I need question asnswered about vinyl highest frequency ever

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3db
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I need question asnswered about vinyl highest frequency ever

Post: # 27323Unread post 3db
Mon Sep 30, 2013 7:51 pm

Hello

I'm new to this site with little or no knowledge of pressing vinyl. I vaguely remembered reading on a web site where someone in a University had managed to record a 70KHz signal onto vinyl. Is this achievable? Did I misread that site or remember it all wrong? :oops:

Is this guy's math correct about vinyl?

http://vincentranceostberg.myknet.org/

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EmAtChapterV
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Re: I need question asnswered about vinyl highest frequency

Post: # 27324Unread post EmAtChapterV
Mon Sep 30, 2013 9:10 pm

3db wrote:Hello

I'm new to this site with little or no knowledge of pressing vinyl. I vaguely remembered reading on a web site where someone in a University had managed to record a 70KHz signal onto vinyl. Is this achievable? Did I misread that site or remember it all wrong? :oops:

Is this guy's math correct about vinyl?

http://vincentranceostberg.myknet.org/
This is a big theoretical can of worms. You'd be getting into hypothetical frictionless, massless, infinitely-rigid two-dimensional playback styli on a likewise frictionless, infinitely-rigid record. From a practical standpoint, and thinking in mono to keep the mathematics simple, any deviation in the groove can't exceed 45 degrees from parallel, or the back edge of the cutting stylus wipes out what the front edge just cut. Less than that, it becomes less a question of "how high a frequency" and more "how loud a signal at how high a frequency". And at some point the granularity of the record surface is going to exceed this.

I question how much of the Supertramp example is really what's on the record, and how much is harmonic distortion. Bells are all transients and notoriously difficult to track correctly. Surely there's been a high-definition digital audio release of Crime Of The Century that one could A/B compare against a Mobile Fidelity audiophile LP pressing?

In my personal experience, the highest sustained frequencies I've seen deliberately cut to record are courtesy of muted trumpets - 25 to 30 kHz. And as for accidentally, I've had a bad batch of NOS lacquers plus incorrect stylus heat lead to squealing at the edge of a record that was strictly circumferential-distance-based, not velocity-based... and only audible at 16 2/3 rpm, even when cut at 78. So that'd be a wavering 40 to 45 kHz tone at the edge of a 12-inch.

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tragwag
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Re: I need question asnswered about vinyl highest frequency

Post: # 27332Unread post tragwag
Wed Oct 02, 2013 10:42 am

the CD4 system for quad records probably cut the highest frequency ever.
they used an ultrasonic carrier signal for the encode/decode of the additional 2 channels.
there's a whole host of info on it in the "Basic Disc Mastering" vol 2 by Larry Boden
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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boogievan
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Re: I need question asnswered about vinyl highest frequency

Post: # 27586Unread post boogievan
Mon Nov 04, 2013 9:04 pm

The CD4 signals are encoded with a pilot tone and occupy the zone from 20k - 45 kHz.

Cedric Bastiaan suggested that a pickup could play back 100 kHz from a conventional disc, but that for practical levels, a much lower limit must be set. 0: "can you hear me now?"

According the the AES Anthology of Disc Recording, video can be cut to disc. Baird cut motion picture to disc in 1927 @ ~ 78 rpm, but it only had a 5 kHz bandwidth with 12.5 fps. Probably not worth watching, but pretty cool, just the same. By using frequency modulation and an extremely small stylus tip and a platter velocity of 1800 rpm, television discs can be cut with a an FM video signal frequency of 2.5 MHz for ~1000 seconds (i.e., > 16 minutes) on a 12" disc. Groove width is 0.3 mils across the top. The signals (both visible and heard) are picked up by pressure transducers, rather than groove tracers. Not vinyl, either. But a gramophone disc, just the same. The table doesn't turn for these more advanced video sound sheets. The plastic discs are spun by a center holding motor and an air cushion separates the disc from the table.



- boogie

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