"John Phillips" wrote
in message
On 2008-06-16, Jim Lesurf wrote:
In article ,
John Phillips wrote:

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. :-)

I have wondered about that and the CD-A timeline.

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.

One of my musings was that for a short period after ADCs
got better it may have been that CDs lacking dither but
displaying the effects of quantization noise might have
made it onto the market. I have no idea if this did
actually happen, though.

The earliest CD players had converters good enough to demonstrate dynamic
range on the order of 93 dB, which is pretty close to the theoretical max:

http://www.pcavtech.com/play-rec/Son...ndex.htm#DR_DA

About 15 or more years later, a highly-regarded CD player improved on the
legacy players performance by only about 1 dB

http://www.pcavtech.com/play-rec/cd67se/index.htm#DR_LB

The noise floor of a well-made recording is on the order of 75-80 dB. Below
that is the noise floor, usually from analog (thermal) sources. This is many
times more than is required to properly dither a proper 16 bit conversion.