"Jim Lesurf" wrote in message
...
In article om,
wrote:

Laurence Payne wrote:
On Sat, 16 Sep 2006 23:10:04 GMT, Uncopyrightable
wrote:

ok, i don't get it.. I get the bit about use cheap cables, you
all
say the same, what I don't get is how companies can get away
with
selling £40.00+++ pm cable, when you all reckon go cheap. If I
go
cheap is it better to bi-wire? most of the on-line reviews I
have
read say bi-wiring is the best way to go, I am now very
confuzzed.

I quite agree. How DO they get away with it?

No, you don't need to bi-wire. Period.



They get away with it because cables can sound different.

http://www.st-and.demon.co.uk/AudioM.../lscables.html

http://www.st-and.demon.co.uk/AudioM...kracables.html

Slainte,

Jim

--
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html


Having read Jim's files with which I have no arguement, there is
another reason for having a very low cable resistance.

When drive ceases to a loudspeaker cone that is not in its rest
position (we're talking here about LF drivers) its suspension tries to
put it back to the rest position. Inevitably it will overshoot a
little and pass the rest position, so it will oscillate slightly but
in reducing amounts until it stops. During this time the coil is
moving in a magnetic field and so the loudspeaker becomes a generator.

There are two basic reasons that an audio amp has a low output
impedence: one is to follow the time-honoured engineering principle
that the source is low impedence driving a high impedence load; the
second is that the amp 'sees' the energy generated by the loudspeaker
as it settles and must dissipate it and in this instance the amp
output impedence is the load. The lower the amp output impedence the
greater the load it will place on the loudspeaker generator and so the
quicker that generator will die.

If you now put cables of significant resistance in series between the
amp and the loudspeaker-generator the load imposed on the generator
will be reduced and it will take longer to come to rest. The effect of
this is quite audible - the bass tends to sound indistinct and a tad
unreal - 'flappy' or 'flabby' are the usual words. It is thus fairly
safe to say that the larger the loudspeaker cone and the louder you
want to play it, the thicker the cables should be.

Incidently the ratio of the amp output design load - typically 8R - to
the amp output impedence is known as the damping factor. It is normal
to expect a damping factor of at the very least 40 (indicating an amp
output impedence of 0.2R) and more usually 60-80. It can be argued
that going much above this will cause other undesirable effects as
reduction of the output impedence of the amp is often achieved by use
of negative feedback in the amp design which can itself cause audible
artifacts.


--
Woody

harrogate3 at ntlworld dot com

Wally wrote:

Eeyore wrote:

How do you know which is 'better' though. The bi-wire or the single
wire ? It's only a presumption on the part of believers in bi-wiring
based on junk science reasoning that their method is the 'correct'
one !

I'm aware of that. I was assuming that, if there is a change, then it's a
change which brings a technical improvement, in the same way that having
lower resistance cables brings an improvement in technical terms.

There is a very definite interaction between speaker impedance ( which varies
over the audio band ) and cable resistance that affects the frequency response.
The effect is quite small but readily measurable.

The effect is *always* reduced ( i.e. made better ) by using a larger gauge of
wire. The effect of bi-wiring in comparison isn't so straightforward but will
always be inferior to using those same 2 wires in parallel.

Graham

harrogate3 wrote:

It can be argued
that going much above this will cause other undesirable effects as
reduction of the output impedence of the amp is often achieved by use
of negative feedback in the amp design which can itself cause audible
artifacts.

How does negative feedback cause these 'audible artifacts' ?

It's yet another one of those silly myths based on more junk science !

Graham

"harrogate3"

If you now put cables of significant resistance in series between the
amp and the loudspeaker-generator the load imposed on the generator
will be reduced and it will take longer to come to rest. The effect of
this is quite audible - the bass tends to sound indistinct and a tad
unreal - 'flappy' or 'flabby' are the usual words. It is thus fairly
safe to say that the larger the loudspeaker cone and the louder you
want to play it, the thicker the cables should be.


** What ******** - amplifier damping does not relate to cone size or
playing level.

It relates only to the DC resistance of the speaker in use.

The FACT is that connecting cable resistance has barely ANY effect on
speaker damping - since it is in SERIES with the resistance of the
voice coil of the speaker.

The resistance of typical bass speakers is 7 ohms - which INCREASES at
high power levels to possibly 12 ohms or more !!

This increase has the SAME EFFECT on damping as using speaker cables with
** 5 ohms ** resistance !!

Purely due to the temperature coefficient of resistance of copper wire.

