"Jim Lesurf" wrote in message

In article
, Arny
Krueger
wrote:
"John Phillips"
wrote in message

On 2008-06-16, Jim Lesurf wrote:


IIRC Lipschitz and Vanderkooy were publishing about
dither in JAES in about 1984 and just after. Although
dither had been know for a long time I suspect you are
right that noise floors for material transferred to CD
were probably sufficient in the early days of CD
(1982-ish) to render external dither unnecessary.

AFAIK Vanderkooy and Lip****z were knowingly publishing
old news, in an effort to overcome some pretty strange
false claims that were being circulated at the time by
people who should have known better.

That is also my recollection. I can't remember when the
first work on dither was done, but I think it was
produced a long time ago. Hence there really isn't much
excuse for someone writing magazine articles like NKs not
to understand it. I was certainly reading about such
matters long ago.

The author that V&L were "answering" was a professor Professor PB Fellgett,
and published in 1981.

I comment on a posting of it in this post:

http://groups.google.com/group/rec.a...e7d88bbec10f81

Much of its contents are quoted.


I'd be interested in seeing data on the noise performance
of studio mics and preamps, etc. If I recall correctly,
their bandwidths also may cast some doubt on the idea
that LP recordings provide wide ultrasonic bandwidths of
genuine recorded sounds. (As distinct from distortion
products, etc.)


The quietest mics have A-weighted noise equivalent to an acoustical level
that is just under 10 dB. Most serious mics have A-weighted noise equivalent
to an acoustical level that is 20 dB or less. The weighting curve is
significant because the spectral contents of microphone internal noise can
vary depending on the technology used to build the mic.

IME it is not difficult to find mic preamps and converters that are quiet
enough that they don't materially add to the noise coming out of a typical
capacitor microphone.

"John Phillips" wrote
in message

Has anyone read the article "Dirty Digital" by Noel
Keywood in July's "Hi-Fi World"? I picked up a copy for
some amusement during a journey yesterday and was stunned
by the article's technical incompetence.

This page seems like a potential sounding board for your comments:

http://www.hi-fiworld.co.uk/hfw/email1.html

BTW, your comments seem well-reasoned, and believable, although I haven't
read the article.

John Phillips wrote:

Has anyone read the article "Dirty Digital" by Noel Keywood in July's
"Hi-Fi World"? I picked up a copy for some amusement during a journey
yesterday and was stunned by the article's technical incompetence.

Keywood says of CD that "dynamic range is limited to 85 dB or so by
dither noise" (incorrect - it's actually about 93.3 dB IIRC for 2 LSB p-p
of TPDF dither). Then he complains, disingenuously, about the "dirty
distortion" of quantization on CD (he calls it "digital distortion"),
misunderstanding the fact that it just isn't present when you use dither.

Yeah, so he's a ****. He works in hi-fi. What did you expect ?

Maybe it's all part of a big plan to get us to go back to valve radiograms ?

Graham