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View Full Version : Re: Speaker wire - another fine theory


Mike Gilmour
September 4th 03, 04:44 AM
"René" > wrote in message
news:dJo5b.342490$o%2.157128@sccrnsc02...
> Please allow me to introduce (yet) another mechanism of distortion:
>
> Speaker wires can carry substantial AC currents, which in turn
> generate measurable magnetic fields. As the "+" and "-" wires are
> usually positioned side by side, some mechanical forces are working on
> them. The plastic (?) isolator material is somewhat elastic, therefor
> allowing a minimum of relative movement.
>
> This effect is not trivial - with a shorted length of cable and a DC
> current of a few 10's of amps - the motion can actually be felt!

With speakers dipping to one ohm i.e. Apogees driven by the larger Krells
surely this would already have been an area of concern?

> This in turn allows the wires to move respective to one another, and
> by doing so, dissipate a measure of energy.
>
> This obviously leads to a degree of distortion of the signal arriving
> at the speaker.
>
> To come to the point: I do not worry at all about the above effect.

If as you surmise this leads to a degree of distortion then you should be
worried if this is in fact the case.

> Still I would suspect that this effect is notably stronger (and
> perhaps even *measurable*!) than esoteric effects relating to HI-end
> mains cable, or "played-in" interlinks with designated in and outputs.
> It amazes me that this rather obvious effect seems not be discussed in
> hi -end circles. (or is it?)
>
> A *true* High ender is henceforth expected to use loudspeaker wiring
> with spreaders that keeps the conductors well apart lest he will not
> be taken seriously.

Cogan-Hall loudspeaker cable construction was of parallel copper tube
conductors with spreaders approx. every three inches.

> To come to the final point (finally): why are very subtle mechanisms
> of distortion so magnified in the various discussions - and an obvious
> mechanism like described above is scarcely heard off?

Because this is a High End news group where subtle distortions are hopefully
considered important.
I'm sure some cable manufacturer somewhere has already described this effect
in verbose prose already. Wow its too big to ignore - cables actually
moving!

> Disclaimer: if somebody makes money out of this idea - I like to have
> a fair share:-)

Ok do some serious testing then market a speaker cable that is 'motion' free
(take that in its literal sense) then laugh all the way to the bank

;-) Mike

> --
> - René
>

Richard D Pierce
September 4th 03, 04:45 AM
In article <dJo5b.342490$o%2.157128@sccrnsc02>, René > wrote:
>Please allow me to introduce (yet) another mechanism of distortion:
>
>Speaker wires can carry substantial AC currents, which in turn
>generate measurable magnetic fields. As the "+" and "-" wires are
>usually positioned side by side, some mechanical forces are working on
>them. The plastic (?) isolator material is somewhat elastic, therefor
>allowing a minimum of relative movement.
>
>This effect is not trivial - with a shorted length of cable and a DC
>current of a few 10's of amps - the motion can actually be felt!
>
>This in turn allows the wires to move respective to one another, and
>by doing so, dissipate a measure of energy.
>
>This obviously leads to a degree of distortion of the signal arriving
>at the speaker.

Why do you think such a phenomenon would lead to distortion? If
it's dissipating energy, then it will simply increase the
electrical losses in the cable, though by an EXTRAORDINALLY
insiginifcant amount. This is equivalent to adding a TINY amount
of electrical resistance to the cable.

>Still I would suspect that this effect is notably stronger (and
>perhaps even *measurable*!) than esoteric effects relating to HI-end
>mains cable, or "played-in" interlinks with designated in and outputs.
>It amazes me that this rather obvious effect seems not be discussed in
>hi -end circles. (or is it?)

Becasue it is NOT "rather obvious." It's extremely tiny and
wholly insignificant AND if your claim is correct, it's a simple
linear inscrease in resistance.

>A *true* High ender is henceforth expected to use loudspeaker wiring
>with spreaders that keeps the conductors well apart lest he will not
>be taken seriously.

A "high ender" that worried about such an effect would be asking
not to be taken seriously. Simply constraining the cables so
they don't move relative to one another, like most speaker
cables are made, is enough to essentially remder any such effect
irrelevant. SPreading the cables apart has the effect of
ncreasing the inductance of the cable.

>
>To come to the final point (finally): why are very subtle mechanisms
>of distortion so magnified in the various discussions - and an obvious
>mechanism like described above is scarcely heard off?

Because it's not fistorion, it's loss. If you think that's a
problem, simply go one or two gauges heavire in wire, and that
will TOTALLY swamp out ANY such effects.

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |

Stewart Pinkerton
September 4th 03, 04:43 PM
On Wed, 03 Sep 2003 16:33:13 GMT, René > wrote:

>Please allow me to introduce (yet) another mechanism of distortion:
>
>Speaker wires can carry substantial AC currents, which in turn
>generate measurable magnetic fields. As the "+" and "-" wires are
>usually positioned side by side, some mechanical forces are working on
>them. The plastic (?) isolator material is somewhat elastic, therefor
>allowing a minimum of relative movement.
>
>This effect is not trivial - with a shorted length of cable and a DC
>current of a few 10's of amps - the motion can actually be felt!
>
>This in turn allows the wires to move respective to one another, and
>by doing so, dissipate a measure of energy.
>
>This obviously leads to a degree of distortion of the signal arriving
>at the speaker.
>
>To come to the point: I do not worry at all about the above effect.
>
>Still I would suspect that this effect is notably stronger (and
>perhaps even *measurable*!) than esoteric effects relating to HI-end
>mains cable, or "played-in" interlinks with designated in and outputs.
>It amazes me that this rather obvious effect seems not be discussed in
>hi -end circles. (or is it?)

