Re: Dirty Digital [sic.]

In article <slrng5mk67.f59.news0804@xxxxxxxxxxxxxxxxxx>, John Phillips
<news0804@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On 2008-06-19, Jim Lesurf <noise@xxxxxxxxxxxxxxx> wrote:

Prompted by what you say, I had a look at the first review of the
CDP101 in Hi Fi News. (Martin Colloms, March 1983). ... [snip] ...
Reading the article I did note one comment by MC, though. He borrowed
some recordings and CDs from various CD/LP companies. Then commented
that the only ones that systematically had a full dynamic range were
the ones from DECCA. Others were reported as being trunkated to
quantisation levels much poorer than the 16-bit level.

This was also reported in Stereophile's review of the CDP-101 (or one of
the follow-ups). See
http://www.stereophile.com/cdplayers/193/index.html and subsequent
pages.

I also notice that the Stereophile pages give a reference to an article on
Dither which Martin Colloms had published in the August 1983 issue of HFN.
So it is clear that many people in the consumer audio mags knew about this
when CD was launched. :-)


So perhaps you are confusing poor resolution *CDs* with the player
being used. Or perhaps your player was faulty.

In fact on the specific issue of digital processing with or without
dither and the effect on resolution in "reverb tails", since the CDP-101
had only analogue reconstruction filters there seems to be no
possibility to blame the player - only the CD mastering.

You having mentioned that made me check, and I can confirm that the
squarewave results in the HFN review of the CDP101 show no 'pre-ringing'. I
haven't found a detailed spec for the CDP101, and can't recall any details.
But it looks like it used the simple method of 16 bit DACs followed by an
analogue filter. The Philips method of using 14 bit x 4 oversampled
employed transverse digital filters. The symptom for this was the familiar
'time symmetric' ringing before and after each square wave edge.

Above said, what I don't know is how monotonic or linear the Sony DACs
were. But the THD results I've seen don't look particularly bad - allowing
for the kit used and the noise floor of a dithered signal and a finite
duration FFT.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
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.

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