In article , John Phillips
wrote:
[snip]
I think Keywood should have a good look at Jim Lesurf's "Good
Resolutions" article at
http://www.audiomisc.co.uk/HFN/goodr...ons/page1.html (in particular
figure 5 on page 2 will show him a realistic comparison of dynamic range
of CD versus LP). Also Jim's article "In a Dither" at
http://www.audiomisc.co.uk/inadither/Page1.html would show him where his
misunderstanding about dither lies.
I also suspect that with many of the old analogue original recordings the
recorded noise level is enough to dither adequately any transfer onto CD-A
- even if the engineers don't explicitly add in dither or noise shaping whe
doing the ADC. :-)
FWIW **many** years ago I contacted him, giving much the same explanation
as on the pages you refer to above - including example spectra - and giving
details of the basic explanations. Prompted by an article he'd published
back then making similar comments to the recent one.
I hoped/assumed at the time that he'd realise he might simply be making a
mistake, and misunderstanding the situation. Point being that what I was
saying wasn't 'new' or my own idea. Just standard information theory,
supported by practice, and evidenced by appropriate methods.
Got no-where.
I'm afraid he regularly makes comments like those in the recent issue of
HFW. I read them and just sighed.
I also tend to take with a pinch of salt some of the THD values they report
for things like CD players. Partly due to the possibility they are using
undithered discs - so reporting the effect of undithered quantisation.
Partly because the values often look to me just like the noise floor you'd
get from dithered FFTs with durations in the range 16k to 64k samples.
If so, the consquence could be that the values they publish may tell you
more about their measurement system and how they 'interpret' the results
than about the CD player being tested.
Keywood starts out with "This isn't a hatchet job of the poor little
silver Frisbee" and then proceeds to try just that. In fact through his
clear technical misunderstandings the only thing that suffers a "hatchet
job" is Keywood's own reputation for competence.
As I say above, NK has form as long as yer arm on this. :-) From comments
I have heard in private, others have also given up trying to explain some
things to him. To me, this is a shame. He did do some superb work in the
past on topics like the resonances in tone arms, etc, which showed up some
very interesting things. Deserves respect for much of what he did. I also
admire HFW for when they do things like publish kits for amps or speakers
and encourage readers to get involved in building. I was pleased when HFW
started up for these sorts of reasons, and good luck to them. But... I
guess that we all get in a muddle about some things. Only human.
So I doubt he'd read the webpages you reference above [1] or, likely - if
he did - then he simply wouldn't accept what they say.
Slainte,
Jim
[1] Perhaps worth admitting here that the webpages were themselves prompted
by seeing NK make these sorts of assertions in another HFW item a few years
ago. But when producing the webpages I concentrated on the topic and
glossed over where I'd read what I was reacting to. :-)
--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio
http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc
http://www.audiomisc.co.uk/index.html
Dirty Digital [sic.]
.
Linear Mode