It has been discussed, but as with all other cable-related non-linear
distortions, it has also been quantified at less than -140dB below a
10 amp rms signal, hance hardly of consequence for audio. I *have*
seen microphonic effects in small-signal cables, but that's an
entirely different mechanism, and well understood by those who make
studio-grade microphone cables (as opposed to the 'high end' brands
which just have cable made up by Belden etc.).

>To come to the final point (finally): why are very subtle mechanisms
>of distortion so magnified in the various discussions - and an obvious
>mechanism like described above is scarcely heard off?

Largely because all cables sound the same, so you have to make up
*some* kind of wacky theory to advertise your 'special' brand!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

René
September 4th 03, 06:29 PM
On Thu, 04 Sep 2003 03:45:16 GMT, (Richard D
Pierce) wrote:

>>This obviously leads to a degree of distortion of the signal arriving
>>at the speaker.
>
>Why do you think such a phenomenon would lead to distortion? If=20
>it's dissipating energy, then it will simply increase the=20
>electrical losses in the cable, though by an EXTRAORDINALLY=20
>insiginifcant amount. This is equivalent to adding a TINY amount=20
>of electrical resistance to the cable.
Tiny indeed. But not linear. As actual motion is involved, all kind of
mechanical hysteresis and resonance effects will occur.
>

>>It amazes me that this rather obvious effect seems not be discussed in
>>hi -end circles. (or is it?)
>
>Becasue it is NOT "rather obvious." It's extremely tiny and=20
>wholly insignificant AND if your claim is correct, it's a simple=20
>linear inscrease in resistance.
Not necessarily linear.
>

>Because it's not fistorion, it's loss. If you think that's a=20
>problem, simply go one or two gauges heavire in wire, and that=20
>will TOTALLY swamp out ANY such effects.

As I stated, the effect will be small enough to totally ignore. Yet it
is quantifiable, contrary to effects sometimes contributed to ultra
high cost interlinks / LSP cables and such. My whole point was: "why
zooming in to effects that only (might) occur at homeopathic levels if
a much "bigger" (albeit still extremely insignificant) effect may be
at work"

Or to put it in another way: When striving for total auditive
perfection - attack a problem that does actually (barely...) exist!

(In the mean time I will happily apply solid hobby-store grade wire:-)

--=20
- Ren=E9

Richard D Pierce
September 5th 03, 04:47 PM
In article <ODK5b.264406$cF.83091@rwcrnsc53>, René > wrote:
>On Thu, 04 Sep 2003 03:45:16 GMT, (Richard D
>Pierce) wrote:
>
>>>This obviously leads to a degree of distortion of the signal arriving
>>>at the speaker.
>>
>>Why do you think such a phenomenon would lead to distortion? If=20
>>it's dissipating energy, then it will simply increase the=20
>>electrical losses in the cable, though by an EXTRAORDINALLY=20
>>insiginifcant amount. This is equivalent to adding a TINY amount=20
>>of electrical resistance to the cable.
>Tiny indeed. But not linear. As actual motion is involved, all kind of
>mechanical hysteresis and resonance effects will occur.

No, it does not have "all kinds of mechanical hysteresis."

And since when is resonance a non-linear phenomenon? Is this to
claim that because ALL speakers are resonant, they are, thus,
non-linear? Surely not, as that would be an ansurd assertion.

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |

Stewart Pinkerton
September 7th 03, 03:44 AM
On 6 Sep 2003 14:55:36 GMT, René > wrote:

>On 4 Sep 2003 15:43:43 GMT, (Stewart Pinkerton)
>wrote:
>
>>It has been discussed, but as with all other cable-related non-linear
>>distortions, it has also been quantified at less than -140dB below a
>>10 amp rms signal, hance hardly of consequence for audio. I *have*
>>seen microphonic effects in small-signal cables, but that's an
>>entirely different mechanism, and well understood by those who make
>>studio-grade microphone cables (as opposed to the 'high end' brands
>>which just have cable made up by Belden etc.).
>>
>The -140 dB claim seems realistic to me, and I continue to be
>unworried :-).
>
>Yet, this effect is at least measurable, contrary to some other
>interlink-related effects I have seen mentioned - this places the
>considered effect in a degree of importance an order of magnitude
>higher!
>
>..so what is the cost of rigid coax nowadays...

About a buck a foot. Such 'cable' is standard issue for microwave use,
consisting of a copper tube, a solid copper wire centre conductor, and
solid Teflon dielectric. It's kinda tricky to work with, but it looks
*really* cool! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mike Gilmour
September 7th 03, 07:23 PM
"Stewart Pinkerton" > wrote in message
...
> On 6 Sep 2003 14:55:36 GMT, René > wrote:
>
> >On 4 Sep 2003 15:43:43 GMT, (Stewart Pinkerton)
> >wrote:
> >
> >>It has been discussed, but as with all other cable-related non-linear
> >>distortions, it has also been quantified at less than -140dB below a
> >>10 amp rms signal, hance hardly of consequence for audio. I *have*
> >>seen microphonic effects in small-signal cables, but that's an
> >>entirely different mechanism, and well understood by those who make
> >>studio-grade microphone cables (as opposed to the 'high end' brands
> >>which just have cable made up by Belden etc.).
> >>
> >The -140 dB claim seems realistic to me, and I continue to be
> >unworried :-).
> >
> >Yet, this effect is at least measurable, contrary to some other
> >interlink-related effects I have seen mentioned - this places the
> >considered effect in a degree of importance an order of magnitude
> >higher!
> >
> >..so what is the cost of rigid coax nowadays...
>
> About a buck a foot. Such 'cable' is standard issue for microwave use,
> consisting of a copper tube, a solid copper wire centre conductor, and
> solid Teflon dielectric. It's kinda tricky to work with, but it looks
> *really* cool! :-)

Come on, tell the real truth...its sounds okay ;-)
> --
>
> Stewart Pinkerton | Music is Art - Audio is Engineering

