In article , Don
Pearce
wrote:
Jim Lesurf wrote:
A while ago there was some discussion about loudspeaker cables and the
relative merits of analysis using the transmission line and AC lumped
element approachs. I've now done a page on this which people may find
interesting. It is at

http://www.st-andrews.ac.uk/~www_pa/...g/howlong.html


Thanks for that, Jim. Pretty much what I expected, with the (for many
counter-intuitive) result that the high capacitance cable had the
flattest response - the expected result of having a better
characteristic impedance match. Doing the usual maths on your table of
cables

A = 8.5 B = 176 C = 153 D = 59 E = 211 G = 48.76

So as far as top end flatness goes, characteristic impedance is the best
predictor of performance.

That is OK if your concern is well above 20kHz for "top end". However the
actual cable impedances are well away from the approximate values you quote
at or below 20 kHz and the behaviour is better predicted there by series
inductance and resistance than by the above nominal values for
characteristic impedance. As the HFN articles will detail... :-)

Despite high capacitance, which might be
thought of as predicting a sagging top end, the high cap cable (A) at
8.5 ohms impedance is the only cable which is actually flat. And of
course a further implication of this is that this cable does not
present a capacitive load to the amp - it connects the speaker almost
invisibly, presenting the speaker impedance to the amp essentially
unchanged.

I'm afraid you make the classic oversight of assuming behaviour is close to
matched. It simply isn't. The reality is simpler. That low series impedance
gives you the flat response in these sorts of situations when the
frequencies are around 20 kHz or less.


And of course this is for cables of 5 metres. There are many audio apps
that use cable considerably longer than this, which makes it important
to think about the applicability of models.

The interest I have is for domestic audio. I doubt that more than a small
fraction of those use cables an order of magnitude longer than 5 metres.

Slainte,

Jim

--
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In article , Don
Pearce
wrote:
Eiron wrote:
Don Pearce wrote:

Thanks for that, Jim. Pretty much what I expected, with the (for many
counter-intuitive) result that the high capacitance cable had the
flattest response - the expected result of having a better
characteristic impedance match.

You could also say that it is the low inductance cable that has the
flattest response. That's not at all counter-intuitive.



So which are you going to pick, and under what circumstances? Go with
the characteristic impedance and you will be right every time, because
it contains both L and C in the correct proportions.

The results to be published show this is simply incorrect. You would not be
"right every time" to do that.

The problem is that values like the ones you did for characteristic
impedance aren't the right values at audible frequencies, and the actual
value changes with frequency across the audio band. With most LS cables,
most (or all) the audio band is below the R'/L' turnover point.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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In article , Trevor Wilson
wrote:


**Nice work Jim. It backs up what I've been telling people for a couple
of decades. As Phil has stated, what would be interesting would be to
do the same analysis with real-world speakers.

I am creeping up on that. :-) The webpage does show results for 4 - 32
Ohms resistive to indicate that any resistive load value which is broadly
similar to a speaker doesn't change the conclusions much. The page was just
to make the basic point and show the analysis methods.[1] However...

The HFN articles use a series of loads - resistive, capacitive, inductive,
as well as open and short. They compare measurement with theory and get
suprisingly good agreement. I also ended up including things like 'internal
impedance' (aka skin effect) and how it alters the behaviour of cables

I am also in the process of examining the use of squarewaves, and the use
of a load more like a speaker. i.e. one with a complex impedance that has
some peaks and dips.

However for obvious reasons I have broken this up over a series of
articles. All too much for just 3-4 A4 pages! The measurements also took
weeks to do and analyse. The webpage just uses old results by other people,
but I have done my own measurements on various cables, and details should
appear in due course. In fact, there is so much that as with some previous
articles I will probably end up doing 'extended' versions on the web six+
months after the magazine version appears.

FWIW The first HFN article should appear in the next issue. Now seen and
checked a PDF of the page layout. The other articles will appear in
following months, but there will be some breaks and diversions for articles
on other topics.

BTW Although I chose the cables 'at random' from a long list I compiled it
seems clear that 'A' was the old 'Monitor Audio' branded cable claimed to
be '8 Ohm'. For that, the values I have were measured by Jim Moir and
published in HFN. Detailed references in the articles.

