Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site tekig1.UUCP
Path: utzoo!linus!decvax!tektronix!tekid!tekig1!gregr
From: gregr@tekig1.UUCP
Newsgroups: net.audio
Subject: The CD challenge!!
Message-ID: <1269@tekig1.UUCP>
Date: Tue, 23-Aug-83 01:05:12 EDT
Article-I.D.: tekig1.1269
Posted: Tue Aug 23 01:05:12 1983
Date-Received: Wed, 17-Aug-83 14:58:17 EDT
Organization: Tektronix, Beaverton OR
Lines: 69

A couple of technical points - then THE CD CHALLANGE...

Recently someone quoted ABSOLUTE SOUND as stating that CD systems had a 60 uS 
risetime.  This is totally false.  The product of risetime and bandwidth is
substantially constant at about 0.35.  Therefore if the risetime
were 60 uS, the bandwidth of the system would be about 5.8Khz!  This, of course
is nonsense.  In fact all 11 test reports of CD players I have seen published
show them no less than 1 db down at 20Khz.  Therefore they have bandwidths
in excess of 20Khz, and risetimes less than 17.5 uS.  Because risetime is so
predictable with CD systems the test reports don't even bother to publish
numbers.  For those that don't understand the math or don't believe, simply 
look at the 1Khz squarewave photographs which clearly prove the point.

Ah yes, the pulse response ringing.  This has been claimed by several writers
as the source of their objection to CD.  To me this is the ultimate farce
in the old audiophile "I can hear it, so whats wrong with your hearing?" 
argument.  The ringing displayed by CD players is nearly without exception
less than or equal to the finest, most expensive, most highly praised 
MOVING COIL cartridges available.  I speak here of cartridges selling for 
up to $1000, more than my entire CD player.  Note that most moving magnet
cartridges have very little overshoot or ringing, but audiophile pubs
like ABSOLUTE SOUND nearly always praise the sound of moving coils over
moving magnets.  So is the explaination for this amazing inconsistency
that the conventional cartridges are so bad they mask the "sound" of the
ultrasonic ringing or is it that ringing at frequencies that can't
be heard simply can't be heard.  I tend to favor the latter explaination.
Enough said!

Now the challenge - Several writers have written negative comments based
on false information of the type discussed in paragraph one, or on 
conclusions about sound quality based on test information which is 
uncorrelated to sonic perception by any known testing technique, and 
perhaps even inconsistent with other known observations as in paragraph
two.  Opinions based on this type of "creative wisdom" is rather useless
and perhaps even destructive to others.  WOULD SOMEONE PLEASE write up
their NEGATIVE comments about the sound of CD's that;

       1. Owns or has extensively (at least several days) listened
          to a CD system in THEIR OWN HOME with reasonably good
          speakers, etc. (Your opinion, I don't wish to quibble).
          No audio store demos qualify under any circumstances.

       2. Please indicate the specific nature of your complaints.
          No comments about "grey velvet texture".  If the midrange
          is depressed, say so.  

       3. It isn't required but bonus points for comparing the CD version
          with the conventional disk version of the same recording.
          Comparisons must be made at the same time however, no fair
          remembering how the conventional disk sounded last week.

       4. You must list the particular CD disks that you find objectional
          above.  As it has been made abundantly clear in the audio
          pubs many early CD disks are made from poor analog recordings
          so this is important.  For similiar reasons, also well discussed
          you may find the conventional version less objectionable than
          a bad CD disk. 

       5. Do yourself a favor and listen to at least two TELARC CD's. 

       6. **** BONUS POINTS *****  if you have purchased a CD system 
          disliked it and sold it, or regret its purchase and sound quality
          with the Telarcs or equal quality disks. 

End challenge - let those that know speak!
                (And those that haven't really listened, hush)

                                       Greg