TCI Cobra interconnects against Chord Chameleon
 

Don Pearce wrote:

Jim Lesurf wrote:
In article , John Phillips
wrote:
On 2008-07-15, Don Pearce wrote:
John Phillips wrote:
Do you have particular example where you think the lumped and
transmission line models will differ in a cable-speaker application
to a degree that is practically relevant?
Not handy. But it is clear that the lumped version of the model is a
lowpass filter, which a cable simply isn't.

The lumped version presumes a 'short' cable in wavelength terms. For audio
frequencies and runs of a few metres this is generally quite a decent
assumption.


Ah but how short - that is the question. Here is another graph, this
time of the loss of 10 feet of Monster cable into an 8 ohm resistive
load. There are three traces, one in which the lumped elements are all
in one piece, another where they have been split into 20 equal sections
and yet another with 30 sections. Now, which one is "right"? The
legends tell you which is which.

http://81.174.169.10/odds/sections.gif

Is that f scale in Hz or rads / sec ?

Graham

TCI Cobra interconnects against Chord Chameleon
 

On 11 Jul, 10:18, max graff wrote:
Dear all,

I have been using the adorable Chord Company interconnects and speaker
cables for a while. Has anyone reviewed TCI Cobra interconnects
against the Chameleons? If so I would like to know your experiences.

Cheers Max

HI Max,
As soon as I saw this I thought "oh no,cringe moment!" You are in the
wrong place to ask this type of question!Most of the main contributors
are in denial that such things as cable quality and design can, God
forbid, change or improve the sound of a system.
Don't waste your time here.
Good luck,
Borosteve.

TCI Cobra interconnects against Chord Chameleon
 

"borosteve" wrote in message


On 11 Jul, 10:18, max graff wrote:

I have been using the adorable Chord Company
interconnects and speaker cables for a while. Has anyone
reviewed TCI Cobra interconnects against the Chameleons?
If so I would like to know your experiences.


As soon as I saw this I thought "oh no,cringe moment!"

You are in the wrong place to ask this type of
question!

Actually, his question was timely and appropriate. Max has obviously been
taken in by magic wire mysticism.

Most of the main contributors are in denial that
such things as cable quality and design can, God forbid,
change or improve the sound of a system.

Shows how much that we say goes over your head, Steve.

Poor cable quality and design can hurt the sound of a system. I think about
all those of people who spent the big bucks on vastly overpriced Monster
Cable 18 gauge speaker cables and the inflated claims that were made for
them at the point of purchase. They could have bought commodity 12 gauge at
a nearby home improvement store or a good electronics store like Maplin.
They would have got better sound, and left a little money in the bank for
new recordings. But, they were sucked in by the Monster Cable branding.

TCI Cobra interconnects against Chord Chameleon
 

Don Pearce wrote:

Eeyore wrote:
John Phillips wrote:
Jim Lesurf wrote:
Don Pearce wrote:

Speakers are particularly interesting in that there are many cables
available, some of which (from Goertz) have inductance and capacitane
which together come down to around 8 ohms as a distributed impedance.
These cables, despite having enormous capacitance, are essentially
ruler-flat in frequency.
The last sentence is meaningless as it has no reference to the conditions
of use. A 'cable' doesn't have a "ruler flat" response. What you get
depends on the system. And as soon as the load doesn't match the cable
perfectly, the source matters as well. Problem here is that domestic LS
uses a voltage assertion approach with loads that have values that vary all
over the shop.
However my simulations suggest Don is quite right in the sense that a LS
cable with a lower nominal impedance interacts less with most loudspeaker
loads and in general results in a flatter frequency response for the
voltage transferred from the amplifier to the LS.

This does assume the amplifier is stable driving the load.

And just how the LS and the room then deal with that input voltage is,
of course, another matter which may make that flatter frequency response
less relevant.

The concept of cable 'impedance' at audio frequencies is INSANE for a few metres
length.

It's the bulk R, L and C that effectively matter.


Really - did you not see this? Have a look and tell me you think the
bulk parameters are what matter again. The bulk parameters are
represented by the curve with 1 as the first parameter. The one with 30
comes close to a true cable performance.

http://81.174.169.10/odds/sections.gif


Yes I did see it after I posted the above comment. It's very interesting but the
effects seem to be in the infrasonic region AFAICS.