Steve
September 9th 03, 04:45 PM
René > wrote in message news:<dJo5b.342490$o%2.157128@sccrnsc02>...
> Please allow me to introduce (yet) another mechanism of distortion:
>
> Speaker wires can carry substantial AC currents, which in turn
> generate measurable magnetic fields. As the "+" and "-" wires are
> usually positioned side by side, some mechanical forces are working on
> them. The plastic (?) isolator material is somewhat elastic, therefor
> allowing a minimum of relative movement.
>
> This effect is not trivial - with a shorted length of cable and a DC
> current of a few 10's of amps - the motion can actually be felt!
>
> This in turn allows the wires to move respective to one another, and
> by doing so, dissipate a measure of energy.
>
> This obviously leads to a degree of distortion of the signal arriving
> at the speaker.
>
> To come to the point: I do not worry at all about the above effect.
>
> Still I would suspect that this effect is notably stronger (and
> perhaps even *measurable*!) than esoteric effects relating to HI-end
> mains cable, or "played-in" interlinks with designated in and outputs.
> It amazes me that this rather obvious effect seems not be discussed in
> hi -end circles. (or is it?)
>
> A *true* High ender is henceforth expected to use loudspeaker wiring
> with spreaders that keeps the conductors well apart lest he will not
> be taken seriously.
>
> To come to the final point (finally): why are very subtle mechanisms
> of distortion so magnified in the various discussions - and an obvious
> mechanism like described above is scarcely heard off?
>
> Disclaimer: if somebody makes money out of this idea - I like to have
> a fair share:-)

I have encountered this phenomenon examining some twin 10 inch
nearfield monitors in a recording studio. They had been wired with
2.5 mm solid core mains distribution cable. The electromechanical
vibration of the cable was easily felt. Exchanging the cable for a
more conventional multistrand kind produced no obvious change in the
response of the speaker although the cable vibration was no longer
noticable.

Steve Lane

Stewart Pinkerton
September 10th 03, 06:26 PM
On 10 Sep 2003 15:46:50 GMT, (---MIKE---)
wrote:

>Steve, It seems possible that the vibration you felt was transmitted
>directly from the speakers to the solid core wires. I don't think it
>had anything to do with a magnetic effect in the wires especially
>considering that copper has little or no magnetic properties.

Copper wires carrying a current certainly *do* have significant
magnetic proprties. I have seen those properties be sufficient to rip
cables out of a plaster wall in a generating station...............
--

Stewart Pinkerton | Music is Art - Audio is Engineering

---MIKE---
September 10th 03, 11:50 PM
I agree that ANY wire carrying a current has a magnetic field
surrounding it.. What I meant was that the copper itself would not be
magnetized to cause the wire to vibrate.

-MIKE

Rusty Boudreaux
September 11th 03, 05:11 AM
"---MIKE---" > wrote in message
news:6VN7b.408943$YN5.275543@sccrnsc01...
> I agree that ANY wire carrying a current has a magnetic field
> surrounding it.. What I meant was that the copper itself would
not be
> magnetized to cause the wire to vibrate.

Actually, any two wires conducting current regardless of
conductor material will feel a force to due to conservation of
energy. With AC excitation like in a speaker wire the force
between the two wires will pulsate. If you're designing pulsed
energy weapons with millions of amps you have to account for the
forces involved lest your wiring structure rip itself apart. Any
emag textbook will show you how to calculate the forces involved.
As for home speaker wires it's probably on the order of the force
of a gnat fart. Sure it might inject electrons into the signal
from the change in capacitance (conductor spacing) but what's a
few femtoamps when you have amps of signal? Bob Pease did a
paper a few years ago on this relating to measuring very low
input bias current opamps. Motion in the wiring (due to
vibrations in the room) injected enough electrons to mess up the
measurements. Of course, they were trying to measure currents
literally of a few thousand electrons per second. Once current
increases into the picoamp or nanoamp range the effect is not
measureable.

Stewart Pinkerton
September 11th 03, 04:20 PM
On Wed, 10 Sep 2003 22:50:42 GMT, (---MIKE---)
wrote:

>I agree that ANY wire carrying a current has a magnetic field
>surrounding it.. What I meant was that the copper itself would not be
>magnetized to cause the wire to vibrate.

So what? Electromotive force is still generated, which causes the
wires to vibrate.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

ShLampen
September 16th 03, 03:42 PM
In article >, (Stewart
Pinkerton) writes:

>So what? Electromotive force is still generated, which causes the
>wires to vibrate.

I would bet that most of this motion (if any) is caused by the PHYSICAL
vibration of the speaker itself. Are you saying you can feel it at the
amplifier output?

Steve Lampen
Belden Electronics Division

ShLampen
September 16th 03, 03:44 PM
In article >, (Stewart
Pinkerton) writes:

> I *have*
>seen microphonic effects in small-signal cables, but that's an
>entirely different mechanism, and well understood by those who make
>studio-grade microphone cables (as opposed to the 'high end' brands
>which just have cable made up by Belden etc.).
>
Now what does this mean? We make good mic cables for ourself but poor cables
for private labeling? I don't think that's accurate. We've been making cable
for 101 years and microphone cable since electrical recording came in, so I
doubt there's any cable effect we don't know about and take into consideration
with each new design.

Steve Lampen
Belden Electronics Division

Stewart Pinkerton
September 16th 03, 07:25 PM
On 16 Sep 2003 14:42:59 GMT, (ShLampen) wrote:

>In article >, (Stewart
>Pinkerton) writes:
>
>>So what? Electromotive force is still generated, which causes the
>>wires to vibrate.
>
>I would bet that most of this motion (if any) is caused by the PHYSICAL
>vibration of the speaker itself. Are you saying you can feel it at the
>amplifier output?

