Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a few
months ago.

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 Fri, 07 Aug 2009 09:10:40 +0100, Jim Lesurf
wrote:

Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a few
months ago.

Slainte,

Jim

No conclusions section there, but maybe as follows?

1. If you open circuit the cable at the loudspeaker end, it is better
if the cable is somewhat lossy, as this will prevent the quarter wave
Mod Z dropping to too low (potentially damaging) a value.

2. Provided you have a speaker on the far end, none of the cables
result in a particularly problematic load at RF. The minimum impedance
variations tend to come from the cables with lower characteristic
impedance (closest conductor spacing).

3. The Isolda behaves very differently to the rest, and provided it is
used as recommended, presents the most consistent and friendly load of
any.

I could do with some more info on the Isolda cable - what the inductor
is all about and how come the impedance drops so low without it.

d

On 2009-08-07, Don Pearce wrote:
On Fri, 07 Aug 2009 09:10:40 +0100, Jim Lesurf
wrote:

Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a few
months ago.

No conclusions section there, but maybe as follows?

1. If you open circuit the cable at the loudspeaker end, it is better
if the cable is somewhat lossy, as this will prevent the quarter wave
Mod Z dropping to too low (potentially damaging) a value.

Alternatively, perhaps, that a well-designed amplifier will have about
2 uH of good quality inductance in series with its output to avoid such
a case becoming damaging?

--
John Phillips

In article 4a7be630.269829187@localhost, Don Pearce
wrote:
On Fri, 07 Aug 2009 09:10:40 +0100, Jim Lesurf
wrote:

Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a
few months ago.

Slainte,

Jim

No conclusions section there, but maybe as follows?

There are a couple of 'follow on' articles which I wrote a while ago but
are currently unpublished. At present I'm deciding what to do with them.
Put them directly onto the web, or see if a magazine wants them first. When
they appear the 'conclusions' may be a bit clearer.

1. If you open circuit the cable at the loudspeaker end, it is better if
the cable is somewhat lossy, as this will prevent the quarter wave Mod Z
dropping to too low (potentially damaging) a value.

In general, cable losses will reduce the amplitude in the presented
impdance changes with frequency in the RF region. The snag being that if
too large, they could also upset performance in the audio region.

IIUC one aspect of DNM's argument is that his cables do include RF loss.
(My interpretation of what he says is this is due to internal impedance as
the cable uses solid core wire. Thus introducing a loss at RF.)

2. Provided you have a speaker on the far end, none of the cables result
in a particularly problematic load at RF. The minimum impedance
variations tend to come from the cables with lower characteristic
impedance (closest conductor spacing).

Yes, although I'd qualify that as below...

3. The Isolda behaves very differently to the rest, and provided it is
used as recommended, presents the most consistent and friendly load of
any.

I could do with some more info on the Isolda cable - what the inductor
is all about and how come the impedance drops so low without it.

The inductor (and LS end load) are to deal with the loading at RF. If you
look, without these the dips go *very* low. That might upset poor amplifier
designs which don't have unconditional stability, or, say, whose distortion
behaviour could be affected. You'd need to check with Max, but my
understanding is that the networks are included as standard with lengths of
their cable. Although if you know your amp isn't fussed by a severe RF dip
or resonances then I'd say you could dispense with them.

FWIW I like the technical performance of the Isolda. But I'd find it a PITA
to use as you have to take care laying it out, etc. However if you have
very long, essentially straight, cable runs, it should do the job well.

Apart from the above, I've continued to use the Maplin 'monster cable' for
my own systems. But the runs are only a couple of metres.

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 Fri, 07 Aug 2009 10:40:08 +0100, Jim Lesurf
wrote:

In article 4a7be630.269829187@localhost, Don Pearce
wrote:
On Fri, 07 Aug 2009 09:10:40 +0100, Jim Lesurf
wrote:

Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a
few months ago.

Slainte,

Jim

No conclusions section there, but maybe as follows?

There are a couple of 'follow on' articles which I wrote a while ago but
are currently unpublished. At present I'm deciding what to do with them.
Put them directly onto the web, or see if a magazine wants them first. When
they appear the 'conclusions' may be a bit clearer.

1. If you open circuit the cable at the loudspeaker end, it is better if
the cable is somewhat lossy, as this will prevent the quarter wave Mod Z
dropping to too low (potentially damaging) a value.

In general, cable losses will reduce the amplitude in the presented
impdance changes with frequency in the RF region. The snag being that if
too large, they could also upset performance in the audio region.


I can think of certain brand amplifiers which would sing a loud and
shrill song to such a load.

IIUC one aspect of DNM's argument is that his cables do include RF loss.
(My interpretation of what he says is this is due to internal impedance as
the cable uses solid core wire. Thus introducing a loss at RF.)


I can't see that impedance per se introduces loss. Maybe he meant
resistance. Do you suppose he was talking solely about skin effect, or
does he use a particularly lossy dielectric?

2. Provided you have a speaker on the far end, none of the cables result
in a particularly problematic load at RF. The minimum impedance
variations tend to come from the cables with lower characteristic
impedance (closest conductor spacing).

Yes, although I'd qualify that as below...

3. The Isolda behaves very differently to the rest, and provided it is
used as recommended, presents the most consistent and friendly load of
any.

I could do with some more info on the Isolda cable - what the inductor
is all about and how come the impedance drops so low without it.

The inductor (and LS end load) are to deal with the loading at RF. If you
look, without these the dips go *very* low. That might upset poor amplifier
designs which don't have unconditional stability, or, say, whose distortion
behaviour could be affected. You'd need to check with Max, but my
understanding is that the networks are included as standard with lengths of
their cable. Although if you know your amp isn't fussed by a severe RF dip
or resonances then I'd say you could dispense with them.


