[LAU] Rolling off high frequencies when mastering?

micromoog micromoog at gmail.com
Wed Apr 21 18:47:32 UTC 2010

On Wed, Apr 21, 2010 at 1:51 AM, Arnold Krille <arnold at arnoldarts.de> wrote:

> The highest frequency possible to reproduce -with correct amplitude- is
> half
> the sampling-rate _only_ if the phase is aligned to the sampling-clock so
> that
> minima/maxima of the sinus are correctly sampled. If its out of phase, the
> amplitude is not reproduced correctly.

Wouldn't that only apply to a signal *at* Nyquist, which by definition is
not covered by the sampling theorem?  How would it even be possible for a
signal at, say, 22.04 kHz be phase-aligned to the sampling clock?

> It is easy to understand that this correlation between phase and correct
> amplitude also affects frequencies below half the sampling-rate. Might be
> as
> low as quarter of the sampling-rate, which in case of the CD is 11kHz.
> Below
> that you will have more then four samples to reproduce the sinus wave.
> That is in fact another reason to do the recording, mixing and mastering in
> more then 44kHz...

This is a pretty bold claim, and contradicts Nyquist and other literature.
Do you have a citation for the claim that frequencies "as low as a quarter
of the sampling-rate" are damaged by sampling?
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