I'm not saying that it has any *significant* effect whatever, simply
that the effect exists, even if only at the microscopic level. I'm
*certainly* not suggesting that there's any *audible* effect, as I
hope regular readers will understand!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton
September 16th 03, 07:25 PM
On 16 Sep 2003 14:44:33 GMT, (ShLampen) wrote:

>In article >, (Stewart
>Pinkerton) writes:
>
>> I *have*
>>seen microphonic effects in small-signal cables, but that's an
>>entirely different mechanism, and well understood by those who make
>>studio-grade microphone cables (as opposed to the 'high end' brands
>>which just have cable made up by Belden etc.).
>>
>Now what does this mean? We make good mic cables for ourself but poor cables
>for private labeling?

Not what I meant at all, simply that many of the 'high end' brands (as
you well) know, are simply rebadged Belden cable, possibly with the
addition of a fat and colourful outer jacket. I have the greatest
respect for Belden cables, and I apologise if I was unclear on this
point.

> I don't think that's accurate. We've been making cable
>for 101 years and microphone cable since electrical recording came in, so I
>doubt there's any cable effect we don't know about and take into consideration
>with each new design.

I'm sure that's the case, and I've certainly never seen any of the
amazing 'science' quoted by Cardas, MIT et al in the Belden catalogue!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Richard D Pierce
September 16th 03, 08:39 PM
In article >, ShLampen > wrote:
>In article >, (Stewart
>Pinkerton) writes:
>
>>So what? Electromotive force is still generated, which causes the
>>wires to vibrate.
>
>I would bet that most of this motion (if any) is caused by the PHYSICAL
>vibration of the speaker itself. Are you saying you can feel it at the
>amplifier output?

Actually, the force can be calculated.

This is a high-school level physics calculation. I'll avoid the
derivation and simply show that the force between two parallel
conductors carrying a current is calculated as:

F/L = u0/(4 pi) 2I^2/r

where F/L is the force per unit length, u0 is the permability of
free space, close enough for this purpose, I is the current
(and the I^ term assumes that the currents are of equal
magnitude) and r is the distance separating them.

Indeed, the definition of an ampere, the fundamental unit of
current, is in terms of the force between two parallel wires
carrying equal currents:

"An ampere is that constant current which, when flowing in
each of two infinitely long parallel wires that are 2 meter
apart in a vacuum produces a force on each wire of
2*10^-7 newton per meter of length"
Semat, Fundamentals of Physics, Holt, Rinehart &
Winston, 4th ed.

Now, 1 amp is sufficient current to produce 8 watt into a
nominal 8 ohm loudspeaker load, so that gives us a good basis on
which to make some calculations. The separation of the
conductors in a typical 10 gauge zip-cord style speaker wire is
on the order of 5 mm, or 0.005 meters. Since the force on each
goes as the inverse separation, we would expect the force top be
200 times that if the conductors were separated by 1 meter, so
that the total force is:

200 * 2 * 10^-7 newtons/meter

or 4 * 10^-5 newtons/meter per conductor, or a total net force
of 8 * 10^-5 newtons/meter. That's 0.00008 N/m

the force exerted by a 1 gram weight due to the acceleration of
gravity at the earths surface is, (since F = m*a)

F = 0.001 * 9.8 m/sec^2

or 9.8 * 10^-3 newtons. That's 0.0098 N, call is 0.01 N.

Let's put this into perspective. A standard U. S. one cent coin
(a penny) has a mass of 3 grams and weighs in, therefore, at 0.3
newtons. To generate the equivalent force of that 1 ampere
current along 1 meter of wire, we'd have to take that penny,
chop it into about 350 individual pieces, draw each piece
(weighing about 8 micrograms each) into a wire 1 meter long, and
carefully lay it on top of the insulation so that the wire is
compressed under that heavy burden.

Now, using the softest PVC insulation imaginable, let's estimate
its mechanical compliance is on the order of about .1 mm/N/cm of
length, or, thus, about 0.001 mm/N/m of length (just did a VERY
rough measurement). We can now calculate the total displacement
of the conductors in such a wire. simply:

x = F * C

where x is the displacement in meters, F is the applied force in
newtons and c is the mechanical compliance in meters/newton. In
our case, since F = 8 * 10^-5 n/m and C = 10^-6 m/n/m, then

x = 8*10^-5 n * 10^-6 m/n/m

x = 8 * 10^-11 meters

that's 80 TRILLIONTHS of a meter. The radius of a hydrogen atom
is on the order of 10^10 meters, so we're talking about
movements comparable to atomic dimensions for fairly sizeable
currents.

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |

Joseph Oberlander
September 16th 03, 09:34 PM
ShLampen wrote:
> In article >, "Mike Gilmour"
> > writes:
>
>
>>Ok do some serious testing then market a speaker cable that is 'motion' free
>>(take that in its literal sense) then laugh all the way to the bank
>
>
> No, no! Solid concrete speakers. Better yet, build the speakers into the
> foundation for the house (takes multi-room audio to a new level). Of course it
> better be OXYGEN FREE concrete.

Feh. Concrete is for wimps. The real men use cast iron.

Bob-Stanton
September 17th 03, 04:05 PM
"Rusty Boudreaux" > wrote in message >...
> "ShLampen" > wrote in message
> ...
> > In article <gzy5b.260113$cF.82096@rwcrnsc53>,
> (Richard D
> > Pierce) writes:
> > I believe you are wrong here. Inductance is determined by the
> size of the
> > wire, not the distance between them (that would be
> capacitance). I can show
>
> Dude, you need to go back to school. Inductance is proportional
> to the enclosed loop area. Increase the spacing and you increase
> the inductance. Capacitance decreases with separation.
>

I believe it is you, Mr Bordreaux, who needs to go back to school. A
straight wire's inductance will decrease as the diameter increases.

