From: shetline@bbn.com (Kerry Shetline)
Newsgroups: rec.audio
Subject: Re: How can different digital cables sound different?
Date: 7 Jan 93 07:05:33 GMT
Followup-To: rec.audio
Organization: BBN
NNTP-Posting-Host: bbn.com

In article <184819@pyramid.pyramid.com>, lstowell@pyrnova.mis.pyramid.com
(Lon Stowell) wrote:
> 
> In article <shetline-060193111942@128.89.19.85> shetline@bbn.com (Kerry Shetline) writes:
>     Most commercial circuits I know of a 0 is at least 0.7 volts or

Mea culpa! Okay, so 0.7 would have been a better example voltage for a 0.
But it was only an example, and not at all critical to the point I was
making.

>    And modems REALLY don't need Trellis coding...group delay
>    distortion is just a myth after all.  And manchester coding is

When I talked about "magic" I didn't mean anything about noise problems
where 0s and 1s get flipped and result in outright error. I think I've made
it plain that I understand that is exactly what happens when noise gets out
of line. And I certainly wouldn't dismiss the need for error correction
codes.

What I meant was this: Some people seem to think that there is something
beyond the 0s and 1s and their appropriate timing. (And PLEASE. I am
talking about data transmission here. Not about the quality of analog
filters or the linearity of DACs, or other things that I agree can make a
difference.) There is an imagined magic realm where the green magic marker
effect (et al) can get through, even if, with or without this or some other
favorite tweak, the bits and their timing are the same, correctly
transmitted and received.

So can we at least agree on this: That for any given DAC, that if it
receives a bit stream that differs from another bitstream only by noise
below the level that could flip a bit or screw up a clock, that the DAC
would produce the same output? That those Schmitt triggers will do their
jobs and make a 0.7 volt 0 indistinguishable from a 0.8 volt 0, and a 4.5
volt 1 indistinguishable from a 4.9 volt 1, as far as all later stages in a
digital circuit are concerned?

>    Gimme a break.  And PLEASE don't design any LAN interfaces....

Okay, okay. We get the picture. You're a LAN God. I bow before your LAN
expertise.

Are you suggesting that the interface between a transport and a DAC is as
hostile as a LAN? Or a modem? Or just recommending conservative
engineering? Perhaps I just missed it, but could I have your opinion on
whether one digital cable can sound better than another, provided that
connections are solid and noise is below the bit-flipping level? And would
this difference be subtle or blatant?

>    problems, then all those Schmitt triggers and stuff must be due
>    to hallucinations, right?
>
>    And modems REALLY don't need Trellis coding...group delay
>    distortion is just a myth after all.  And manchester coding is
>    really unnecessary, as after all everybody knows that a 1 is a 1
>    and a 0 is a 0.  And PLL clock recovery circuits are a total waste
>    of time as they are never necessary.  And jitter buffers are a
>    marketing gimmick designed to raise the price of LAN cards.

I find it very annoying for someone to be so snide when they are reacting
to their own misinterpretation.

-Kerry
Newsgroups: rec.audio