Keith G wrote:

"Rob" wrote in message
om...
Jim Lesurf wrote:
I got my latest copy of 'Stereophile' yesterday and started to read
it. I
came across comments by Paul Messenger about some work that Russ
Andrews and Ben Duncan have recently put onto the web. This seems to be
taken by Paul Messenger as showing that Russ's claims re some of his
products are "now supported by proper scientific analysis". But
having looked at

http://www.russandrews.com/downloads...estPremRes.pdf

[above file size 700K]

I can't say I agree with that belief simply on the basis of what the
above
contains. But that may in part be because I've examined a past set of
measurements by Ben Duncan and come to rather different conclusions
to the
ones he and a co-author asserted about them at the time.[1] I would
therefore like to know all the measurement systems/proceedure details
that
are sadly omitted from the above. I thought others here might be
interested to read the above pdf and
consider it for themself.


It's difficult for me to tell. Everything Ben Duncan claims on his web
site is not substantiated or qualified (international reputation,
unique, expanding, holistic, world class and so on) and his
qualifications appear worthless in the sense I think I could get them
by filling out a form and paying. Following the link to his
publications leads me to a shop. Searching the shop for his name
brings up electronic things to buy and a series of collections of
articles.

He may well be a jolly good bloke but I simply wouldn't trust anything
he has to say from the impression I get from his web site. Maybe poor
self-publicity is a characteristic of scientific types, present
company excepted :-)

So, from a lay point of view, it means very little to me. I wouldn't
buy anything off the back of it, put it that way. Or at least I'd hope
I wouldn't . . .


:-)

Also from the 'lay POV', I would like to say that the trouble with these
'snake oil bashing' sessions is that they are never cut and dried
conclusive and it always falls back to individual, subjective decisions
about what 'works' and what doesn't, once you get past the obvious 'the
light is on, the light is off' stage when making comparisons. It was
probably over 50 years ago now, I said here that the only two things
that matter when it comes to 'hifi tweaks' are a) you are positive you
can hear an improvement or, at least, think you are and b) you can
afford to buy them without starving the kids!

OK, that's power leads all nicely sorted and we all know where we stand
on them, don't we? As it's easier to make my point with them, let's do
speaker cables now....

Take a squint at this:

http://www.moirac.adsl24.co.uk/Strand.jpg


Nice photo!

Right now I am listening to perfectly fine ('normal') sound from the
radio on a *single strand* of copper wire - all the way up to heap
plenty loud and down again! (Pucci's milkman isn't due here for ages so
I asked Swim to comment on the sound without telling her what I was up
to and, like me, she found nothing out of the ordinary!) In this
situation, I wonder what 'science' would support the 'conventional
wisdom' of using more than the one strand of wire - provided of course
it don't break!


Dunno :-)

In article , Brian Gaff
wrote:
Well, of course I cannot 'see' the graphs, but they do seem to not be
using real world tests, I mean not terminating things an testing
things in isolation..

That is one of the key points which the pdf does not deal with.

More generally, it says nothing about the termination and coupling at
either end of the lengths being compared. Let alone what these might be in
normal use situations.

WRT dogs in the night I can point out two things which strike me about the
graphs of poage 7 of the pdf.

A) That all the mains cables seem to show a common fall in level with
frequency at a rate of around 3dB per 100Mhz.

B) That all the mains cables show variations with frequency that indicate
the presence in the system of a pair of mismatch connectioned spaced 1 or 2
metres apart. (Hard to be precise about the distance as we have no clue as
to the propagation velocities.)

(A) looks like a common mode problem with the measurement system as it
seems doubtful that this variety of cables all show such a similar fall
with frequency.

(B) seems to indicate the the only noticable difference is that the
'PowerKord' cables have a worse match to the source and load than do the
ordinary cables.

Alas, nothing in the pdf tells us if that has any relevance in real use. No
mention is made of what the authors regard as the 'typical' mains socket
source impedance at RF, nor that of a 'typical' PSU. So for all we know, in
real use, the normal cables might reject more RF than the 'PowerKord'
examples if they happened to be a poorer match. The results depend on the
source and load used, and whose values are not specified or justified for
the context.

