Greg Menke wrote:


"C.A. Decker" writes:

Actually this is a common misconception. The actual reading of the disc
is a totally analogue process. The reflected optical signal from the
pits on the CD is not a strict "one" or "zero". The signal varies within
a lower range which we call a "zero", and a higher range which we call a
"one". There is a "guard" band between these two signal levels. It is
only the digital circuitry that comes after the disc reading process that
causes "binning" of the two signals into either a "one" or a "zero". It
may not happen very often, but it is possible to introduce errors at the
analogue reading stage. How this may or may not affect the sound I'll
leave for others to debate. However, recall that many moons ago jitter
was ridiculed and totally dismissed in the press as being an implausable
cause for any affect on the sound. If I recall, it was one of these so-
called nut case audiophiles that originally discovered and measured this
effect. I do believe that low jitter circuitry is now pretty much
standard in any decent quality digital equipment. Cheers.

Any bits flipping because of analog effects is an error reading the
medium. It happens, which is why there are ecc and checksums. Their
job is to detect and/or recover from the error- the same kind of thing
is done in more expensive computer memory to help recover from cosmic
rays flipping bits here and there, among other things.

However, how the audio nuts go from arbitrary bits flipping between
states to an organized effect like "better bass" instead of a simple
increase in random noise is very curious to say the least.

A puzzler, but I can think of a few possibilities. Unlike data, the error
correction for music is CDs is not absolute - if there is an error the
circuitry will try and play around it - and the method used to approximate
that might well involve smoothing the sound out over a certain interval of
time with interpolated values, causing better bass and worse treble
response; or if not actually improving the bass and/or overall quality,
causing a relatively better bass/treble quality ratio.

In the studio I believe it is also an occasional practice to add noise at
innaudible level to ameliorate distortion caused by the notes being exact
fractions of the sampling ratio, and some non-linearities in the overall
response, causing and a slight increase in both actual and perceived
quality.

Note that these are pure speculation, and probably wrong. Any effect, if
there is an actual effect, may well be caused by other processes. They are
just to show that it might be possible.


Like CA Decker's Jitter story, his sort of thing happens in musical
reproduction technology - for instance when "they" said "44.1 kHz is enough,
you won't get better fidelity with a higher sampling rate" and justified it
as mathematically proven under Nyquist theory, they were subtly wrong - it's
fine and true for the reproduction of constant tones, but the theory falls
down when reproducing changing notes, which after all are what music is
composed of, and when some implicit assumptions about your reproduction
equipment are untrue in practice.


I'm not buying silver speaker cables though!



More, a general improvement in faithfulness to the original causing "better
bass" is much easier to imagine possible reasons for.


--
Peter Fairbrother

The new moon is rising the axe of the thunder is broken
as never was not since the flood nor yet since the world began