quote: Steve Guttag

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I'd say that it would be +/- 0.5fps but again

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quote: David Buckley

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Crystals work the other way up; short term, they are quite stable, but their long term accuracy is poor.

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quote: Chris Markiewicz

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I'm not sure about the acceptable tolerance as such, but I read long ago that the Dolby readers had a certain frame-rate tolerance within which they would correctly read the data stream. Not sure about DTS or SDDS.

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quote: David Buckley

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Tone-wheel Hammond organs are also locked to the mains frequency, and in normal use, folks don't complain about them going out of tune.

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quote: Carsten Kurz

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Quite a few exhibitors in europe followed a bad habit of operating their machines at 25fps in order to squeeze out a few minutes per day

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quote: Martin McCaffery

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I've heard it alleged (by Paul Simon among others) that radio DJ's back in the 45rpm era would do this also to make room for a little bit more advertising.

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quote: Martin McCaffery

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I've heard it alleged (by Paul Simon among others) that radio DJ's back in the 45rpm era would do this also to make room for a little bit more advertising.

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quote: Justin Hamaker

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I wonder how much variation from 24 fps is possible before it is noticed by the viewer.

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I'm guessing that uneven speed, such as from one of those old Bell & Howell
16mm projectors with a flakey mechanical governor, would be more noticeable,
(and annoying) audio-wise, than a projector that ran a frame-or-two off speed,
but at a constant rate. I'll bet most movie goers, unless they had a really good
'ear', probably wouldn't notice if a projector's speed was off by a constant few fr/ps.

Interesting anecdote:
A couple of years ago I was doing a rehearsal with a small orchestra that
was going to be playing with a rare silent film. These guys were professional
'silent film musicians' and did this all the time.

About 10sec into the rehearsal, the stage manger was on the comm-radio
saying that the orchestra leader was asking for me to double check the
projector speed.

The speed was supposed to be 18fr/sec, but I accidentally fat-fingered
19fr/sec when I was punching numbers into the speed controller.
(or maybe it was the other way around)

But whatever... I was pretty impressed that those guys could tell I was just
one friggin' frame-per-second off speed so quickly.
 

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Posted by Steve Guttag (Member # 268) on 02-19-2017, 12:51 PM:
 
Jim, you are so wrong. Even a 1fps variance in a 24/25fps system is quite noticeable in pitch.

In your silent film case, you are talking about over a 5% faster speed. The musicians/conductor are likely using a metronome to ensure that they stay at the right pace. 5% is HUGE to be off.

When I've done silent films, I've had situations were we were down to 2/100ths of a frame per second (depends on the movie and who is orchestrating, really).

In fact, I found that supplying a mere 2-digit readout to be insufficient for sites that were going to be doing silent movies with such accompaniment and would specify 3-digit (tenth of a frame per second readout) in order to be accurate enough. Many times, when they rehearse, they time a passage for how long it should be and where the beats are. So you may be matching another projector's inaccuracy or even a video player and all of what it took to get the image onto that device.

BL&S on some of their road show type events had dubber that only had the time code information on it and a "clock" for the conductor to gauge themselves with to ensure that the musicians were always in time with the movie.

The musicians of the day never had it so good!
 

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Posted by Louis Bornwasser (Member # 3063) on 02-19-2017, 01:22 PM:
 
Our local top 40 station had Gates turntables, 3 speed. 33-45-45+. They turned down the 78 rpm position in a lathe. Two problems: Some songs sounded terrible when up-pitched. The two turntables were not exactly the same speed; I could tell them which turntable they were using.

The biggest problem that those of us with perfect pitch had was that notes moved up to the cracks where no real note existed.
 

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Posted by Scott Norwood (Member # 30) on 02-19-2017, 01:48 PM:
 
When I was in high school (early '90s) some friends and I noticed that the local top-40 station (WXKS-FM) was playing many songs about 1-2% fast. I assume that they were using CDs (or maybe carts) at that point, but the change in pitch from what it should have been was unmistakable for anyone familiar with the songs that they were playing. Did normal people notice? Apparently, not enough to get them to stop doing that. No doubt, a classical station that tried something like that would be flooded with complaints.

I have no idea if they still do this. I don't normally listen to top-40 radio now.
 

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Posted by Randy Stankey (Member # 64) on 02-19-2017, 02:19 PM:
 

quote: Jim Cassedy

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I was doing a rehearsal with a small orchestra that
was going to be playing with a rare silent film. These guys were professional
'silent film musicians' and did this all the time.

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quote: Steve Guttag

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Jim, you are so wrong.

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quote: Randy Stankey

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Wouldn't happen to be I Musici de Montreal, per chance?

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quote: Sam D. Chavez

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d also be a v35 mag sound reel to reel could be annoying because any splices would be heard before being seen and the effect was always jarring especially when running an old print. There coulariation in the speed when the spice hit the Davis loop rollers, also annoying.

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quote: NBC NEWS/Associated Press

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A yearlong experiment with America's electric grid could mess up traffic lights, security systems and some computers — and make plug-in clocks and appliances like programmable coffeemakers run up to 20 minutes fast.

"A lot of people are going to have things break and they're not going to know why," said Demetrios Matsakis, head of the time service department at the U.S. Naval Observatory, one of two official timekeeping agencies in the federal government.

Since 1930, electric clocks have kept time based on the rate of the electrical current that powers them. If the current slips off its usual rate, clocks run a little fast or slow. Power companies now take steps to correct it and keep the frequency of the current — and the time — as precise as possible.

