I have read more than one article where the recommended maximum length
of loudspeaker wire is presented as a function of the wire gauge and
the impedance of the speakers, e.g. in the Wikipedia article

http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge

I have also heard that output power and damping factor should be
considered as well - a high power amplifier needs a thicker cable.

Are there any studies made about the wire length contra output power and
damping factor?


/August

On Oct 15, 2:38=A0pm, August Karlstrom <fusionf...@gmail.com> wrote:
> I have read more than one article where the
> recommended maximum length of loudspeaker
> wire is presented as a function of the wire gauge and
> the impedance of the speakers, e.g. in the Wikipedia
> article
>
> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>
> I have also heard that output power and damping factor
> should be considered as well - a high power amplifier
> needs a thicker cable.
>
> Are there any studies made about the wire length
> contra output power and damping factor?

First, ignore most if not all claims you see about
damping factor. It's a feel-good specification that
except in the most pathological cases, has essentially
no meaning whatsoever, despite the occasional
protestations you see to the contrary.

Second, check out:

www.cartchunk.org/audiotopics

and click on the link labeled "Damping Factor:
Effects on System Response," for the reason why
damping factor is a useless measure.

As to the fact that bigger amplifiers need heavier
wire, while this may be true when you're buying
extension cords to run power equipment and effects
such as ohmic losses and heating in a 100-foot
cable and resulting the voltage drop at 25 or 30 or
more amps IS significant, 25 or 30 amps into
an 8 ohm speaker correspond to 5000 to 7200
watts. Hardly a situation even remotely possible in
a home high fidelity system.

By the way, the ultimate limit, as defined by the
fusing current, i.e., the temperature at which the
wire fails due to excessive temperature (it melts),
for 14 gauge copper is listed as 140 amperes. Into
an 8-ohm speaker, that represents 156,800 watts.

In other words, for PRACTICAL application, no,
higher power amps DO NOT require thicker cables
once you get below the 16-gauge realm.

For runs up to 25 feet, any good quality 14-gauge
speaker wire quite appropriate. 14 gauge copper
twin-lead speaker cable has an effective DC
resistance of about 0.005 ohms per foot. 25 feet
gives you a total resistance of 0.125. If you have
already read the articale I cited above, you would
know' that for a typical 8-ohm speaker, this lowers
the electrical damping of the system by a measely
2%: having far less an effect on your speaker's
response than changing humidity temperature or,
for that matter, slight movements of your head
when listening.

The comments in the Wiki article suggesting that
silver has a lower resistance than copper, while
true, are simply irrelevant. Yes, a 14 gauge silver
cable 25 feet long will have a total resistance of
0.118 ohms vs 0.125 ohms for copper: that's less
than a 10% difference. FOr a price FAR lower than
upgrading from 14 gauge copper to 14 gauge silver
wire, you can upgrade, if you really think it's
important from 14 gauge copper to 12 gauge
copper and drop the total resistance not by
a mere 9%, but by nearly 40%. That drop will,
by the way, change the loss of electrical damping'
on the speaker from 2% down to about 1.3%. Big
deal.

[Again, posting from google waiting for my nntp
server to come back on line]

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

"August Karlstrom" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)

> I have read more than one article where the recommended
> maximum length of loudspeaker wire is presented as a
> function of the wire gauge and the impedance of the
> speakers, e.g. in the Wikipedia article
>
> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge

I chased the footnotes for this paper, and found that it was heavily based
on this paper:

http://procosound.com/download/white...r%20Cables.pdf

Proco Sound is a well-known supplier to the professional audio and in
particular the live sound industry. In general the acccuracy requirements
for live sound are somewhat relaxed as compared to high-accuracy home or
mastering/mixing room audio. The Wikipedia article wire length
recommendations seem to be based on maintaining a damping factor of about 20
which again is somewhat relaxed as compared to the requirements for high
performance audio. I would recomment using a criteria of maintaining the
damping factor between 50 and 100.

> I have also heard that output power and damping factor
> should be considered as well - a high power amplifier
> needs a thicker cable.

Generally speaking, sizing wire for a good damping factor will result in
adequate capacitor for the kinds of power amps generally used for home
audio.

> Are there any studies made about the wire length contra
> output power and damping factor?

