From: lstowell@pyrnova.mis.pyramid.com (Lon Stowell)
Newsgroups: rec.audio
Subject: Re: How can different digital cables sound different?
Date: 7 Jan 93 01:30:59 GMT
Reply-To: lstowell@pyrnova.pyramid.com.pyramid.com (Lon Stowell)
Organization: Pyramid Technology Corporation

In article <1993Jan6.151540.16595W@lumina.edb.tih.no> ketil@edb.tih.no (Ketil Albertsen,TIH) writes:
>
>Sure bit errors occur. My point was that for all practical purposes,
>the error detection/handling IS advanced enough to cope with those
>that do occur.
>
    Between the disk and the digital output, for all but the most
    egregious errors, I'd agree.  And until they invent low-inertia
    high-torque motors which could back up the track and re-read it
    [its a joke, folks] not that bad.  Of course a track buffer that
    could buffer at least an entire track or two combined with a
    simple control mod that just re-read the same track if an
    UNCORRECTABLE error is detected would be a nice feature for a
    high end player.  That way you'd avoid ever having to
    interpolate...avoiding the debate about whether or not this is
    audible.

    This wouldn't take care of scratched CD's but it would help with
    marginal reads--particularly where the disk is a bit off, or the
    studio has taken a bit of liberty with track pitch.  And in fact
    could extend the CD specs w/o changing the size.
>
>Well, I didn't know that, but I am not surprised. BUT: To improve the
>quality on real time data transfers, retransmission is not the way to
>go unless you have a lot of excess channel capacity. Otherwise, it will
>be just too late. Error correcting codes will be a much better bet.
>Sure, that causes overhead even on successfully transmitted data, but
>we are talking real time information here. That is definitely different
>from an FTP transfer!
>
    Believe it or not, there ARE lan technologies more advanced than
    the 70's.  The 1.5 or so megabit range of digital audio could
    easily be done in reliable ack/nak mode on an ethernet, token
    ring, hyperchannel, fddi, etc. etc. etc.  

    But the poster's point was that the error-correction was NOT
    present on the external digital interfaces.  To me this is
    really silly...the coding on a CD is supposed to tolerate
    signal/noise ratios of about 3 dB if I remember correctly.  You
    could run optical or coax cables thru hell if you had that kind
    of forward error correction.   

>
>Only to illustrate how retransmission would not solve the problem.
>(There is no really significant difference between reading data off
>a cable or receiving them from the disk.)
>
    In the light of the statements that the group coding is NOT
    present on the cable but is on the disk/laser interface, I'd
    expect you to have a somewhat different opinion if you've got
    any theory on information transfer technology available.

>
>Maybe you didn't hear my sarcastic voice... If the part of the signal
>chain chain following the digital cable (DAC, amp, speakers ect.) is
>not changed, the sound produced depends solely on the input. For a 
>digital signal, the input is nothing but 0s and 1s having no other
>qualities than being 0s and 1s. If the same 0s and 1s come from two
>different sources, but are the same 0s and 1s, the input to the
>DAC/amp/speakers is identical. Unless the phase of the moon has
>some effect on the electronics, the sound will be identical, too.
>At least if analyzed by neutral means. I mean, this is a fact -
>you can't argue a fact.
>
   No, analyzed by a PERFECT DAC...and "facts" have a real bad habit
   of being someone's mental invention in my experience.

   Of course you are assuming perfect DAC's....or DAC's being fed a
   signal well within their operational limits...where the levels of
   1's and 0's are well beyond the transition region and the noise
   floor is near or below a 0 signal.   I'm still waiting for one of 
   those....


>Then comes a certain group of audiophiles, saying like that scientist
>a while ago (I'll find a reference to the source if anyone cares!):
>"Yes, I know it is a fact, but at the moment I prefer not to take it
>into consideration". And they add that there still is a quality 
>difference of the sound that, although not supported by facts,
>nevertheless is audible to them. OK, I don't believe in them, but
>I don't believe in angels or ghosts, either.
 
  Strange, I don't believe in self-styled scientists who confuse
  theory with the real world.  And I've been in audio long enough to
  watch last year's "facts" from SOME self-assured scientists become
  this years disgrace.  

  Of course this is not a chop at the real scientists....most of
  them admit that some people can hear things they can't measure
  with the tools of the moment, but don't dismiss it out of hand
  with arguments based on theory..and frequently unwarranted
  assumptions.