The group that oversees the U.S. power grid is proposing an experiment that would allow more frequency variation than it does now without corrections, according to a company presentation obtained by The Associated Press.

Officials say they want to try this to make the power supply more reliable, save money and reduce what may be needless efforts. The test is tentatively set to start in mid-July, but that could change.

Tweaking the power grid's frequency is expensive and takes a lot of effort, said Joe McClelland, head of electric reliability for the Federal Energy Regulatory Commission.

"Is anyone using the grid to keep track of time?" McClelland said. "Let's see if anyone complains if we eliminate it."

Won't affect GPS or Internet
No one is quite sure what will be affected. This won't change the clocks in cellphones, GPS or even on computers, and it won't have anything to do with official U.S. time or Internet time.

But wall clocks and those on ovens and coffeemakers — anything that flashes "12:00" when it loses power — may be just a bit off every second, and that error can grow with time.

It's not easy figuring what will run fast and what won't. For example, VCRs or DVRs that get their time from cable systems or the Internet probably won't be affected, but those with clocks tied to the electric current will be off a bit, Matsakis said.

This will be an interesting experiment to see how dependent our timekeeping is on the power grid, Matsakis said.

The North American Electric Reliability Corp. runs the nation's interlocking web of transmission lines and power plants. A June 14 company presentation spelled out the potential effects of the change: East Coast clocks may run as much as 20 minutes fast over a year, but West Coast clocks are only likely to be off by 8 minutes. In Texas, it's only an expected speedup of 2 minutes.

Some parts of the grid, like in the East, tend to run faster than others. Errors add up. If the grid averages just over 60 cycles a second, clocks that rely on the grid will gain 14 seconds per day, according to the company's presentation.

Spokeswoman Kimberly Mielcarek said the company is still discussing the test and gauging reactions to its proposal, and may delay the experiment a bit.

Aimed at making grid more reliable
Mielcarek said in an email that the change is about making the grid more reliable and that correcting the frequency for time deviations can cause other unnecessary problems for the grid. She wrote that any problems from the test are only possibilities.

In the future, more use of renewable energy from the sun and wind will mean more variations in frequency on the grid, McClelland said. Solar and wind power can drop off the grid with momentary changes in weather. Correcting those deviations is expensive and requires instant backup power to be always at the ready, he said.

The test makes sense and should not cause too much of a hassle for people, said Jay Apt, a business professor and director of the Electricity Industry Center at Carnegie Mellon University.

But Tom O'Brian, who heads the time and frequency division at the National Institute of Standards and Technology, expects widespread effects.

He said there are alternatives if people have problems from the test: The federal government provides the official time by telephone and on the Internet.

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quote: Sam D. Chavez

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There were plenty of slow running Century with aluminum drive pulleys. I measured one at 21FPS.

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quote:

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Won't affect GPS or Internet
No one is quite sure what will be affected. This won't change the clocks in cellphones, GPS or even on computers, and it won't have anything to do with official U.S. time or Internet time.

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quote:

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Quite a few exhibitors in europe followed a bad habit of operating their machines at 25fps in order to squeeze out a few minutes per day, and obviously, SRD and DTS was able to follow.

I once overheard a couple at an exhibitor conference complaining that this is no longer possible with DCI ;-)

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I doubt that very much. The difference between 25fps and 24fps is 3600 frames over the course of an hour which is 144 seconds at 25fps. So 4.8 minutes over the course of 2 hours. They could accomplish the same thing by running shows 5 minutes closer together or playing one less trailer. And if they ran shows at non-odd times, like 12, 2:30, 5, 7:30, 10, they'd only be saving anything on the last show and that would only be less than 5 minutes. So if they were doing it, it was nonsensical.
 

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Posted by Pete Naples (Member # 761) on 09-26-2017, 04:30 AM:
 
That definitely went on, some circuits here had Kinoton/Phillips with VFD and usually those had a switch somewhere inside which allowed 25fps.

That nearly 5 minutes might mean catching your bus home, or more likely catching last orders at the pub
 

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Posted by Marcel Birgelen (Member # 6801) on 09-26-2017, 05:36 AM:
 

quote: Martin Brooks

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I doubt that very much. The difference between 25fps and 24fps is 3600 frames over the course of an hour which is 144 seconds at 25fps. So 4.8 minutes over the course of 2 hours. They could accomplish the same thing by running shows 5 minutes closer together or playing one less trailer. And if they ran shows at non-odd times, like 12, 2:30, 5, 7:30, 10, they'd only be saving anything on the last show and that would only be less than 5 minutes. So if they were doing it, it was nonsensical.

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Yep, it actually happened and I be damned it didn't happen outside of Europe either.

Maybe Europeans were more used to the higher pitched voices, since most film to PAL and SECAM conversions happened by speeding it up to 25fps. So, they simply compensated for the audience expectations.
 

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Posted by Sascha F. Roll (Member # 9043) on 09-26-2017, 08:56 AM:
 
At the Multiplex I was working 10 years ago all Lenze Frequency Converters in the Ernemann 14s were set to 52Hz...
 

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Posted by Gary A. Hoselton (Member # 3447) on 10-02-2017, 10:03 PM:
 
Last month I changed motor drive belt on 16mm Eiki EX-6000. Program was "The Cheyenne Social Club"(1970). Two weeks later a fellow asked me if I had speeded the show. I hadn't noticed, but opened case and found I'd inadvertently put belt on 50Hz pulleys instead of 60Hz, with 60Hz mains. I am still puzzled that I did not notice change in picture and sound.
 

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