CDs with emphasis or preemphasis
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edwinaviles

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Hello.
Upon reading CD player and DAC reviews in 'Stereophile' I read the measurement sections regularly.
John Atkinson performs a measurement that shows "frequency response at -12dBFS with 44.1kHz sampling" with and without emphasis in his figures.
He mentions in the July 2002 issue on page 92, middle column, middle paragraph, that the Musical Fidelity A324 DAC doesn't apply the appropriate deemphasis for the small number of preemphasized CDs.

WHAT DOES THAT MEAN, PLEASE?

I am so lost on this issue and it isn't an easy thing to look up.

Thanks.
 
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thomas

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Emphasis was used to bump up the treble on recordings, so when it is played back the treble must be attenuated by the same amount... This was a tequnique used in the very first generation of CDs (before 1985?), because of limitations in the original DAC designs, sort of like the RIAA curves for LP. but since then, the problems have been solved and CD's have not used that feature for the last 15 years.


De-emphasis is not somthing i'd worry about, is unlikely that you'll come across a CD that uses it, which is why some modern designs don't bother supporting it...
 
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edwinaviles

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Thanks a bunch! I'm glad I don't have to worry about it.
However, why is it even tested if it so seldomly used anymore? hmmm...


Edwin Aviles
 
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Budgie

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I have read that some CD's of older music get transfered to CD with the old RIAA vinyl emphasis still in place. Not sure if thats true or not.
 
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Dusty Chalk

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Quote:

Originally posted by edwinaviles
However, why is it even tested if it so seldomly used anymore?


Compatibility. And therefore, for completeness of testing. It's still part of the spec, and so it should still be taken care of, and correctly. I've read several "audiophile" reviews in which the reviewer is a particularly staunch advocate of getting this right, I forget whom, though. They must have one or two CD's that have this that are irreplaceable or something. Or maybe it's on Stereophile's test CD.
 
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zowie

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Quote:

Originally posted by Budgie
I have read that some CD's of older music get transfered to CD with the old RIAA vinyl emphasis still in place. Not sure if thats true or not.


I doubt it.

Most cds are transferred from tapes, which don't have RIAA curve (but could even have other curves, like NAB).

Most pre-tape recordings also are pre-RIAA curve.

For the rare case where the transfer must be made from a recording with RIAA curve, like where masters were lost, the engineer would have to be a total idiot, because it's really cheap and easy to reverse the curve before transfer.

And finally, the CD would sound atrocious, it's a pretty steep curve.
 
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