Jim Lesurf wrote:

It is an interesting question. However for myself, the main 'bar' to
giving any answer is the absence of detailed technical information on
HDCD that would let me determine what *actual* effect the process
has... I've read all sorts of claims and general descriptions over
the years that 'describe' HDCD, but none that would enable any
analysis, etc. (Indeed, the descriptions I've seen at different times
contradicted one another!)

The effect seems to be one of a compander. Another post mentioned
something about soft peak limiting, which would resolve with the
observed effects. Many HDCD discs sound squashed dynamically when played
on a non-HDCD player.

More generally, though, I find that provided I avoid problems like
clipping, that the sound when I replay a CD I have recorded from an
analogue source sounds to me just like the source I recorded. Hence
I'd be inclined to expect this of the analog from an HDCD player as
well... But this is simply an expectation, not an actual result. :-)

Well... I've now bought myself a Sony RCD-W100 CD recorder. (Needed it
for some other work archiving historical recordings to CD without
requiring the use of a PC.) And have done a few tests.

An analogue copy of an HDCD disc with SBM (Super Bit Mapping) turned on
does indeed sound just as good as playing the original via analogue (and
sounds a damn sight better than playing the disc with no HDCD decoding).
With SBM turned off you can distinguish between original and copy, but
only back to back.

According to the manual SBM uses "a form of noise shaping to encode an
effective resolution of 24 bits into the 16-bit medium". Whatever the
jargon, it works - analogue recordings made from HDCD do sound more
detailed.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

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