Slainte,

Jim

[1] One reason for the webpage is that is will allow me to give it as a
reference if I wish in a magazine article. I wanted readers who are
interested to be able to see the models I used, but to avoid putting 'hard
sums' into the magazine and making the actual article difficult for those
who don't like maths. Given the models anyone else can - if they wish - do
similar work with other loads, cable lengths, etc, etc.

--
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
Audio Misc http://www.audiomisc.co.uk/index.html

Phil Allison wrote:

"Phil Allison"

Jim Lesurf wrote:

http://www.st-andrews.ac.uk/~www_pa/...g/howlong.html

Doing the usual maths on your table of cables

A = 8.5

** Cable "A" would be a woven multi-strand cable like "Tocord" - it was
sold under other names too.

** I have placed a pic of a " Tocord " speaker lead on ABSE - since I
could not find one on the net.

There are 72 green and 72 copper coloured strands - each enamel coated so
are all insulated. There is a central clear plastic core ( not visible in
the pic) of about 4mm diameter which the 144 strands are woven around. The
outer sheath is only 7mm diameter and so the cable is quite flexible.

In order to fit a termination like the banana plugs shown, one must first
burn off the enamel coating with a hot soldering iron and lots of solder.
Quite easy really.

..... Phil

I doubt I'd ever wanna use that Tocord cable.

If someone crushes the cable under a foot or something, then it'd
be easy to get a short between the different colour enamel wires woven
together.
So the amp sees a short circuit. Might be intermittent.
And if the enamel wire can be tinned with a hot soldering iron, then its
fragile enamel,
and softer than grade 2 magnetic winding wire which cannot be cleaned
with a soldering iron and you have to use a
flame or scrape off the enamel with a blade.

But without a short, I can see why the capacitance would be high because
enamel isn't thick insulation,
so wires are close, and closer wires are, the higher C becomes.

Most SS amps are made to tolerate pure C loads from say 0.002uF to 0.22
uf because they have an R+C
series Zobel between output emitters and 0V, and also have an L+R
parallel Zobel between emitters and
output terminal. So at HF above say 20kHz, some pure C isn't ever "seen"
by the output transistors,
so there is no way the C can cause the phase shift and oscillation at
low RF.
But some amps may not be so well designed, eg, like the Flame Linear you
mentioned.

Meanwhile many tube amps are allergic to some pure C load without
speakers connected.
That's why one should always ensure all amps are unconditionally stable
no matter
what the load, or if there is no load.

It used to be fashionable to try to omit the Zobels, to get more
impressive bandwidth,
and to make claims that sound became "unveiled" due to a more direct
connection.
Fashionable ideas are often the purest BS.

A simpler cable can be made by anyone use to blue covered 4 pair Cat 5
cables.
Just twist them together, and make the 8 wires in each become the out
and back wire for the speakers.
Its easy to strip the wires and solder to banana plugs and put some red
and black shrink wrap on.
I know a guy with ESL speakers who likes such cables, and very cheap as
well.
Kinda difficult to get a short if you tread on them.

Patrick Turner.

"Patrick Turner"
"Phil Allison"

Jim Lesurf wrote:

http://www.st-andrews.ac.uk/~www_pa/...g/howlong.html

Doing the usual maths on your table of cables

A = 8.5

** Cable "A" would be a woven multi-strand cable like "Tocord" - it
was
sold under other names too.

** I have placed a pic of a " Tocord " speaker lead on ABSE - since I
could not find one on the net.

There are 72 green and 72 copper coloured strands - each enamel coated
so
are all insulated. There is a central clear plastic core ( not visible in
the pic) of about 4mm diameter which the 144 strands are woven around.
The
outer sheath is only 7mm diameter and so the cable is quite flexible.

In order to fit a termination like the banana plugs shown, one must first
burn off the enamel coating with a hot soldering iron and lots of solder.



I doubt I'd ever wanna use that Tocord cable.


** Look out -

here comes a whole pile of "Turneroid" hypothetical, fabricated drivel !!!


If someone crushes the cable under a foot or something, then it'd
be easy to get a short between the different colour enamel wires woven
together.


