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Pye-Rate
Starship Co-Pilot
Joined: 14 Dec 2013
Posts: 625
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 Posted: Sun Jan 17, 2016 8:37 pm Post subject: Very Early Movie Sound |
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1910 duo gramophone for theaters.
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Bud Brewster
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Joined: 14 Dec 2013
Posts: 17105
Location: North Carolina
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| Posted: Sat Mar 05, 2016 9:43 am Post subject: |
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This is a beautiful piece of machinery. Thanks!
I suspect the proximity of the speakers to the record players caused a problem. I know from personal experience that a record player needle and the record it sits on can actually become a microphone, and this causes a sort of "feedback" when the sound from the speakers create sympathetic vibrations in the record itself, so that the needle picks up the noise.
Many years ago I was listening to cassette tape I'd made on my turntable, and during a quite moment in the music I noticed the faint sound of a dog barking in the background on the tape.
I realized that the barking was A.J., my Eskimo Spitz, who had been near the turntable during the recording, and his barking had been picked up by the record and transmitted through the needle to the tape!
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scotpens
Starship Captain
Joined: 19 Sep 2014
Posts: 874
Location: The Left Coast
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| Posted: Sat Mar 05, 2016 12:53 pm Post subject: |
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| Bud Brewster wrote: | | I suspect the proximity of the speakers to the record players caused a problem. I know from personal experience that a record player needle and the record it sits on can actually become a microphone, and this causes a sort of "feedback" when the sound from the speakers create sympathetic vibrations in the record itself, so that the needle picks up the noise. |
Can "feedback" happen without electric amplification? The device in the picture is acoustic, not electric. The "speakers" are just acoustic horns.
Electrical sound recording didn't exist until the mid-1920s. |
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Bud Brewster
Galactic Fleet Admiral (site admin)
Joined: 14 Dec 2013
Posts: 17105
Location: North Carolina
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| Posted: Sat Mar 05, 2016 2:59 pm Post subject: |
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| scotpens wrote: | Can "feedback" happen without electric amplification? The device in the picture is acoustic, not electric. The "speakers" are just acoustic horns.
Electrical sound recording didn't exist until the mid-1920s. |
Actually, feedback can occur with the device above — though it isn't caused in quite the same way as the feedback you get with electric sound recording.
Whenever I was making tapes from my turntable, I actually had to keep the volume below a certain level, or the sound waves would actually cause the needle to jump out of the grooves!
Naturally my dog's barking was not loud enough to do that. But it was loud enough to vibrate the record and send a "copy" of his barking to the tape! The record-and-needle arrangement had actually functioned like a very poor microphone, and it had picked up A.J.'s barking.
Think of it sort of like the old cans-and-sting telephones we made as kids. When we spoke into the can, the bottom of the can transmitted vibrations to the string connected to it, and the string then transmitted the vibrations to the other can. The bottom of that can then functioned as a speaker and reproduced your voice (or a very fuzzy version of it).
The feedback we're all familiar with, of course, happens when a mic is open and the speakers are too close or too loud, so that the sound waves go from the speakers to the mic, which picks them up and then sends an electric signal back to the speakers, which then sends more sounds waves to the mic . . .
You get the idea. 'Round and 'round goes the signals, louder and louder goes the feedback howl.
With the system shown above, the sound waves literally "shake" the record, which then vibrates the needle, which then sends sounds to the speakers, which then shakes the needle . . .
The record and the needle become like a microphone and — Voil??! Feedback. Admittedly it would more accurately be described as "distortion", but it definitely is being caused by sounds being "fed back" into the system.
The flat surface of the record is like the diaphragm inside a microphone. The needle responds to the vibrations of the record when the sound waves hit it, and the vibrating needle then sends signals back to the speakers — just like a mic does when it picks up the noise that the speakers are making.
In other words, the sound made by the speakers is being "fed back" to them by the vibrating record-and-needle that is acting like a crude microphone.
Thus we have "feedback".
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Is there no man on Earth who has the wisdom and innocence of a child?
~ The Space Children (1958)
Last edited by Bud Brewster on Mon Mar 19, 2018 12:19 pm; edited 1 time in total |
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Robert (Butch) Day
Galactic Ambassador
Joined: 19 Sep 2014
Posts: 1437
Location: Arlington, WA USA
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| Posted: Sat Mar 05, 2016 3:35 pm Post subject: |
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These early sound systems were used in the early days just past the "Nickleodeons" when theaters where very small. Like the early Edison phonographs the size of the horns were used to do what little amplification of the sound that there was.
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