--------------------------------------
From: "Gary A. Galo" <[log in to unmask]>
To: [log in to unmask]
Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
Date sent: Thu, 27 Apr 2017 19:40:10 +0000
> Hi George,
>
> Following Aida Favia-Artsay, the difference between 76.60 (60Hz) and 76.92
> (50Hz) is 0.42%. This is an unacceptable pitching error. Are you telling me
> that every 76.6-rpm Caruso record pitched using her 50 Hz strobe will be
0.42%
> off?
>
> It would seem that, for turntables lacking a digital readout, a sensible
> solution is KAB's Speed Strobe:
>
> http://www.kabusa.com/strobe.htm
>
> The Speed Strobe comes with its own LED lamp, which is illuminated with a
> quartz-locked AC signal. Therefore, it is not dependent on the power line
> frequency, and will work equally well in 60 Hz and 50 Hz countries.
>
> Gary
>
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of George Brock-Nannestad
> Sent: Wednesday, April 26, 2017 7:24 PM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
>
> From: Patent Tactics, George Brock-Nannestad
>
>
> Hi Gary,
>
> once you have a digitally controlled turntable, what you read on the display
> is what you get in the way of rpm. It is confusing that the display
expresses
> this as a percentage of the "central" speed (0%). It is actually better with
> my portable digital rpm-counter: I put a sliver of retro-reflective tape on
> the rim of the turntable, aim the lightspot of the counter at the rim, and
the
> display tells me the precise rpm. No need to calculate a percentage
> deviation.
>
> Stroboscopes merely provide approximations to 78.00 rpm -- with 60 Hz light
> you get a stationary ring image at 78.26 as the closest approximation. With
50
> Hz light you get a stationary ring image at 77.92 rpm. Those who have
> practiced long will be able to judge the slow backwards drift of the 78.26
> ring at 60 cycles per second (Hz) that is required to get even closer to
> 78.00. Similarly, there is a slight forwards drift of the 77.92 ring for 50
> cycles if you want spot-on 78.00.
>
> If you aim for the precise speed of the old stroboscopes when using your
> digitally controlled turntable you will need to speed up the turntable (60
> Hz
> basis) or slow it down (50 Hz basis).
>
> The most universal stroboscopes were strips with bar indications that were
> rolled up like a tape-measure (cylindrical) so that only the required number
> of bars were visible. You put the cylinder on the rotating record, centered
it
> and adjusted the speed until the chosen number of bars was stationary.
>
> For the above reasons I do not quite understand your precise question.
> However, I hope to have solved the underlying problem.
>
> Now, you do say that 1 minute is 1 minute, and that is where the difference
in
> the US synchronous speed of 78.26 and the European speed of 77.92 really
> shows
> itself: in broadcast planning. The US recording will be reproduced too
slowly
> in Europe and will overrun its intended duration by several seconds. That is
> in practice the only way to notice it -- it can generally not be heard at
> all.
>
> Best,
>
>
> George
>
> ----------------------------------
> From: "Gary A. Galo" <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
> Date sent: Wed, 26 Apr 2017 22:08:13 +0000
>
> > Hi George,
> >
> > This issue of speed at 60 Hz vs 50 Hz has long been source of
> > confusion because, on the face of it, the duration of 1 minute is the
> > same everywhere, and a given number of revolutions during that time
> > period should be the same regardless of the line frequency. Here's a
> > hypothetical question: Let's say we have a Technics
> > SP-15 turntable, which is digitally-controlled and has regulated,
> > switching-mode power supplies. As such, line frequency and voltage are
> > irrelevant to its operation. If this turntable is operated in a
> > country where the mains frequency is 50 Hz, are you suggesting that
> > achieving 78.26-rpm requires setting this turntable's digital readout to
> -0.4 % to achieve 77.92?
> >
> > I pose this question because I know a lot of people were confused,
> > decades ago, by the two strobes that Aida included with her Caruso
> > book. Many still are.
> >
> > Best,
> > Gary
> >
> > ____________________________
> >
> > Gary Galo
> > Audio Engineer Emeritus
> > The Crane School of Music
> > SUNY at Potsdam, NY 13676
> >
> > "Great art presupposes the alert mind of the educated listener."
> > Arnold Schoenberg
> >
> > "A true artist doesn't want to be admired, he wants to be believed."
> > Igor Markevitch
> >
> >
> > -----Original Message-----
> > From: Association for Recorded Sound Discussion List
> > [mailto:[log in to unmask]] On Behalf Of George Brock-Nannestad
> > Sent: Monday, April 24, 2017 6:43 PM
> > To: [log in to unmask]
> > Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
> >
> > From: Patent Tactics, George Brock-Nannestad
> >
> >
> >
> > Hello,
> >
> > all very US-centered, isn't it? The 78.26 comes from a certain number
> > of poles in a synchronous motor combined with simple ratios in the
> > gearbox that changes the rpm from the motor to the target rpm for the
> > turntable. But it is only this figure at 60 Hz mains frequency. If you
> > had a slow-speed synchronous motor run off 60 Hz the closest to 78.00
> > is 78.26 rpm. If you use a stroboscope for 60 Hz under a 120 Hz light
> > (goes for fluorescent or low-power incandescent lamps off the mains),
> > you can only get a stationary ring at 78.26.
