In article , Johnny B Good
wrote:
On Fri, 17 Jul 2015 23:45:46 -0700, Phil Allison wrote:

Johnny B Good wrote:

====snip====

The remaining issue with DACs was the analogue output stage clipping
that afflicted some of the earlier products due to inadequate voltage
rail provisioning derived from the "Join the dots" peak amplitude
calculations by some rather naive designers who didn't fully
understand the process of handling a bandwidth limited analogue
signal encoded into the digital domain.

** Not real sure what you are on about here, but the maximum signal
level possible from a CD player is 2Vrms or 2.83V peak. Given that
most players have dual 12 or 15 volt supplies for the op-amps, there
is no such issue.


The "Join the dots" approach to deciding the clipping headroom required
in the DAC stages of *some* models of CD players would normally have
sufficed with most music material.

Not clear what you mean here. Do you mean "join the dots" to be linear
interpolation (a la Legato Link) or oversampling by more accurate means? If
so, what? Plain linear interpolation totally avoids having intersample
*values* that clip, but does so by distorting the data-defined waveform.


The trouble only really became evident as a result of the "Loudness
Wars" techniques where the digital processing permitted 'soft limiting'
to be taken to such an extreme as to be just shy of 'clipping'.

That has certainly been a dominating factor. But it is more complex than
that.

Its quite possible to have a series of samples which fully and correctly
defines an unclipped waveform *but* which - when correctly reconstructed -
has peaks *above* 0dBFS. And then some DACs duly clip or distort as a
consequence. In theory, the data and waveform are fine. But in practice the
DAC builder didn't allow for this.

For more detail see the URLs I gave in my previous posting in this thread.

Jim

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