Bob Stanton

Richard D Pierce
September 17th 03, 08:09 PM
In article >,
Bob-Stanton > wrote:
>"Rusty Boudreaux" > wrote in message
>...
>> "ShLampen" > wrote in message
>> ...
>> > In article <gzy5b.260113$cF.82096@rwcrnsc53>,
>> (Richard D
>> > Pierce) writes:
>> > I believe you are wrong here. Inductance is determined by the
>> size of the
>> > wire, not the distance between them (that would be
>> capacitance). I can show
>>
>> Dude, you need to go back to school. Inductance is proportional
>> to the enclosed loop area. Increase the spacing and you increase
>> the inductance. Capacitance decreases with separation.
>>
>
>I believe it is you, Mr Bordreaux, who needs to go back to school. A
>straight wire's inductance will decrease as the diameter increases.

Double dude, go back to reading class, that's NOT what we are
talking about at all.

We are talking about the effective series inductance of a
LOOP. In other words. Take a speaker wire, with its two
conductors. Measure the inductance of the whole shebang. Now,
separated the two conductors of the speaker wire by a large
distance, say, insted of them being 5 mm apart and in parallel,
separate them so that they now are 1 meter apart save where they
connect to the amp and speaker. Measure the inductance.

It will be different. How?

(Hint: inductance is a function of enclosure loop area, which we
just changed by a whole bunch).

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |

Rusty Boudreaux
September 18th 03, 04:19 AM
"Bob-Stanton" > wrote in message
...
> "Rusty Boudreaux" > wrote in message
> > Dude, you need to go back to school. Inductance is
proportional
> > to the enclosed loop area. Increase the spacing and you
increase
> > the inductance. Capacitance decreases with separation.
> >
>
> I believe it is you, Mr Bordreaux, who needs to go back to
school. A
> straight wire's inductance will decrease as the diameter
increases.

Bob Sattnon,

How about actually reading what we are discussing.

Steve Lampen (ShLampen) made two assertions:

"Inductance is determined by the size of the wire, not the
distance between them (that would be capacitance)."

and

"Speading out each conductor is one way to reduce inductance."

His first assertion was wrong and the second was actually
backward (assuming he meant spreading instead of speading). I
corrected both of his assertions by pointing out increasing the
SPACING and thus increasing the loop area will increase the
inductance.

Did I, at any point, say anything about the wire diameter? But
since you brought it up, which effect is more pronounced? Take a
typical speaker wire and double the conductor diameter while
keeping the separation between the two the same. Now take the
original wire and increase the spacing by one conductor diameter
(i.e. the center of the conductors will be at the same location
as the case with larger diameter wire). Now, which case (bigger
wire or more separation) has a larger inductance?

Stewart Pinkerton
September 18th 03, 03:36 PM
On Wed, 17 Sep 2003 18:09:09 GMT, (Bob-Stanton)
wrote:

(Stewart Pinkerton) wrote in message
>
>> Goertz
>> MI has very low impedance, around 6-8 ohms, and very high capacitance,
>> while the classic spaced construction cable, 'balanced' FM antenna
>> feeder, has 300 ohm impedance and very high inductance. Agreed that
>> we're talking a lot less than milliHenries here.
>
>Actually, if the Goertz cable (or any other) is terminated in it's
>characteristic impedance, it will not look capacitive or inductive to
>the amplifier. It's terminal impedance will be a pure resistance.

Yes, but that isn't ever going to happen with a loudspeaker, except at
a very few specific frequencies.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton
September 18th 03, 03:36 PM
On 18 Sep 2003 02:47:05 GMT, (Johnd1001) wrote:

>Dick is, of course, quite right.
>
>It never seems to surprise me how many persons, perhaps with the best
>intentions but with questionable technical credentionals, insist on logging on
>and posting what is little more than technical nonsense.
>
>How sad for both them and audiophiles who do not know who or what to believe.

It doesn't usually take very long to establish what are the real facts
around here! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Bob-Stanton
September 18th 03, 03:45 PM
(Richard D Pierce) wrote in message

> Double dude, go back to reading class, that's NOT what we are
> talking about at all.
>

I must confess, I'm *guilty as charged*.I didn't read the message
carefully enough. (However, my statement was technically correct. The
inductance of a single straight wire does decrease as the wire
diameter increases.)

However *you* are also guilty of not reading carefully. The subject
was a transmission line (speaker cable) *not a loop of copper wire*. A
transmission line is two conductors in parrallel, with a termination
at the end. The termination can be any impedance. *Only* if the
termination is a short, will the speaker cable have the
characteristics of a wire 'loop'. If the termination is an 'open', the
line (at audio frequencies) will look like a capacitor. If the
terminated is a resistor (of the correct impedance), the line will
look resistive to the amplifier (not inductive or capacitive).

As the spacing between the two parallel conductors increases, the
capacitance between the two conductors decreases, but the inductance
of each conductor *remains the same*. Only if the termination is a
short, does the loop inductance increase.

Bob Stanton

Don Pearce
September 18th 03, 05:14 PM
On 18 Sep 2003 14:36:22 GMT, (Stewart Pinkerton)
wrote:

>On Wed, 17 Sep 2003 18:09:09 GMT, (Bob-Stanton)
>wrote:
>
(Stewart Pinkerton) wrote in message
>>
>>> Goertz
>>> MI has very low impedance, around 6-8 ohms, and very high capacitance,
>>> while the classic spaced construction cable, 'balanced' FM antenna
>>> feeder, has 300 ohm impedance and very high inductance. Agreed that
>>> we're talking a lot less than milliHenries here.
>>
>>Actually, if the Goertz cable (or any other) is terminated in it's
>>characteristic impedance, it will not look capacitive or inductive to
>>the amplifier. It's terminal impedance will be a pure resistance.
>
>Yes, but that isn't ever going to happen with a loudspeaker, except at
>a very few specific frequencies.