Since the issue arises, I've always been very intriguged about the 'lumped sum' model
vs more elaborate versions.

Do you have any cites that can explain it better ?

Graham

TCI Cobra interconnects against Chord Chameleon
 

borosteve wrote:

max graff wrote:
Dear all,

I have been using the adorable Chord Company interconnects and speaker
cables for a while. Has anyone reviewed TCI Cobra interconnects
against the Chameleons? If so I would like to know your experiences.

Cheers Max

HI Max,
As soon as I saw this I thought "oh no,cringe moment!" You are in the
wrong place to ask this type of question!Most of the main contributors
are in denial that such things as cable quality and design can, God
forbid, change or improve the sound of a system.

Improve ?

They can unquestionably affect the frequency response, well for speaker
cables at least ! That's plain physics.

It's also plain physics that component interconnects CANNOT affect the sound
ONE BIT unless the equipment concerned is inappropriately engineered or
defectively designed. The use of valves (tubes) would be a case in point
with their typical high output impedance and hence sensitivity to cable
capacitance.

It's really very simple. Audio pros have known all this for many decades.

Graham

TCI Cobra interconnects against Chord Chameleon
 

Eeyore wrote:

Don Pearce wrote:

Eeyore wrote:
John Phillips wrote:
Jim Lesurf wrote:
Don Pearce wrote:

Speakers are particularly interesting in that there are many cables
available, some of which (from Goertz) have inductance and capacitane
which together come down to around 8 ohms as a distributed impedance.
These cables, despite having enormous capacitance, are essentially
ruler-flat in frequency.
The last sentence is meaningless as it has no reference to the conditions
of use. A 'cable' doesn't have a "ruler flat" response. What you get
depends on the system. And as soon as the load doesn't match the cable
perfectly, the source matters as well. Problem here is that domestic LS
uses a voltage assertion approach with loads that have values that vary all
over the shop.
However my simulations suggest Don is quite right in the sense that a LS
cable with a lower nominal impedance interacts less with most loudspeaker
loads and in general results in a flatter frequency response for the
voltage transferred from the amplifier to the LS.

This does assume the amplifier is stable driving the load.

And just how the LS and the room then deal with that input voltage is,
of course, another matter which may make that flatter frequency response
less relevant.
The concept of cable 'impedance' at audio frequencies is INSANE for a few metres
length.

It's the bulk R, L and C that effectively matter.

Really - did you not see this? Have a look and tell me you think the
bulk parameters are what matter again. The bulk parameters are
represented by the curve with 1 as the first parameter. The one with 30
comes close to a true cable performance.

http://81.174.169.10/odds/sections.gif


Yes I did see it after I posted the above comment. It's very interesting but the
effects seem to be in the infrasonic region AFAICS.

Since the issue arises, I've always been very intriguged about the 'lumped sum' model
vs more elaborate versions.

Do you have any cites that can explain it better ?

Graham


I only extended that high so the effect was clear. In the audible range
it is still happening, and the fully lumped simulation still heads off
in entirely the wrong direction.

An explanation, it is simple. we are trying to model something
inappropriately. In a limited range of cases it can - pretty much by
chance - give results fairy close to the correct ones. But a cable isn't
a lowpass filter, and never will be. The distributed model is the only
one which will always provide the right answer. As it is so trivial to
use, I use it rather than trying to work out how appropriate a lumped
equivalent is going to be, how many sections I need to chop it up into
etc etc etc.

As to models being complicated, I think two parameters, Zchar and length
are quite a lot easier to use than perhaps thirty inductors and sixty
one capacitors.

d

TCI Cobra interconnects against Chord Chameleon
 

"Eeyore" wrote in
message

It's also plain physics that component interconnects
CANNOT affect the sound ONE BIT unless the equipment
concerned is inappropriately engineered or defectively
designed. The use of valves (tubes) would be a case in
point with their typical high output impedance and hence
sensitivity to cable capacitance.

It's really very simple. Audio pros have known all this
for many decades.

One of the big ironies of life is that pros use pro equipment built and
wired to pro standards to make the vast majority of all recordings. If
so-called bad wiring hurts sound quality, then the damage is done in spades
on the recording/distribution side.

Some consumers have been sold a bill of goods about how an expensive 8 foot
power cord or a 1 meter interconnect can somehow undo the effects of miles
of power line and 100s of feet and many runs of signal cabling.

