Lou Anschuetz wrote:
chung wrote in
news:d6N7b.413447$uu5.75550@sccrnsc04:
Lou Anschuetz wrote:
(Stewart Pinkerton) wrote in news:bjnmtj014u5
@enews3.newsguy.com:
At audio frequencies, you will *never* measure artifacts in cables
above -140dB referred to a 10 vrms signal, and usually much lower
than that, right at the -160dB or so limit of the measuring gear.
While there may be no _audio_ research going on in this area, there
is other continuing research on insulation properties at low
frequencies.
At very low voltages, with frequencies just above the
audio range, this is certainly active work.
Can you provide a little more detail on what research you are talking
about?
Actually no. It would be unwise for me to comment on unpublished
research.
Well, you were making it sound like it is research that is well known to
be ongoing. Is it active work only at your place of employment?
There are also known effects at 60hz, which is in the audio
range.
Again, what effects are you talking about?
So, there are effects at very low voltages at reasonably low
frequencies and there are effects at higher voltages at audio
frequencies - I find it hard to simply assume that in the middle
of that curve there are absolutely no effects. I will certainly
grant that it might as easily not be the explanation for anything,
but there is reason to suspect...
What are those reasons?
As I started out, this may not be directly applicable, but there are
clear issues here that are not QED.
What are those clear issues that have to do with delivering audio
signals to speakers, or from one output to another input?
Quality, type of insulation (in regards to EFI, EMI, RFI, etc.
etc.). Quality/type of connectors in regards to things as varying
as insertion loss (fiber), crimped vs. soldered (turns out that
crimping fiber cables may be better than glueing - interesing in
that a lot of audio equipment manufacturers are alleging the same
thing to be true with copper. Obviously different reasons/effects,
but new information. This is not exhaustive, but just some
an example.
But shielding issues are well understood and practically non-issues with
speaker cables. Of course, the fact we understand these things does not
prevent from someone incompetent to screw up the implementation, but you
can't say that our understanding is incomplete because someone screws up
the implementation.
What new informatin has come out about audio cables in the last 30
years? (We're not talking about fiber-optical cables here.)
While nature is wonderful, it is also pretty consistent. To believe
that the range 20-20,000 is somehow protected or asymptoted out of
all effects is, IMHO, pretty bold.
No, it's just a range that is easily handled by cables, and it has been
handled successfully for decades. We're not talking about delivering
kilowatts of power or nano-amps of current here. Let's get practical.
Yes, many individual effects can
be said to be negligable - but with the complexity of a musical
signal, there is the *potential* for multiple small effects to
interact. I'm not trying to rule out Occam's Razor here, just pointing
out that this stuff is not easy to model perfectly.
If such effects are not negligible, how come we still have not found
them, after using cables for decades? Do we need to model a cable
perfectly to one part in a trillion? Let's get practical. We are talking
about deliveriing audio, which is band-limited, at power levels that can
be comfortably handled.
I think it is unwise to
characterize all of materials science as old/completed science.
Now you are making a straw man.
Not all all... See below
For speaker cables and interconnect cables, there is no new discovery,
or research to be done, in the last several decades, as far as I know.
As I noted above, there is no work specifically related to Audio that
I know of. That doesn't establish that there is no link between
what is happening research-wise and what happens with audio signals.
Let's go back to Materials Science 101 for just a moment.With the
exception of a perfect vacuum (which we don't have anywhere) there is
no perfect insulator. All materials react in some way to
electrical/magnetic fields. Fortunately, electricity mostly acts like
water and doesn't "leak out" like alpha particles 
But, those
insulators around wires do react. I'll certainly grant any day of
the week that at low voltages and mostly small frequencies, those
reactions may be *very* weak. However, with the complexity of a
musical signal, the rules tested for single frequency, single voltage
reactions *may* not apply in a linear way.