Not a single thing you can do about that, short of going to planar or full
range electrostatic designs.


Incidently the ratio of the amp output design load - typically 8R - to
the amp output impedence is known as the damping factor.


** But has NOTHING to do with **electrical damping** as experienced by a
woofer.

Because its own *temperature dependant* resistance IS the DOMINANT factor
in the damping equation.


( Snip even more and worse drivel that must have come from some crackpot's
web site or audiophool rag.)



........ Phil

Jim Lesurf wrote:

In article 1hlsyi2.x7aw5v11xasq9N%wildrover.andy@googlemail. com, Andy
Hewitt wrote:
Wally wrote:


No, it's nothing to do with resistance, it to do with the fact that each
speaker can be moving at different speeds and directions. From this
there is a chance that the woofer can send distortion up the cable and
interfere with the tweeter frequencies.

I don't think you should beleive everything you read in magazines. That
particular theory didn't last IIRC.


You use a thick cable to the LF to send raw power. The tweeter needs a
cleaner signal, so you use a thinner cable for that. By connecting the
cables at source, and separating them at the speaker, there is enough
time to prevent the interference.

Technobbable, I'm afraid. :-)

Thanks Jim, for at least offering a polite response. However, we've
moved on from here a little ;-)

I did actually run a test this morning, but I'm not going to publish my
results here. It'll either end up as a 'told you so, you've wasted your
money' (which I haven't), or 'load of ******** that you can hear a
difference'. So either way, it's a pointless excercise.

--
Andy Hewitt
http://www.thehewitts.eclipse.co.uk/
http://web.mac.com/andrewhewitt1/

In article , harrogate3
wrote:

"Jim Lesurf" wrote in message
...


http://www.st-and.demon.co.uk/AudioM.../lscables.html

http://www.st-and.demon.co.uk/AudioM...kracables.html


Having read Jim's files with which I have no arguement, there is another
reason for having a very low cable resistance.

When drive ceases to a loudspeaker cone that is not in its rest position
(we're talking here about LF drivers) its suspension tries to put it
back to the rest position. Inevitably it will overshoot a little and
pass the rest position, so it will oscillate slightly but in reducing
amounts until it stops. During this time the coil is moving in a
magnetic field and so the loudspeaker becomes a generator.

That is actually included and implicit in the standard argument based on
the input impedance as a function of frequency. It follows from linear
superposition and that the pattern in time is directly related to the
complex frequency response.

There are two basic reasons that an audio amp has a low output
impedence: one is to follow the time-honoured engineering principle that
the source is low impedence driving a high impedence load; the second is
that the amp 'sees' the energy generated by the loudspeaker as it
settles and must dissipate it and in this instance the amp output
impedence is the load. The lower the amp output impedence the greater
the load it will place on the loudspeaker generator and so the quicker
that generator will die.

There is generally an internal series resistance in the speaker system.
This will tend to have a resistance value which is much higher than that of
the cable or most amplifiers. Thus the effect on what people call 'damping'
is generally dominated by this in practice - unless the cables or amp have
'large' impedances - e.g. of the order of an Ohm or more.

If you now put cables of significant resistance in series between the
amp and the loudspeaker-generator the load imposed on the generator will
be reduced and it will take longer to come to rest. The effect of this
is quite audible - the bass tends to sound indistinct and a tad unreal -
'flappy' or 'flabby' are the usual words. It is thus fairly safe to say
that the larger the loudspeaker cone and the louder you want to play it,
the thicker the cables should be.

Incidently the ratio of the amp output design load - typically 8R - to
the amp output impedence is known as the damping factor. It is normal to
expect a damping factor of at the very least 40 (indicating an amp
output impedence of 0.2R) and more usually 60-80. It can be argued that
going much above this will cause other undesirable effects as reduction
of the output impedence of the amp is often achieved by use of negative
feedback in the amp design which can itself cause audible artifacts.

"Damping factor" as quoted in amplifier specs is a bit of a misleading term
for the reasons given above. In reality, the level of motion damping will
tend to be dominated by the internal series resistance of the speaker
system itself.

IIRC Briggs and others showed this both by theory and by measurement about
45 years ago.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Andy Hewitt" wrote in message
news:1hlsyi2.x7aw5v11xasq9N%wildrover.andy@googlem ail.com...

No, it's nothing to do with resistance, it to do with the fact that each
speaker can be moving at different speeds and directions.

They generally are.

From this
there is a chance that the woofer can send distortion up the cable and
interfere with the tweeter frequencies.

So Andy, you're kinda weak on the concept of speaker crossovers?