Yes. The Greiner JAES paper is a classic and covers other issues. If the
speakers being used have unusually variable and low impecance curves then
the resistance and inductance of the speaker cable become more signficant.

"August Karlstrom" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I have read more than one article where the recommended maximum length
> of loudspeaker wire is presented as a function of the wire gauge and
> the impedance of the speakers, e.g. in the Wikipedia article
>
> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge

**Like all such cliams, the Wiki article over-simplifies things. They ignore
the very real effects of inductance, when using long cable runs and speakers
which exhibit a falling impedance at HF (like ESLs). In those cases, the
inductive effects of cable can become quite significant.

>
> I have also heard that output power and damping factor should be
> considered as well - a high power amplifier needs a thicker cable.

**Again, it depends on the speakers and the length of the cable.

>
> Are there any studies made about the wire length contra output power and
> damping factor?

**It's just maths. There's no real mystery here. The problem with the term
'damping factor' is that it relates to (usually) an 8 Ohm impedance. Hardly
any loudspeakers present an 8 Ohm impedance. A far better term for amplifier
manufacturers to use is output impedance vs. frequency. IOW: The output
impedance should always be specified from 20Hz ~ 20kHz. Many SET and Class D
amplifier manufacturers carefully avoid citing this data for some very good,
albeit cynical, reasons. The output impedance of such amplifiers can easily
reach several Ohms at 20kHz.


--
Trevor Wilson
www.rageaudio.com.au

On 2010-10-17 03:17, Trevor Wilson wrote:
> "August Karlstrom"<(E-Mail Removed)> wrote in message
>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>
> **Like all such cliams, the Wiki article over-simplifies things. They ignore
> the very real effects of inductance, when using long cable runs and speakers
> which exhibit a falling impedance at HF (like ESLs). In those cases, the
> inductive effects of cable can become quite significant.

To take my example again, let's say I need a pair of cables, each four
meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
wire would be insufficient?

Several people in this newsgroup believe that all wire sounds the same
provided it is of the "correct type". What I'm trying to find out here
is what the correct type is. I am not so interested in general claims
that cannot be used in practice to make decisions.

Thanks for the input.


/August

On Sun, 17 Oct 2010 06:54:25 -0700, August Karlstrom wrote
(in article <(E-Mail Removed)>):

> On 2010-10-17 03:17, Trevor Wilson wrote:
>> "August Karlstrom"<(E-Mail Removed)> wrote in message
>>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>>
>> **Like all such cliams, the Wiki article over-simplifies things. They ignore
>> the very real effects of inductance, when using long cable runs and speakers
>> which exhibit a falling impedance at HF (like ESLs). In those cases, the
>> inductive effects of cable can become quite significant.
>
> To take my example again, let's say I need a pair of cables, each four
> meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
> wire would be insufficient?
>
> Several people in this newsgroup believe that all wire sounds the same
> provided it is of the "correct type". What I'm trying to find out here
> is what the correct type is. I am not so interested in general claims
> that cannot be used in practice to make decisions.
>
> Thanks for the input.
>
>
> /August

All wire sounds exactly the same. Copper zip cord, 14 Gauge or bigger should
be sufficient for any 4-meter run for any domestic amplifier or speaker
setup. If you have a really big amp (say 700 watts/channel or more), you
might want to increase that size to something like the bulk cable used in
industrial-sized extension cords (12 -10 Gauge). Forget everything else, it
doesn't matter.

"August Karlstrom" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On 2010-10-17 03:17, Trevor Wilson wrote:
>> "August Karlstrom"<(E-Mail Removed)> wrote in message
>>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>>
>> **Like all such cliams, the Wiki article over-simplifies things. They
>> ignore
>> the very real effects of inductance, when using long cable runs and
>> speakers
>> which exhibit a falling impedance at HF (like ESLs). In those cases, the
>> inductive effects of cable can become quite significant.
>
> To take my example again, let's say I need a pair of cables, each four
> meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
> wire would be insufficient?

**Without knowing the impedance curve (20Hz ~ 20kHz) of your speakers, I
cannot say. In all probability, yes, it would be OK.