> >
> > In the not insignificant parts of the world where they use 50 Hz as
> > the mains frequency, the corresponding figure would be 77.92 rpm. You
> > need a different stroboscope for this and also the slow-speed
> > synchronous motor would have a different number of poles. Aida
> > Favia-Artsay knew, and her Caruso stroboscopes came in both varieties.
> >
> > The Victor Talking Machine Company is on record in the acoustic period
> > as specifying 76 rpm for recording and 78 rpm for reproduction of the
> > recording obtained. Some of their customers obviously did not have
> > absolute pitch. In the acoustic period of the Gramophone Company, the
> > speed was checked every morning by means of a piece of cigarette paper
> > under the wax while cutting and counting the revolutions for a minute.
They
> preferred 78 rpm!
> >
> > In the United Kingdom, the Old Philharmonic Pitch (which corresponded
> > to an a4 of 452 Hz (give or take a few) survived in the military bands
> > until ca. 1926, when they also changed to the New Philharmonic Pitch
> > at 439 Hz. If you hear Nellie Melba sing accompanied by the Band of
> > the Coldstream Guards in 1905 with the key indicated, you can pitch it
> > absolutely correctly when you play
> > it: they used the Old Philharmonic Pitch. Columbia recorded a lot of
> > military bands, and they abandoned the 80 rpm speed for 78 rpm at
> > around the same time the bands changed tuning. The interesting thing
> > is that the fraction 78/80 is very nearly the same as the fraction
> > 439/452, in other words if you played a Columbia band record in 1932
> > you would not know whether it was an early recording slowed down to 78
> > or whether it was actually a new recording with the new pitch and the
> > new speed. This is what I habitually in my workshops call "the dialectic
> triangle:
> > speed, key, and standard pitch".
> >
> > I rarely comment these days, but this issue is very important.
> >
> > Best wishes,
> >
> >
> > George
> >
> > ---------------------------------------------
> >
> >
> > > 78.26 did not become a standard speed until electric motors were
> > > used in cutter and playback turntables. In the acoustic era, 78
> > > usually meant
> > 78.00.
> > > But, if you´re using a modern turntable like, say, a Technics SP-15,
> > > 78 actually is 78.26, and the percentage of change must be
> > > calculated from that.
> > >
> > > Gary
> > >
> > > ____________________________
> > >
> > > Gary Galo
> > > Audio Engineer Emeritus
> > > The Crane School of Music
> > > SUNY at Potsdam, NY 13676
> > >
> > > "Great art presupposes the alert mind of the educated listener."
> > > Arnold Schoenberg
> > >
> > > "A true artist doesn't want to be admired, he wants to be believed."
> > > Igor Markevitch
> > >
> > > From: DAVID BURNHAM [mailto:[log in to unmask]]
> > > Sent: Monday, April 24, 2017 6:05 PM
> > > To: Gary A. Galo
> > > Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
> > >
> > > That's fine, but the standard speed for 78s IS 78.26; I don't know
> > > if 80RPM records included a fraction. LPs, of course are always
> > > based on
> > > 33 1/3 RPM, so there would be no reason to relate anything to 33.00
> > > RPM. I'm sure the original question was searching for a corrective
> > > adjustment to adapt from standard 78 to Columbia's 80 RPM, but
> > > that's only a
> > guess.
> > >
> > > db
> > >
> > >
> > >
> > > On Monday, April 24, 2017 5:56 PM, Gary A. Galo
> > > <[log in to unmask]<mailto:[log in to unmask]>> wrote:
> > >
> > > I specifically said 78.00 in my reply. I assumed that if you meant
> > > 78.26, you would have said so.
> > >
> > > Gary
> > >
> > >
> > > -----Original Message-----
> > > From: Association for Recorded Sound Discussion List
> > > [mailto:[log in to unmask]<mailto:[log in to unmask]>]
> > > On Behalf Of DAVID BURNHAM
> > > Sent: Monday, April 24, 2017 4:44 PM
> > > To: [log in to unmask]<mailto:[log in to unmask]>
> > > Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
> > >
> > > Are you basing that on 78.00 RPM or 78.26 RPM?
> > > Not challenging you just a question.
> > > db
> > >
> > > On Monday, April 24, 2017 4:18 PM, Gary A. Galo
> > > <[log in to unmask]<mailto:[log in to unmask]>> wrote:
> > >
> > >
> > > A quarter tone is 3%, a half tone is 6%, and a whole tone is 12%.
> > > So, the difference between 78.00 and 80 is just a hair under a
> > > quarter tone. A quarter tone would be 80.34; a half tone is 82.68..
> > >
> > > Gary
> > >
> > > ____________________________
> > >
> > > Gary Galo
> > > Audio Engineer Emeritus
> > > The Crane School of Music
> > > SUNY at Potsdam, NY 13676
> > >
> > > "Great art presupposes the alert mind of the educated listener."
> > > Arnold Schoenberg
> > >
> > > "A true artist doesn't want to be admired, he wants to be believed."
> > > Igor Markevitch
> > >
> > > -----Original Message-----
> > > From: Association for Recorded Sound Discussion List
> > > [mailto:[log in to unmask]<mailto:[log in to unmask]>]
> > > On Behalf Of James Roth
> > > Sent: Monday, April 24, 2017 3:31 PM
> > > To: [log in to unmask]<mailto:[log in to unmask]>
> > > Subject: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
> > >
> > > Hello everybody,
> > >
> > > Can anyone tell me how many half-tones up from 78 rpm to 80 rpm?
> > >
> > > Thanks.
> > > Ben Roth
> > >
> > >
> > >
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