Newsgroups: rec.audio

K. Shetline writes:
>In article <3340372@hpcc01.corp.hp.com>, kirk@hpcc01.corp.hp.com (Kirk
>Lindstrom) wrote:
Point#1
>> Have you LISTENED to a SINGLE CD player where all that was changed was
>> the Versatil Link (HP) where one had more "systematic jitter" than the
>> other?  I have and it is noticable with even a $400, 1987 technology
>> player.
Point #2
>> Have you listened to CD players with coax and TOSLINK interfaces and
>> compared the two?
>
>Yes I have. And about the only room for improvement-by-cable that I can
>find in anything mentioned here MIGHT be when one or both pieces of
>equipment at either end of the cable is badly designed or defective. I
>would think (and have stated so) that noise immunity could play a role, but
>reasonable immunity is easy to achieve and shouldn't take a pile of money.
>I suppose impedance problems could matter as well, but again only in
>marginal situations.
>
You've changed what we were discussing into something I didn't say.  I
stated that I don't believe digital cables will improve sound if the
cables are shielded and well constructed.  On this we agree.  I DID say
that jitter (some types at some levels) is audible.

Also, it was 1987 when I was the blind testee in the Denon/Versatile-Link
jitter test.  I used headphones and could distinguish between the two
jittering optical receivers, but I couldn't say which one sounded better.
This was just like how it was for me a few years earlier when our R&D lab
manager and I went to a high-end store and listened to many early high-end
CD players - they sounded different, but I couldn't say which I liked more.
Back then, my hearing may have been better, but I think I have more of a
taste for what I like now.  Also, I didn't use a reference CD (I didn't
even own a CD player then) so picking what sounds better would have been
hard.

>I'm still trying to read the January Stereophile article on jitter, but no
>newsstand around here carries it, and the local library still has nothing
>later than December available. Does the article get into cables, anyway?
>
Well worth the $19 subscription price since the newsstand price is $5 or $6.
It is entertaining and I'm impressed that they use some scientific method
in their listening tests (the low priced speaker test - <$1000! - is a good
example).  The jitter article is good work, but it raises the subject of
power supply noise induced from DAC switching transients which I've found to
be more of a problem in my work at higher frequencies and I believe it is why
the correlation they get to jitter and sound isn't as good as some would think.
What is good is that people that understand these things are discussing them
in open forums.  I think jitter is SOME of the problem or might even be a
symptom of the real problem (power supply rejection).

>As for having gone out and tested coax vx. TOSLINK, no. TOSLINK is fiber
>optic cable, correct? If so, I would think that a test of one type of coax
>vx. another might be more germane here, otherwise it complicates the matter
>with the question of whether or not the optical receiver is doing its job
>correctly. Not that I consider that a very likely candidate for signal
>distortion, but a little more that cable differences. Still, if the optical
>link produces the same bit stream with the same timing as the coax, I would
>stand by 'bits-r-bits'.
>
I wouldn't expect to hear differences in coax.  I said TOSLINK vs coax for a
reason - the TOSLINK has higher data-dependent jitter levels due to its
limited bandwidth.  Interesting thing is I was at one high-end store and
they had Aragon amp and preamp, SONY bit stream converter, ?? transport,
and Snell $3K speakers in the demo room and were using the TOSLINK rather
than the coax.  I asked why and they weren't aware that there should be
a difference.  I asked if they'd tried the coax and compared and they said
"no".  Later they told me about this "remarkable silver digital coax
replacement cable".  I think the "remarkable" part of this cable was their
$250 profit.

To tell the truth, I haven't compared digital cables so I won't say "there
is no difference", just I will say that I don't think there are differences
unless some do something "wrong" and produce a more pleasing sound for
some listeners.

>Of course, if I do try it out, and don't hear any difference, will that
>matter any to you? Maybe my ears just aren't good enough. Maybe, you might
>think, my prejudices just won't allow me to hear, or admit that I hear, a
>difference.
>
It would just be another data point from someone that took the time to do
more than just listen to what someone said.

>You would be perfectly justified in doubting the value of the results that
>I might report to you. Just as I am justified in doubting your claim that
>you do hear a difference between coax and TOSLINK. The unwillingness to
>accept subjective claims that aren't rigorously tested exists on both sides
>of the fence.
>
I said I can hear the differences between different levels of jitter in a
TOSLINK.  I would extrapolate that to "one should be able to hear the
differences between coax and TOSLINK since coax has less jitter".  Of course,
this would have to be in a system where jitter was low to begin with so 
the added jitter from the TOSLINK would be significant.

>But like I said, we all have our standards about what is worth spending
>time on. Which is why I might mention a blind or double-blind A/B test, but

I'm trying to set this up with cables between CD and preamp.  If the results
say cables are different, then I may consider digital interfaces.  My guess
it may be years away as I'm not sure if it is worth buying high-end CD
until the dust settles.

>to make much of anything out of it. Hell, even if you did, you know I would
>probably suspect the methodology. (Unless, of course, you told me what I
>wanted to hear ;-) )
>
8-)

>So what does that leave us with? Theoretical arguments, I suspect. If you
>can come up with a good reason why a cable should make a difference, you'd
>go a long way toward motivating us non-believers to take the effort to seek
>out demonstrations. Maybe even make us provide us with enough excitement
>about the idea that a salesman might actually pay attention to us.
>
>Now, if you don't think it's your job motivate anyone else, you're right.
>But, the very fact that you have engaged in this discussion would seem to
>indicate that you have some desire to change minds.
>
No, to understand the principles is my motivation since this is a hobby
for me.  If anything I did or said could help improve the state-of-the-
art, then I would be really pleased.

>The only objective information related to the cable issue that I've heard
>so far has to do with jitter producing some measureable results in some
>situations, and the only link that I can see is that since outboard DACs
>are involved, digital cable are involved. I've heard nothing objective
>about the digital cables sounding different. That doesn't mean they don't
>sound different, of course, but without statistical evidence or a
>theoretical basis, all we are left with is testimonials. Now, maybe I've
>just missed something. If so, please fill me in.
>
Again, I never said I believed digital cables sound different, but I WON'T
say that they DON'T until I've done alot more listening.  I did say that
the interfaces sound different under some circumstances (that being TOSLINKS
with different jitter values or TOS-AT&T).

>> If not, I won't bother wasting my time argueing with your religion.
>
>If you want to call ranking statistical evidence and theory above the sea
>of conflicting testimony a religion, then show me the chapel and I'll be
>there on Sunday.
>
OK 8-).  But... Math, statistics, and theory are NO substitute for listening.
If someone believes music sounds better after they burn a $20 in their
fireplace, I can't tell them that it doesn't as it is an art form and there
could be a reason that I don't yet understand (maybe the smoke from the
flame gets them high?). 

>-Kerry
>----------
Kirk out