Hopefully, further details will allow us to assess the measured results.


Slainte,

Jim

--
Please use the address on the audiomisc page 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
Audio Misc http://www.audiomisc.co.uk/index.html

Phil Allison wrote:
"Eiron"
What's the length
'Bout an inch....

and thickness of your single strand of wire?

Real tiny - less than a mm?

Must read the thread more closely. Didn't see the photo.
You've added at least 10 milliohms to one speaker cable.

** Not even that much.

Say the strand is 0.5mm dia and 25 mm long copper.

Works out at only 2.2 milliohms.

Take over 20 amps to make it glow and melt.

The photo looks like an inch of 0.2mm diameter wire from a 79 strand 2.5mm^2 cable.
I think it would blow at less than 20 amps but the voice coil would probably blow first.

--
Eiron.

In article , Rob
wrote:
Jim Lesurf wrote:
In article , Keith G
wrote:

Also from the 'lay POV', I would like to say that the trouble with
these 'snake oil bashing' sessions is that they are never cut and
dried conclusive

Afraid you have missed the point of my posting(s). They are not what
you assert. They are to bring scientifically critical thinking to
assessing a document which is presented by its authors/publishers to
provide a 'scientific' basis for their claims.


Well, yes, and that's fine of course. As a few have pointed out, you are
using up a fair amount of energy before you've questioned the source
(Ben Duncan). Not rocket science, but not a bad place to start on your
critical thought?

The PDF gives a contact. I think I said in an earlier posting that I have
emailed that person asking various questions, and requesting more details.
Since they gave a contact I assumed that was the person they wanted any
questions to be sent to.

BTW I have just this minute had an email in reply from the contact.
That has supplied some more documentation. Not yet had a chance to
look at it, though.

Slainte

Jim

--
Please use the address on the audiomisc page 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
Audio Misc http://www.audiomisc.co.uk/index.html

On 2009-06-21, David Pitt wrote:
Jim Lesurf wrote:

I got my latest copy of 'Stereophile' yesterday and started to read it. I
came across comments by Paul Messenger about some work that Russ Andrews
and Ben Duncan have recently put onto the web. This seems to be taken by
Paul Messenger as showing that Russ's claims re some of his products are
"now supported by proper scientific analysis".

But having looked at

http://www.russandrews.com/downloads...estPremRes.pdf

There appear to be two components to this, do the Russ Andrews mains lead
attenuate mains bourn noise and does mains bourn noise have any effect on
Hi-Fi systems.

It may have been demonstrated that the fancy cables can show some RF
attenuation but it is not demonstrated that this has any effect on sound
quality, that remains just a belief, "RFI is a major pollutant and we
believe that it is one of the major reasons why Hi-Fi systems do not perform
at their best".

Exactly.

I think the paper probably does show that under some circumstances the
Russ Andrews power cords do attenuate interference, and that under some
circumstances RFI can probably be induced to increase the distortion from
a particular amplifier. To me these are not very novel matters.

We are left with the questions of: (i) exactly what are those
circumstances in detail; (ii) whether they are relevant to real life;
and (iii) whether any effects are audible in practice. These seem more
important to me but the paper fails to address them.

However setting my academic curiosity aside I wouldn't think twice before
taking the amount such power cords cost and spending it instead on buying
some music.

I think I have my priorities right.

--
John Phillips

On Mon, 22 Jun 2009 09:51:15 +0100, Jim Lesurf
wrote:

In article , Brian Gaff
wrote:
Well, of course I cannot 'see' the graphs, but they do seem to not be
using real world tests, I mean not terminating things an testing
things in isolation..

That is one of the key points which the pdf does not deal with.

More generally, it says nothing about the termination and coupling at
either end of the lengths being compared. Let alone what these might be in
normal use situations.

WRT dogs in the night I can point out two things which strike me about the
graphs of poage 7 of the pdf.

A) That all the mains cables seem to show a common fall in level with
frequency at a rate of around 3dB per 100Mhz.

B) That all the mains cables show variations with frequency that indicate
the presence in the system of a pair of mismatch connectioned spaced 1 or 2
metres apart. (Hard to be precise about the distance as we have no clue as
to the propagation velocities.)