We have been looking for non-linear effects in cables at the current
levels required for audio reproduction for decades. We have not found
any limitation even at signal to noise ratios of 140 dB.
If you know that linearity in a cable is good down to the 140 dB level,
then you should feel confident that music, as a complex signal but made
up of sinusoids, should have no problem being transmitted faithfully.
You don't sweat the details about how complex music is, when it comes to
cables. Look at it another way, the non-linearities from the rest of the
chain are easiliy a million times worse. Which should you focus on?
Not a lot of folks spend
a lot of time looking at this (other than high-end cable makers) since
there is, frankly, little value or profit. But, you'll also note that
there is no uniform, best-of-breed, do-all, be-all cable construction
for audio either.
No one said that. Mechanical reliability is important.
This is the likely outcome of modeling when there
are lots of parameters with potential multiple interactions.
You are needlessly complicating a straightforward situation. Do you
worry about how the indiviudals electrons behave in an amplifier?
In fiber
optics there is a "best of breed" for insulation, construction - though
the crimp-on fiber connector is *new* (relatively) and the result of
continuing research.
Fiber optics carry optical signals with Gigahertz's of modulation
bandwidth. Please have some appreciation for the scale of things.
Most every cable user I know of (and I know a lot in both research
and manufacturing) check every spool of wire that comes in. A lot of
it doesn't pass master.
You mean "muster"? That's what they, the marketing guys, want you to
believe.
Some does, but still doesn't work.
How does a piece of copper cable not work?
I know of
a certain large bulb manufacturer who tests all filament wire, but
some that passes still doesn't work right.
Again, you have to appreciate the difference in scales. Filaments are
totally different, because they have to give light efficiently and last
a certain minimum of time. It is a very different application, and it is
not pure copper.
It may be a slight
difference microscopically, but it kills the unit. This is certainly
an example of a well-known, well-engineered process that somehow
still goes wrong.
There is no process that cannot be screwed up, although making a speaker
cable comes pretty close. The fact that the process goes wrong does not
necessarily mean that there is something esoteric going on.
Engineering still has some room to grow to make
those manufacturing processes work correctly every time. Hmmm, is it
possible that some audio cable manufacturers don't check every spool
and thus their general quality is lower - thus producing a "worse"
sound? Good research question there.
I can't think of a less useful research question.
All of us involved with music know that there are effects with every
cable.
All? Are we talking about normal cables, like the ones they sell at
Radio Shack? Are we talking about effects like gauge size vs. current?
For those of us doing live sound we try to use the best
insulated (typically coax) cables we can to reduce stray effects.
Any, every mixing console I've ever seen has a built in 80hz roll
off control to eliminate breathing, as well as the occasional 60hz
hum that is so prevalent.
Are there effects other than shielding that you have seen? You think
"breathing" is affected by the coax cable?
We all know that that effect penetrates
coax cables, which in theory should be mostly immune (and yes, I do
know that this is most often the result of the electronics rather than
the cabling).
No, we don't know that the "breathing" effect "penetrates" cables.
Remember that I too hear no differences between competently designed
interconnects and toslink cables. I do, however, contend that some
speaker cables, for whatever reasons, do sound different.
Ehh, perception biases?
I also know
that testing such cables via human hearing is frought with difficulty.
Some early, unpublished (and potentially invalid) research I did many
decades ago as an undergraduate suggested that people couldn't
even identify their own voice vs. someone else's (even of a different
gender!) in some studies. That has the potential to be quite
damming in certain areas of research, so might be quite hard to get
funding for But it has always made me aware that testing by
listening alone is not to be trusted - thus gives me pause when
suggesting any kind of "audio" test of cables will be conclusive.
But, I also know that cables do sometimes act in funny ways. Until
someone can adequately model every potential agent acting in random
ways concurrently in a cable, there is room for some healthy
scepticism about whether or not they make a difference.
Please list those funny ways, and see if we can sort them out. I think
that makes for a much more productive discussion.