True, but using a decent 8-ohm cable even with a real speaker will
yield an impedance (forgetting the speaker itself) that is very, very
close to a resistive 8 ohms. It certainly will not be the highly
inductive load of a traditional twin-flex speaker cable. Of course
some amplifiers need that additional inductive load to stay stable,
but that is another story.

d

_____________________________

http://www.pearce.uk.com

Bob-Stanton
September 18th 03, 07:01 PM
"Rusty Boudreaux" > wrote in message news:<gv9ab.489808

> How about actually reading what we are discussing.
>
> Steve Lampen (ShLampen) made two assertions:
>
> "Inductance is determined by the size of the wire, not the
> distance between them (that would be capacitance)."
>
> and
>
> "Speading out each conductor is one way to reduce inductance."
>
> His first assertion was wrong and the second was actually
> backward (assuming he meant spreading instead of speading). I
> corrected both of his assertions by pointing out increasing the
> SPACING and thus increasing the loop area will increase the
> inductance.
>
> Did I, at any point, say anything about the wire diameter?

Lampen was referring to the 'size' of the wire. That is diameter or
gage, right?

> But
> since you brought it up, which effect is more pronounced? Take a
> typical speaker wire and double the conductor diameter while
> keeping the separation between the two the same. Now take the
> original wire and increase the spacing by one conductor diameter
> (i.e. the center of the conductors will be at the same location
> as the case with larger diameter wire). Now, which case (bigger
> wire or more separation) has a larger inductance?

In the first case, doubling the diameter of speaker wire would reduce
the loop inductance.

In the second case, doubling the wire spacing would increase the loop
inductance.

In the a real world both you and Lampen are wrong. Real speaker
cables typically have a 75 Ohms characteristic impedance. This is true
for both large and small gage cables. The characteristic impedance is
a function of the ratio of the wire's inducatance and capacitance, not
it's absolute size.

A large speaker cable (12 gage) will typically have a characteristic
impedance of 75 to 120 Ohms. If an 8 Ohm termination is connected to
the end of a 20 ft long, 12 gage speaker cable, the impedance that the
amplifier will see (at 20KHz) will be 8.096 + j 0.189. A 20 gage
speaker cable (of the same 75 Ohms characteristic impedance) will have
an impedance 8.196 +j 0.189. The resistive component of the impedance
of the small speaker cable, will be slightly higher, but the inductive
component will be exactly the same. Therefore both large and small
speaker cables, can have the same inductance.

So, if you are saying a larger gage speaker will always have more
inductance, you are wrong (sorry). Lampen was also wrong when he said
it would have less inductance.

Bob Stanton

Stewart Pinkerton
September 19th 03, 05:32 PM
On 18 Sep 2003 16:14:04 GMT, Don Pearce > wrote:

>On 18 Sep 2003 14:36:22 GMT, (Stewart Pinkerton)
>wrote:
>
>>On Wed, 17 Sep 2003 18:09:09 GMT, (Bob-Stanton)
>>wrote:
>>
(Stewart Pinkerton) wrote in message
>>>
>>>> Goertz
>>>> MI has very low impedance, around 6-8 ohms, and very high capacitance,
>>>> while the classic spaced construction cable, 'balanced' FM antenna
>>>> feeder, has 300 ohm impedance and very high inductance. Agreed that
>>>> we're talking a lot less than milliHenries here.
>>>
>>>Actually, if the Goertz cable (or any other) is terminated in it's
>>>characteristic impedance, it will not look capacitive or inductive to
>>>the amplifier. It's terminal impedance will be a pure resistance.
>>
>>Yes, but that isn't ever going to happen with a loudspeaker, except at
>>a very few specific frequencies.
>
>True, but using a decent 8-ohm cable even with a real speaker will
>yield an impedance (forgetting the speaker itself) that is very, very
>close to a resistive 8 ohms.

No, it won't. Anyone who has dabbled in radio will tell you that you
need at least tolerably close load matching to get anything like a
proper resistive transmission line. Now, since the amplifier certainly
won't have anywhere close to 8 ohms source impedance, and the speaker
won't be anywhere near to an 8 ohm resistive load over the vast
majority of its working range, you are in fact back to the lumped
capacitance model.

> It certainly will not be the highly
>inductive load of a traditional twin-flex speaker cable. Of course
>some amplifiers need that additional inductive load to stay stable,
>but that is another story.

A reality check will indicate that a few dozen microHenries (as you'd
get for ten feet of 'zipcord') hardly constitutes a 'highly inductive
load', even at 20kHz.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton
September 19th 03, 05:32 PM
On 18 Sep 2003 14:45:08 GMT, (Bob-Stanton)
wrote:

>The subject
>was a transmission line (speaker cable) *not a loop of copper wire*. A
>transmission line is two conductors in parrallel, with a termination
>at the end. The termination can be any impedance. *Only* if the
>termination is a short, will the speaker cable have the
>characteristics of a wire 'loop'. If the termination is an 'open', the
>line (at audio frequencies) will look like a capacitor. If the
>terminated is a resistor (of the correct impedance), the line will
>look resistive to the amplifier (not inductive or capacitive).
>
>As the spacing between the two parallel conductors increases, the
>capacitance between the two conductors decreases, but the inductance
>of each conductor *remains the same*. Only if the termination is a
>short, does the loop inductance increase.