You use a thick cable to the LF to send raw power.

As if tweeters don't need power?

The tweeter needs a cleaner signal, so you use a
thinner cable for that.

As if thin wire "cleans up" a signal?

By connecting the cables at source, and
separating them at the speaker, there is enough time to prevent the
interference.

As if the time it takes a signal to go down a typical speaker wire is
somehow audibly significant?

On a proper bi-wirable speaker, you actually feed the crossover points
separately, so the signals don't actually mix. If you bridge the
connections, you turn it into an ordinary speaker.

I read an article about this in a pro magazine somewhere, but can't
remember the exact details now, but that was the general gist of it.

Of course whether you can hear the difference or not is a personal
preference.

--
Andy Hewitt
http://www.thehewitts.eclipse.co.uk/
http://web.mac.com/andrewhewitt1/

"Andy Hewitt" wrote in message
news:1hlu2a1.1hpys29194viy3N%wildrover.andy@google mail.com...


http://www.whathifi.com/newsMainTemp...ewssectionID=3


"but we digress - back to the crossover. One of the problems with a standard
crossover is that since one pair of cables carries the signal to and from
the amp, bass signals can tend to swamp the more delicate treble stuff,
especially in the return (or negative) connection back to the amp."

What we see here is drivel swamping out reason. There is no irreversible
mixing of signals in a normal pair of copper speaker wires. The crossover
will separate the woofer and tweeter signals whether or not each section of
the crossover has its own wires going back to the amplifier or not.

"By separating the signal all the way back to amplifier's output stage,
using two runs of cable or a purpose-made four conductor biwire cable, these
effects can be greatly reduced. "

There are no such effects to reduce. Here we see classic snake oil - a
imagainary non-existent effect is made out of whole cloth, and then a more
expensive solution (one that costs real as opposed to imaginary money) is
proposed.


http://www.home-cinema-guide.co.uk/biwire4.htm

"Using two runs of speaker cable allows each crossover to be connected
directly to the amplifier's output stage. The full-frequency signal arrives
at both crossovers through the red/+ conductor and each is filtered so that
the driver receives only the signal it needs.

Note that these two sentences correctly admit that the same full-frequency
signal arrives at both crossovers, even when bi-wiring is used.


" The signals are then passed back to the amp along the corresponding
black/- conductors, but because the high and low frequencies have already
been separated, each has no affect on the other - the delicate treble is not
overpowered by the bass."

Note that the previous two sentences contradict this one, as it says that
there is no separation of the signals.

"Andy Hewitt" wrote in message
news:1hlu6qe.1rrs4gz1d6ve35N%wildrover.andy@google mail.com...

Yes. But this is essentially nothing to do with science. This is to do
with what a listener prefers to hear.

Is that were so, we would only change the listener's mind, not change the
audio system.

If we applied strict physics to a
Hi-Fi, then all the equipment would sound the same anyway.

Simply not so.

In most cases components are made to have a 'sound' by each manufacturer.

Not so. Almost all manufacturers say that their equipment has low distortion
and flat frequency response. That is esentially a claim that their equipment
has no sound of its own, but that it is an accurate reproducer.

This colouration of the audio signal is what we all try to correct using
daft
ideas like spending £500 on interconnects, biwiring and sticking our
Hi-Fi onto concrete mounts.

The imperfections in real-world audio gear are pretty well known. No way can
a randomly-chosen or even a carefully-chosen set of cables "correct" them.

There is no doubt that my system sounds extremely good in its current
configuration. I have yet to try it without biwiring the speakers, but
I'm tempted to do so now.

Whatever floats your boat.

However, there won't be anything scientific
about it, as it'll be my own personal preference that decides whether
one is better than the other or not.

If all you want to do is psych yourself into thinking that your system
sounds better, why not just recite a mantra for several hours?

"APR" wrote in message
...


The only benefit to be seen from bi-wiring is to reduce the resistance of
the wire between amp and speakers.

Biwiring avoids that benefit by hooking the speaker ends of the wires to
different things.

Two sets of wire will have lower resistance then one set of wire.

Only if you hook them in parallel - IOW parallel them at both ends.

As several posters here will state, you can do just as well by strapping
two cores of wire together (parallel) to give twice the cross section of
wire and thus lower resistance.

Actually, paralleling will be better than bi-wiring.

This is only relevant if the core of the wire you are using is not of
adequate cross section for the power being fed to the speakers.

In home hifi, the requirements for copper cross-section are often more
dependent on the impedance curve of the speaker than its power requirements.