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What is the effective bit rate of vinyl?, LP recording
klockworks
post Jul 14 2005, 07:27
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I would like to record my vinyl and would like to know what the effective bit rate is of a vinyl (LP) recording? Anyone? Or is this a silly question?


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Axon
post Jul 14 2005, 18:47
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The measured response of vinyl has in some cases measured at 38Khz. Some quadrophonic encodings used modulation with an ultrasonic carrier to store the surround information, and those records were certainly not unplayable after the 2nd spin. There also might be a use for ultrasonic recording to give pattern matching of pops/scratches but I'm not sure if those actually extend into ultrasonic.

That said, vinyl does degrade considerably in the high end over time, although the effect is lessened with proper cartridge/tonearm care. Also the SNR varies considerably over the frequency spectrum. And of course there's the high-end rolloff on the inner grooves due to lower linear velocity, which also reduces bandwidth. So all things considered, a proper application of Shannon's Theorem would in fact be quite complicated.
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Woodinville
post Jul 14 2005, 19:03
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QUOTE (Axon @ Jul 14 2005, 09:47 AM)
There also might be a use for ultrasonic recording to give pattern matching of pops/scratches but I'm not sure if those actually extend into ultrasonic.
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This is fairly useful, if you can afford to sample at a high rate, detect the impulse noise errors (they tend to have a much wider bandwidth than real signal), and then downsample after you do your nonlinear processing.

But there is no point in long-term storage like that, unless you think you might have a better de-clicking algorithm some time later.


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