Ok, I can see that. The inductor is taking the place of the one that
should really already be inside the amplifier. And of course being low
loss and low Z, this cable will invert the high Z speaker resonances
very nicely into an extremely low Z dip. If only speakers were
resistive, we could avoid all this - sigh.

FWIW I like the technical performance of the Isolda. But I'd find it a PITA
to use as you have to take care laying it out, etc. However if you have
very long, essentially straight, cable runs, it should do the job well.

Apart from the above, I've continued to use the Maplin 'monster cable' for
my own systems. But the runs are only a couple of metres.


Same distance here, but I haven't bothered with the sophistication of
Maplin cable. I just use some old wire from the junk box.

d

In article , John Phillips
wrote:
On 2009-08-07, Don Pearce wrote:


1. If you open circuit the cable at the loudspeaker end, it is better
if the cable is somewhat lossy, as this will prevent the quarter wave
Mod Z dropping to too low (potentially damaging) a value.

Alternatively, perhaps, that a well-designed amplifier will have about 2
uH of good quality inductance in series with its output to avoid such a
case becoming damaging?

That is the 'solution' I personally tend to prefer. It also helps deter
entry of RF into the amp via the live speaker lead.

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 4a7cf91f.274676328@localhost, Don Pearce
wrote:
On Fri, 07 Aug 2009 10:40:08 +0100, Jim Lesurf
wrote:


1. If you open circuit the cable at the loudspeaker end, it is better
if the cable is somewhat lossy, as this will prevent the quarter wave
Mod Z dropping to too low (potentially damaging) a value.

In general, cable losses will reduce the amplitude in the presented
impdance changes with frequency in the RF region. The snag being that
if too large, they could also upset performance in the audio region.


I can think of certain brand amplifiers which would sing a loud and
shrill song to such a load.

Would you care to Naim one? :-)

IIUC one aspect of DNM's argument is that his cables do include RF
loss. (My interpretation of what he says is this is due to internal
impedance as the cable uses solid core wire. Thus introducing a loss at
RF.)


I can't see that impedance per se introduces loss. Maybe he meant
resistance. Do you suppose he was talking solely about skin effect, or
does he use a particularly lossy dielectric?

It is difficult to be sure as I've had to 'interpret' his descriptions for
myself. But I think his argument is essentially a mix of things which
include.

A) The cable series inductance and the cable having a high characteristic
impedance. This tends to shove up all the peaks and dips.

b) The internal impedance ('skin effect') adding in higher series
resistance at RF than at audio. So damping the peaks and dips at RF without
affecting audio so much.

FWIW what I did find interesting here is that the mulltistranded cables
also showed signs of internal impedance pushing up the series resistance at
RF. So faith that multistrands suppress internal imedance effects may be
unfounded for - I assume - the simple reason that, usually, there is no
insulation of the individual strands. So the bundles act like a single core
with a rough boundary.

[snip]

Ok, I can see that. The inductor is taking the place of the one that
should really already be inside the amplifier. And of course being low
loss and low Z, this cable will invert the high Z speaker resonances
very nicely into an extremely low Z dip. If only speakers were
resistive, we could avoid all this - sigh.

Yes. Hence my reference back to the 'SCAMP' article. Loudspeaker designers
have a lot to answer for, but rhwy usually chuck the problems onto the lawn
of the amp designers and pretend it is nothing to do with them! 8-]

FWIW I'd have liked to also do results with C and L loadings as they can
give even nastier peaks and dips, dragging them down to lower frequencies.
But I could not find any in time that were sifficiently 'pure single value'
over the range to make the results easy to assess. May return to this in
the far future, though...

Curiously, this was all a nice preparation for some later work on the
claims about mains cables behaving as 'interference filters'. :-)

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 Fri, 07 Aug 2009 12:56:52 +0100, Jim Lesurf
wrote:

Yes. Hence my reference back to the 'SCAMP' article. Loudspeaker designers
have a lot to answer for, but rhwy usually chuck the problems onto the lawn
of the amp designers and pretend it is nothing to do with them! 8-]


All it would take is a 22nF cap in series with 8.2 ohms across the
speaker terminals. A turnover frequency about 1MHz, and virtually no
power to dissipate. That would certainly tame the out-of-band
impedance of your Spendor LS3/5A nicely.

d

"Jim Lesurf Criminal Audiophool Facillitator "


I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a few
months ago.



** Dear UKRA readers,

the religious among us can take some comfort from the fact that

*SATAN* is currently preparing a special blast furnace in HELL

ready to take the putrid soul of one " Jim Leserf " any time soon.

SATAN is very proud of this particular, asinine pommy ****head for
spreading chaos and confusion among the masses.

So he deserves a special reward.


Burn you ****ing *******, burn.




..... Phil

Jim Lesurf wrote:

Hi,

I've just put up a new webpage that provides some measurements on the
properties of a variety of loudspeaker cables. The page is at

http://www.audiomisc.co.uk/HFN/Cables3/TakeTheLead.html

It is an expanded version of the article published in 'Hi Fi News' a few
months ago.

What IDIOT thinks the reactance at 30 MEGAHERTZ has any influence on the
listening experience.

And since when ( Fig 1 for example ) do you run a cable open or shorted as a
valid test ?

WHAT A COMPLETE HEAP OF MINDLESS JUNK !

You should be ashamed of yourself and run some REAL models.

Graham

--
due to the hugely increased level of spam please make the obvious adjustment to
my email address