** Simply not true.

The strands of enamelled wire are very tough and well protected by the outer
sheath and inner, soft plastic core.


And if the enamel wire can be tinned with a hot soldering iron, then its
fragile enamel,


** That is complete ********.


Most SS amps are made to tolerate pure C loads from say 0.002uF to 0.22
uf because


** And some are not - particularly some UK made hi-fi exotica.

But the problem is easy fixed by adding a small coil in series with the
amplifier's output.

20 turns of 1mm enamel wire wound on a pencil will do.



...... Phil

In article ,
Phil Allison wrote:
And if the enamel wire can be tinned with a hot soldering iron, then
its fragile enamel,


** That is complete ********.

Anyone who tries soldering enamelled wire without first removing the
enamel by other means is a complete pratt. Probably the same type who
would use - or even try such cable for LS use.

--
*Why isn't there a special name for the back of your knee?

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

"Dave Plowman ( ****WIT MORON )"

Phil Allison

And if the enamel wire can be tinned with a hot soldering iron, then
its fragile enamel,


** That is complete ********.

Anyone who tries soldering enamelled wire without first removing the
enamel by other means is a complete pratt.


** ROTFLMAO !!!!!!!!!!!!!!!!!!!!!!!!!!!

YOU are a 100%, total, know nothing ****ing MORON !!

Go look up: " self fluxing polyurethane wire "' sometime.

Designed to be tinned by solder pot dipping or the use of a hot soldering
iron.

You dumb as a dead dog POSTURING POMMY ASS !!!!!!





....... Phil

In article ,
Phil Allison wrote:
Anyone who tries soldering enamelled wire without first removing the
enamel by other means is a complete pratt.


** ROTFLMAO !!!!!!!!!!!!!!!!!!!!!!!!!!!

YOU are a 100%, total, know nothing ****ing MORON !!

Go look up: " self fluxing polyurethane wire "' sometime.

Don't think polyurathene wire would be much use as a conductor, pet

Designed to be tinned by solder pot dipping or the use of a hot
soldering iron.

Everyone keeps a solder pot on the boil, I suppose, my little forensically
challenged colonial.

You dumb as a dead dog POSTURING POMMY ASS !!!!!!

If only you'd learn the Queen's English.

--
*Growing old is inevitable, growing up is optional *

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

"Dave Plowman (News)" wrote:

In article ,
Phil Allison wrote:
And if the enamel wire can be tinned with a hot soldering iron, then
its fragile enamel,

** That is complete ********.

Anyone who tries soldering enamelled wire without first removing the
enamel by other means is a complete pratt. Probably the same type who
would use - or even try such cable for LS use.

But I use enameled wire for winding chokes, and transformers.
The cheap **** from China can be tinned by just persisting with a
soldering iron and flux core,
and its only thin polyurethane enamel. Its softer than the the brown and
green stuff made
with enamel of polyester-imide which you can't tin with a soldering
iron.

Phil loves to say I am complete ********, as we all know, but
using enamel wire for LS cables needs careful thought.

McIntosh used triple insulated enamel wire in bifilar windings for OPT
in tube amps where the two windings wound side by side had a 470Vdc
potential difference.
They lasted OK, so an LS cable should because of low voltages, but then
unlike the varnished wires in an OPT,
the LS wire strands are subject to movement and possible shorts.

Pppl used to plat their own litz wire to make a cable. This avoided skin
effect, and
would keep RF wire resistance low.
Then they'd say it sounded better.

Somehow I think such betterment claims are bollockesque in nature.

Patrick Turner.





--
*Why isn't there a special name for the back of your knee?

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

"Dave Plowman (MORON )"

Phil Allison

Anyone who tries soldering enamelled wire without first removing the
enamel by other means is a complete pratt.


** ROTFLMAO !!!!!!!!!!!!!!!!!!!!!!!!!!!

YOU are a 100%, total, know nothing ****ing MORON !!

Go look up: " self fluxing polyurethane wire "' sometime.


Don't think polyurathene wire would be much use as a conductor, pet


** Go look it up - you despicable arsehole.

Designed to be tinned by solder pot dipping or the use of a hot
soldering iron.

You MORONIC, LYING POMMY ASS !!!!!!





....... Phil