No harm was done by the wire, so nothing needs to be done to fix it.

TCI Cobra interconnects against Chord Chameleon
 

In article ,
Arny Krueger wrote:
One of the big ironies of life is that pros use pro equipment built and
wired to pro standards to make the vast majority of all recordings. If
so-called bad wiring hurts sound quality, then the damage is done in
spades on the recording/distribution side.

Some consumers have been sold a bill of goods about how an expensive 8
foot power cord or a 1 meter interconnect can somehow undo the effects
of miles of power line and 100s of feet and many runs of signal cabling.

No harm was done by the wire, so nothing needs to be done to fix it.

Don't be silly. True audiophiles don't listen to commercial recordings.
They have their material delivered direct from the planet Zog to make sure
it is truly oxygen free.

--
*Why is it that most nudists are people you don't want to see naked?*

Dave Plowman London SW
To e-mail, change noise into sound.

TCI Cobra interconnects against Chord Chameleon
 

Jim Lesurf wrote:
In article , Don
Pearce
wrote:
Jim Lesurf wrote:
[big snip]

OK - this is all on hold for the moment. Interested though why you are
including EM field velocity - is there some point to be made?

You'll have to read the series of articles to see all the reasons I took an
interest in velocity as well as impedance. :-) However...

Two points.

1) I noticed that there seems a distinct pattern where the wave velocity
varies from cable to cable in a way correlated with the cable impedance.
First noticed it when analysing other people's measured results, but my own
measurements threw up the same pattern. Found this interesting.

2) I think some people make a fuss about the wave velocity in terms of
arguing about 'time smearing'. So I looked at that in transmission line
terms. But I then went on to examine the non-matched more realistic cases
to see if the idea stands up. Results in articles, but you can probably
guess my conclusion. :-)

From basic transmission line theory there is no obvious 1st order reason
why the velocity should vary correlated with the impedance. So I covered
this for the above reasons.

Slainte,

Jim


OK - wave velocity is simply a factor of geometry - specifically how
much of the electric field is within the dielectric and how much in air.
Generally the closer the two conductors are to each other, the more the
field is concentrated within the insulator - and of course the lower the
impedance. But the one is not because of the other. It is quite easy to
make a ten ohm cable with no insulator - velocity equal to free space light.

d

d

TCI Cobra interconnects against Chord Chameleon
 

In article , Don
Pearce
wrote:


An explanation, it is simple. we are trying to model something
inappropriately. In a limited range of cases it can - pretty much by
chance - give results fairy close to the correct ones. But a cable isn't
a lowpass filter, and never will be. The distributed model is the only
one which will always provide the right answer.

Motes versus beams, I fear. :-)

Distributed models also only provide the "right answer" if you ensure all
the cable parameters have the correct frequency dependence *and* you model
an appropriate situation.


As it is so trivial to use, I use it rather than trying to work out how
appropriate a lumped equivalent is going to be, how many sections I need
to chop it up into etc etc etc.

in my experience, when doing this you also need to worry about the
computational accuracy and how your model is being computationally
implimented. Otherwise a 'more accurate' model in principle ends up giving
results less like reality. :-)

The above is a particular problem when using a package like Spice, MathCad,
etc, where you may not know how the package is using the values you have
specified to work out an answer.

As to models being complicated, I think two parameters, Zchar and length

Erm... Three, as you'd also need the propagation constant.[1] And of course
both Zc and will have two values each since they are complex (unless you
are deciding to ignore some parameters...)

are quite a lot easier to use than perhaps thirty inductors and sixty
one capacitors.

...but not much different in terms of "being complicated" to using three RLC
values for the cable. :-)

BTW I'm also puzzled by why you need 2n+1 caps for n inductors for your
model. Why not n+1 and just use half values at the ends? Or are you just
getting the number up to make the point you want to make? :-)

Slainte,

Jim

[1] Unless, of course, you are insisting upon the rather unrealistic
approach of assuming people always compare/choose LS cables on the basis of
moving the amp towards and away from the speakers to be able to compare
cables of appropriately different lengths in order to force them all to
have the same nominal propagation delay when matched (which in general,
they aren't, of course.) That said, I'd agree that moving the amp to just
beside the speaker and using cables of mininal length makes sense...

If you can do it. :-)

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
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