From: kellyj@leland.Stanford.EDU (Kelly Johnson)
Newsgroups: alt.music.rush
Subject: Re: Digital vs. Analog
Date: 27 Jan 93 03:51:28 GMT
Organization: DSG, Stanford University, CA 94305, USA

In article <C1Hrrv.35F@unccsun.uncc.edu> rgrozier@uncc.edu writes:
>
>Digital vs. Analog...
>I've been wondering about this alot lately also.  I think a digital 
>system is the way to go for all reasons listed previously, plus 
>maybe a little more. 
>
>The brain cannot distinguish infinitely many different sounds.  
>There is a limit to our ability to differentiate subtle changes in 
>the components of sound - frequency and amplitude.  Therefore, 
>a reasonable setup for the digital recording of sound (I think it's
>~44kHz sampling rate and 16bits of storage) should be adequate 
>to record what humans _think _they hear.  Sure that leaves "gaps" 
>in the music played back.  But can we notice it?  I don't think so.
>
>There is, however, a slight drawback to CDs that I've noticed.  It 
>seems to me that CDs don't have the sound dynamic quality that
>albums on vinyl have.  By dynamics, I mean the difference when 
>the music on the recording (not when the listener changes the 
>volume) goes from very quiet to very loud.  The difference seems 
>to be greater on an album, i.e. the albums have more "punch".  
>I haven't figured out why - maybe just my imagination.
>
>As for Rush adding "filler" to their newer music, I think they're just
>taking advantage of the lack of time restraints on a CD.  Perhaps 
>on future releases, they will find even better ways to utilize the
>CD format.
>
>Richard Rozier
>UNC Charlotte

A few things to consider...
   1) Any cutoff (sampling rate) is going to cause distortion unless
      all of the instruments being sampled are "naturally" band
      limited to frequencies below a certain amount.  If you
      want to "exactly" reproduce a square wave for example, you
      could not do so with ANY sampling rate.  The question is
      how close is close enough.  Well, the human ear is said
      to be band limited to an upper limit of about 20Khz.  A
      44Khz sampling rate will allow you to have frequencies present
      up to about 22Khz (above the range of audible hearing).
      In theory, any sampling is causing distortion.  The question
      is "Does it matter" and "is it less than that induced in
      an analog recording"?  An analog recording is bandlimited
      as well (especially on the low end for vinyl) because of
      limited space on the vinyle for wide grooves and on the
      high end due to saturation on tape equipment.  Finally, as
      I said before...your ears do some band limiting and filtering
      as well so they "distort" the true sound to a certain
      extent.  There are "distorting factors" through the whole
      system, but the attempt is to do as good a job as possible.

   2) CD's have much more dynamic range "CAPABLE".  They may not 
      always use it, but it's there.  I'm not an expert on 
      CD recording standards, but your dynamic range is limited
      by the number of bits per sample due to quantization noise.
      More bits means less noise and more signal-to-noise ratio.
      16 bits gives you quite a bit of range, but obviously more
      would be nice.  Does anyone know at what point you reach
      the point where your signal-to-noise ratio is so low that
      other things in the system (background noise, analog filters,
      your EARS, etc.) begin to take over and make more bits
      unimportant?  I don't happen to know.

   3) Notice the latest buzz-word in CD technology...
      the "1-bit DAC" listed on the front of almost any new portable CD
      player.  This does not mean 1 bit per sample.  It means they
      use a new Digital to Analog converter algorithm.  It still
      achieves the same (12, 16, 20 bit) quantization, but it
      does so with a single bit comparator oversampled to the tune
      of may 1MHZ or more instead of 44KHz.  Kinda neat way to
      do it actually.  The REALLY cool thing is that what they
      are REALLY doing is building a CHEAPER D-to-A circuit,
      giving US the same high quality sound, and increasing their
      margins at the same time (unless they lower the price).  An
      oversampled 1-bit DAC is much cheaper than a 16 or 20 bit DAC.


Finally, I think you are imagining that you have more dynamic
range on vinyl.  Either that or you have some bad CD's.  I have
some CD's that have very poor dynamic range between mellow
parts and high-energy parts, but this isn't the norm.  The
range is one of the nice things about CD's.  It's also the reason
why there are so many warnings on portable CD players about
volume through headphones.  The dynamic range is significantly
higher than that of cassettes or vinyl.  The noise is much lower
as well,  which contributes to this dynamic range.  Give CD's
another shot.  Try getting some that were digitally recorded
or mastered.  A couple that I know of that are quite good
(for dynamic range) are Billy Cobham's "Fair Warning" (or something
like that).  I think Dire Strait's "Brother in Arms" is pretty
good too.  There's always the 1812 overture. 
Newsgroups: alt.music.rush