While this is all true, the reality is that most speaker cables have a
characteristic impedance of 50-100 ohms, and are connected to a load
of less than 8 ohms driven from a source of less than 1 ohm. To a
close approximation, this *is* a shorted termination.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Don Pearce
September 19th 03, 06:53 PM
On 19 Sep 2003 16:32:15 GMT, (Stewart Pinkerton)
wrote:

>On 18 Sep 2003 16:14:04 GMT, Don Pearce > wrote:
>
>>On 18 Sep 2003 14:36:22 GMT, (Stewart Pinkerton)
>>wrote:
>>
>>>On Wed, 17 Sep 2003 18:09:09 GMT, (Bob-Stanton)
>>>wrote:
>>>
(Stewart Pinkerton) wrote in message
>>>>
>>>>> Goertz
>>>>> MI has very low impedance, around 6-8 ohms, and very high capacitance,
>>>>> while the classic spaced construction cable, 'balanced' FM antenna
>>>>> feeder, has 300 ohm impedance and very high inductance. Agreed that
>>>>> we're talking a lot less than milliHenries here.
>>>>
>>>>Actually, if the Goertz cable (or any other) is terminated in it's
>>>>characteristic impedance, it will not look capacitive or inductive to
>>>>the amplifier. It's terminal impedance will be a pure resistance.
>>>
>>>Yes, but that isn't ever going to happen with a loudspeaker, except at
>>>a very few specific frequencies.
>>
>>True, but using a decent 8-ohm cable even with a real speaker will
>>yield an impedance (forgetting the speaker itself) that is very, very
>>close to a resistive 8 ohms.
>
>No, it won't. Anyone who has dabbled in radio will tell you that you
>need at least tolerably close load matching to get anything like a
>proper resistive transmission line. Now, since the amplifier certainly
>won't have anywhere close to 8 ohms source impedance, and the speaker
>won't be anywhere near to an 8 ohm resistive load over the vast
>majority of its working range, you are in fact back to the lumped
>capacitance model.
>
I do mean close. With the line being a minute fraction of a wavelength
long, You would be very hard pressed to measure the speaker alone as
any different to the speaker plus line (once the line delay has been
normalised) even at the frequencies where the speaker is quite some
way from 8 ohms. Normal speaker cables, around a couple of hundred
ohms, can make a measurable difference - a fact attested to by the
instability of some amplifiers using them

What I am really trying to do here is dispel the myth that such cables
(like the Goertz) are in some way capacitive when driving a speaker.
The fact is they aren't.

>> It certainly will not be the highly
>>inductive load of a traditional twin-flex speaker cable. Of course
>>some amplifiers need that additional inductive load to stay stable,
>>but that is another story.
>
>A reality check will indicate that a few dozen microHenries (as you'd
>get for ten feet of 'zipcord') hardly constitutes a 'highly inductive
>load', even at 20kHz.

Inductive enough to pull a poor amplifier back from the brink of
oscillation, though.

d

_____________________________

http://www.pearce.uk.com

Stewart Pinkerton
September 20th 03, 04:12 PM
On 19 Sep 2003 17:53:15 GMT, Don Pearce > wrote:

>On 19 Sep 2003 16:32:15 GMT, (Stewart Pinkerton)
>wrote:

>>Anyone who has dabbled in radio will tell you that you
>>need at least tolerably close load matching to get anything like a
>>proper resistive transmission line. Now, since the amplifier certainly
>>won't have anywhere close to 8 ohms source impedance, and the speaker
>>won't be anywhere near to an 8 ohm resistive load over the vast
>>majority of its working range, you are in fact back to the lumped
>>capacitance model.
>>
>I do mean close. With the line being a minute fraction of a wavelength
>long, You would be very hard pressed to measure the speaker alone as
>any different to the speaker plus line (once the line delay has been
>normalised) even at the frequencies where the speaker is quite some
>way from 8 ohms.

Well yes, due to the 'line' being a very small fraction of a
wavelength, as you say.

> Normal speaker cables, around a couple of hundred
>ohms, can make a measurable difference - a fact attested to by the
>instability of some amplifiers using them

That is due to the series inductance of the cable, not the
characteristic impedance per se. Stick a milliHenry inductor on the
front of some 8-ohm Goertz MI, and you get the same result.

>What I am really trying to do here is dispel the myth that such cables
>(like the Goertz) are in some way capacitive when driving a speaker.
>The fact is they aren't.

The fact is, they are. Try hooking an original Naim NAP250 to some
Goertz MI, and watch it fry!

>>> It certainly will not be the highly
>>>inductive load of a traditional twin-flex speaker cable. Of course
>>>some amplifiers need that additional inductive load to stay stable,
>>>but that is another story.
>>
>>A reality check will indicate that a few dozen microHenries (as you'd
>>get for ten feet of 'zipcord') hardly constitutes a 'highly inductive
>>load', even at 20kHz.
>
>Inductive enough to pull a poor amplifier back from the brink of
>oscillation, though.

Yes, as noted above.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Bob-Stanton
September 20th 03, 04:15 PM
(Stewart Pinkerton) wrote in message

> While this is all true, the reality is that most speaker cables have a
> characteristic impedance of 50-100 ohms, and are connected to a load
> of less than 8 ohms driven from a source of less than 1 ohm. To a
> close approximation, this *is* a shorted termination.

But Dick made the *general statement* that as the spacing increases,
the inductance increases. This is not always true.

For example, if the cable has a characteristic impedance of 4 Ohms,
and if the loudspeaker load is 8 Ohms, the amplifier will see a
resistive /capacitve load.

For the above case, 20 ft of cable, at 20 kHz, would be 7.98 -j 0.031
Ohms. If the wires are seporated a little, the cable's input impedance
becomes *less capacitive*, not more inductive. One can *not* make the
general statement, that as speaker wires are seporated they become
more inductive.

The problem comes from trying to look at a transmission line as lumped
constants. Let me give you a challenge. I understand that ordinary zip
cord has a characteristic impedance of 50 Ohms. Using lumped
constants, tell me what is the input impedance of 20 ft of (16 gage)
zip cord, terminated by an 8 Ohm resistor.