(A) looks like a common mode problem with the measurement system as it
seems doubtful that this variety of cables all show such a similar fall
with frequency.

(B) seems to indicate the the only noticable difference is that the
'PowerKord' cables have a worse match to the source and load than do the
ordinary cables.

Alas, nothing in the pdf tells us if that has any relevance in real use. No
mention is made of what the authors regard as the 'typical' mains socket
source impedance at RF, nor that of a 'typical' PSU. So for all we know, in
real use, the normal cables might reject more RF than the 'PowerKord'
examples if they happened to be a poorer match. The results depend on the
source and load used, and whose values are not specified or justified for
the context.

Hopefully, further details will allow us to assess the measured results.


Slainte,

Jim

This is all true, but of course all filters (of the non-absorptive
type) work by selective, controlled mismatch. But when that filter is
just a piece of cable, we have a situation where the attenuation is
not only unpredictable, but could quite easily result in an increase
in level when the impedance of the cable is somewhere intermediate
between the source and load impedances. In other words, all you can
say about cables used in this way is that the levels of RF will be
different at the two ends.

The overall slope of the cables (3dB per 100MHz) is about what I would
expect for a cable not designed for the transmission of RF. The
insulation will be pretty lossy, and the unshielded design will allow
a certain amount of radiation,

As to common/differential mode - who knows? Duncan doesn't describe
the experimental setup or the measurement protocol.

d

In article ,
Eiron wrote:
The photo looks like an inch of 0.2mm diameter wire from a 79 strand
2.5mm^2 cable. I think it would blow at less than 20 amps but the voice
coil would probably blow first.

0.2mm diameter is rated at 5 amps in open fuse terms.

Think Jim Lesurf did lots of research into speaker fusing when he was at
Armstrong.

--
*Why are they called apartments, when they're all stuck together? *

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

On 22 Jun, wrote:
In article , Rob

BTW I have just this minute had an email in reply from the contact.
That has supplied some more documentation. Not yet had a chance to
look at it, though.

The contact supplied a document. This doesn't itself answer my questions.
But it did direct me to

http://www.russandrews.com/src/resea...rchpaper09.htm

So I have downloaded the relevant 'papers' from their and will study them.
I'll be interested to see what reactions others may have if they care to do
the same.

Slainte,

Jim

--
Please use the address on the audiomisc page 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
Audio Misc http://www.audiomisc.co.uk/index.html

In article 4a3f51c1.796538671@localhost, Don Pearce
wrote:
[snip]

This is all true, but of course all filters (of the non-absorptive type)
work by selective, controlled mismatch.

Or by circulation or redirection. :-)

But when that filter is just a piece of cable, we have a situation where
the attenuation is not only unpredictable, but could quite easily result
in an increase in level when the impedance of the cable is somewhere
intermediate between the source and load impedances. In other words, all
you can say about cables used in this way is that the levels of RF will
be different at the two ends.

Yes. Thus the need to determine if the conditions of test are appropriate
for normal use situations. The curio for me is that the conditions chosen
show very small levels of (B) for the standard cables. I'd expect that if
the standard cables happened to be almost matched, which is for me a dog
that did not bark. Is that normal, accident, or what?...

Slainte,

Jim

--
Please use the address on the audiomisc page 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
Audio Misc http://www.audiomisc.co.uk/index.html

On Mon, 22 Jun 2009 12:05:39 +0100, Jim Lesurf
wrote:

On 22 Jun, wrote:
In article , Rob

BTW I have just this minute had an email in reply from the contact.
That has supplied some more documentation. Not yet had a chance to
look at it, though.

The contact supplied a document. This doesn't itself answer my questions.
But it did direct me to

http://www.russandrews.com/src/resea...rchpaper09.htm

So I have downloaded the relevant 'papers' from their and will study them.
I'll be interested to see what reactions others may have if they care to do
the same.

Slainte,

Jim

I haven't started reading yet, but I presume that all the equipment in
his entire recording and reproduction chain used the woven power
cables, otherwise the experiment must fail for lack of audible effect.

d