From: ankleand@mtl.mit.edu (Andrew Karanicolas)
Subject: Re: A Golden-Ear perspective on CD players.
Keywords: flame bait, CD accuracy
Organization: MIT Microsystems Technology Laboratories
Date: Thu, 9 Apr 1992 02:35:24 GMT

In article <1992Apr6.151402.16683@cbfsb.cb.att.com> dud@cbnewsf.cb.att.com (William F. Dudley Jr.) writes:
. . stuff deleted
>He can't get net news, so don't bother trying to flame him by posting.
. .I'll flame it anyway
>amazing thing, to me at least, is that new technology was able to
>replace completely the older, cheaper, more reliable, established,
>and superior technology.

What?

>    The Physics of the CD start off pretty simply.  Each second is

>sounding cassette decks with no response over 16000 Hz, so this isn't
>necessarily bad news.  The problem is that while analog errors are

What?

>harmonic and musically unobtrusive, errors made in extracting high
>frequency information from not-too-much-higher sampling rates are
>dissonant like somebody hitting a frying pan everytime the music gets

That's exactly what I thought it should sound like.


>    And depending on how awful you can stand your music, you can have
>as close to 90 dB dynamic range as you like.  At the 90 dB level
>claimed by many CD advocates, the lowest level is just one bit and
>there is only a rasping sound to tell you that something is playing.

Do you mean the effect of an LSB change when the signal is -90dB
compared to full scale?  Or, do you mean the signal is full scale and
the effect of a single LSB change is considered?  What do you mean?

>If you insist on telephone quality, then you have 60 dB left for your
>so-called dynamic range.  And a phonograph record 60 dB below its
>maximum usable signal sounds a lot better than a telephone.

Well, telephone is kind of a bad example considering it doesn't use
linear quantization.  But lets not worry about that, after all, bits
are bits.

>
>    This is not an issue of noise.  After all, a CD has no noise
>while analog media are inherently noisy.  This is merely how quiet
>can a signal get and still sound musical.  Analog signals can be far
>below noise levels and still be acceptable while the digital lower
>limit is a signal floor rather than a noise level.

You are truly confused.  Analog signals that are far below noise power
are highly unnacceptable.

>    At this point the lightbulb began to glow.  What I heard from the
>Wadia is better than 44000 samples at 16 bits ought to sound based on
>my intuition.  And the more expensive Micromega would appeal to every

well, just how many samples and how many bits do you think are enough?

>    The other realization I came to is that every part of the chain
>is sonically significant just as in a phonograph.  The transports are
>different, the mechanical support of the CD in the transport matters,
>and the digital cable from transport to converter has sonic impact.
>The only piece of equipment that has any business sounding different
>is the converter since, as any New York cabdriver will tell you,
>"bits is bits."  Folks have measured the transports and found the
>error rates close enough to zero not to matter.  If two identical bit
>streams sound different, and they really do, then the two things
>being compared are not truly digital but rather are quantized analog
>signals.  And all the other "digital" hype is up for grabs as well!

Sorry, but you are totally confused.  If I have two UNIX files and
they are different pieces of text does this mean that the files
themselves are not truly digital?

>was staggering.  This further supports my claim that the CD is really
>quantized analog signal rather than any form of digital.  Further,

Oh my gosh!  You got something right!  Yes!  The CD stores digital
information which was obtained by quantizing an analog signal.  That
is what ANALOG-TO-DIGITAL conversion is called.  Notice the TO-DIGITAL
part.  The reverse process is called DIGITAL-TO-ANALOG conversion.
Notice the TO-ANALOG.

>    In summary, I've been able to salvage decent sound out of the CD
>for only a couple of thousand dollars.  In the process I've learned

Funny, a couple of hundred seems to do wonders.  But, we are not as
particular as you.

Andrew Karanicolas
MIT Microsystems Technology Laboratory
Newsgroups: rec.audio