Bob Stanton

Bob-Stanton
September 20th 03, 05:56 PM
(Stewart Pinkerton) wrote in message >...
> On 18 Sep 2003 16:14:04 GMT, Don Pearce > wrote:
>
> >On 18 Sep 2003 14:36:22 GMT, (Stewart Pinkerton)
> >wrote:
> >
> >>On Wed, 17 Sep 2003 18:09:09 GMT, (Bob-Stanton)
> >>wrote:
> >>
> (Stewart Pinkerton) wrote in message
> >>>

>
> No, it won't. Anyone who has dabbled in radio will tell you that you
> need at least tolerably close load matching to get anything like a
> proper resistive transmission line.

That is because at RF, the cable is usually many wavelengths long. A
cable will act as an impedance transformer, if the load is other than
the cable's characteristic impedance.

As for audio, a 20 ft long cable is only 406 E-6 wavelengths long (at
20 kHz). This is far too short to cause an impedance transformation.
Therefore, the impedance seen by the amplifier will be nearly the same
as the impedance of the load (loudspeaker). A cable will add a tiny
amount of resistance and inductance, but that will usually be
insignificant.

> Now, since the amplifier certainly
> won't have anywhere close to 8 ohms source impedance, and the speaker
> won't be anywhere near to an 8 ohm resistive load over the vast
> majority of its working range, you are in fact back to the lumped
> capacitance model.
>

Trying to analyze a transmission line, (even a short one like an audio
cable) by using lumped constants, will always result in wrong answers.

Bob Stanton

Stewart Pinkerton
September 21st 03, 04:36 PM
On 20 Sep 2003 15:15:37 GMT, (Bob-Stanton)
wrote:

(Stewart Pinkerton) wrote in message
>
>> While this is all true, the reality is that most speaker cables have a
>> characteristic impedance of 50-100 ohms, and are connected to a load
>> of less than 8 ohms driven from a source of less than 1 ohm. To a
>> close approximation, this *is* a shorted termination.
>
>But Dick made the *general statement* that as the spacing increases,
>the inductance increases. This is not always true.
>
>For example, if the cable has a characteristic impedance of 4 Ohms,
>and if the loudspeaker load is 8 Ohms, the amplifier will see a
>resistive /capacitve load.

There is however no such cable on the market, and that would in any
event be an absolutely extreme construction of no sonic merit in
almost all situations (long runs into certain electrostats being the
only exception). Indeed, the *only* occasion when such a cable would
make any kind of sense, is precisely in that situation where the load
is *less* than the characteristic imepadnece of the cable at high
frequencies.

>For the above case, 20 ft of cable, at 20 kHz, would be 7.98 -j 0.031
>Ohms. If the wires are seporated a little, the cable's input impedance
>becomes *less capacitive*, not more inductive. One can *not* make the
>general statement, that as speaker wires are seporated they become
>more inductive.

One can, for normal constructions of two spaced conductors.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Bob-Stanton
September 24th 03, 05:55 PM
(Stewart Pinkerton) wrote in message >...
> On 22 Sep 2003 22:30:59 GMT, (Bob-Stanton)
> wrote:
>
> (Stewart Pinkerton) wrote in message >...
> >> On 20 Sep 2003 15:15:37 GMT, (Bob-Stanton)
> >> wrote:
> >>
> >> (Stewart Pinkerton) wrote in message
> >> >

> >
> >As I recall, Dunlavy rated his ribbon cable as 6 Ohms characteristic
> >impedance. That cable would have a slightly capacitive loop impedance
> >with an 8 Ohm load.
>
> Indeed he did, and the Dunlavy cable was/is probably the most
> *technically* excellent speaker cable ever made. OTOH, John Dunlavy
> also noted that it was audibly indistinguishable from 'zipcord', even
> on his top studio monitors (which were 4-6 Ohm loads).

Yes, I agree. You will notice I *never* said 6 Ohm ribbon cable
sounded better than zip cord. (In this thread I was writing about how
the inductance of cable changes with spaceing, not how various cables
sound.)

Most people would be *better off* with zip cord than with expensive
ribbon cable. Many amplifier designs include a small inductor in the
output. This inductance improves stability. Zip cord is slightly more
inductive than ribbon cable, which is an advantage not a disadvantage.

Bob Stanton

Dick Pierce
September 24th 03, 07:07 PM
(Bob-Stanton) wrote in message >...
> "Rusty Boudreaux" > wrote in message news:<gv9ab.489808
>
> > How about actually reading what we are discussing.
> >
> > Steve Lampen (ShLampen) made two assertions:
> >
> > "Inductance is determined by the size of the wire, not the
> > distance between them (that would be capacitance)."
> >
> > and
> >
> > "Speading out each conductor is one way to reduce inductance."
> >
> > His first assertion was wrong and the second was actually
> > backward (assuming he meant spreading instead of speading). I
> > corrected both of his assertions by pointing out increasing the
> > SPACING and thus increasing the loop area will increase the
> > inductance.
> >
> > Did I, at any point, say anything about the wire diameter?
>
> Lampen was referring to the 'size' of the wire. That is diameter or
> gage, right?

Mr. Stanton, please read the quote above:

"Inductance is determined by the size of the wire, not the
distance between them (that would be capacitance)."

"Speading out each conductor is one way to reduce inductance."

He was talking, as is quite apparent about both: he was making a claim
that the inductance was dependent upon conductor diameter, something
no on has denied, AND he also claimed that separating the two conductors
in a speaker wire has no effect on inductance, which is provably wrong
both theoretically and empirically.

Johnd1001
October 3rd 03, 11:08 PM
I agree, entirely, with Bob:s observations.

John Dunlavy )