>
> Several people in this newsgroup believe that all wire sounds the same
> provided it is of the "correct type". What I'm trying to find out here is
> what the correct type is. I am not so interested in general claims that
> cannot be used in practice to make decisions.

**There are three characteristics of speaker cable that are of interest.
They are:

* Resistance. The lower the better.
* Inductance. The lower the better.
* Capacitance. Largely unimportant, when using a competently designed
amplifier.

That leaves resistance (R) and inductance (L). The significance of the two
paramaters depends on the impedance of the speaker and the length of the
cable. 4 Metres is a modest cable run and SHOULD present few problems in any
system.

Resistance is governed by the amount of conductive material in the cable.
Indutance is much more complicated. Standard 'zip' type speaker cables
(basically any parallel pair of conductors) exhibits pretty much the highest
possible inductance. The wider the spacing of the cable conductors (see:
Naim speaker cable), the higher the inductance and less desirable the cable.
As the conductor spacing is made smaller, the inductance falls. Some
manufacturers use multiple conductors, closely bound together to reduce
inductance still further. Others (Goertz, et al) use flat conductors, in
intimate proximity to reduce inductance to extremely low levels. For my
part, I suggest the use of RG213/U coax cable, which exhibits quite low
resistance and very low inductance, at reasonable cost.


--
Trevor Wilson
www.rageaudio.com.au

On Sun, 17 Oct 2010 16:08:37 -0700, Trevor Wilson wrote
(in article <(E-Mail Removed)>):

> "August Karlstrom" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> On 2010-10-17 03:17, Trevor Wilson wrote:
>>> "August Karlstrom"<(E-Mail Removed)> wrote in message
>>>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>>>
>>> **Like all such cliams, the Wiki article over-simplifies things. They
>>> ignore
>>> the very real effects of inductance, when using long cable runs and
>>> speakers
>>> which exhibit a falling impedance at HF (like ESLs). In those cases, the
>>> inductive effects of cable can become quite significant.
>>
>> To take my example again, let's say I need a pair of cables, each four
>> meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
>> wire would be insufficient?
>
> **Without knowing the impedance curve (20Hz ~ 20kHz) of your speakers, I
> cannot say. In all probability, yes, it would be OK.
>
>>
>> Several people in this newsgroup believe that all wire sounds the same
>> provided it is of the "correct type". What I'm trying to find out here is
>> what the correct type is. I am not so interested in general claims that
>> cannot be used in practice to make decisions.
>
> **There are three characteristics of speaker cable that are of interest.
> They are:
>
> * Resistance. The lower the better.
> * Inductance. The lower the better.
> * Capacitance. Largely unimportant, when using a competently designed
> amplifier.

I practice, none of these things have the slightest effect on the sound.
Resistence/foot is less than a 0.006 Ohm for 14 Ga. zip.

> That leaves resistance (R) and inductance (L). The significance of the two
> paramaters depends on the impedance of the speaker and the length of the
> cable. 4 Metres is a modest cable run and SHOULD present few problems in any
> system.

Capacitance is around 12pf/foot or about 144pf for 4 meters of 14 Ga zip
cord. It has been found that capacitive loads of up to 20,000 pf (.02 mfd)
have no audible or visible effect on audio signals. That means that 4 meters
of 14 Ga zip cord would need 100 times more capacitance/foot to have any
effect whatsoever on a an audio signal passing through it. Inductance is
likewise negligible.

One can run 80 ft of 14 Ga zip as speaker cable for 8 Ohm speakers before it
is recommended that one increase the wire size to 12 Ga.

IOW, as long as the zip cord is 14 Ga or larger and your runs are less than
80ft, don't sweat it. just buy what you like and cheap hardware store zip
cord is FINE.

In article <(E-Mail Removed)>,
Audio Empire <(E-Mail Removed)> wrote:

> On Sun, 17 Oct 2010 06:54:25 -0700, August Karlstrom wrote
> (in article <(E-Mail Removed)>):
>
> > On 2010-10-17 03:17, Trevor Wilson wrote:
> >> "August Karlstrom"<(E-Mail Removed)> wrote in message
> >>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
> >>
> >> **Like all such cliams, the Wiki article over-simplifies things. They
> >> ignore
> >> the very real effects of inductance, when using long cable runs and
> >> speakers
> >> which exhibit a falling impedance at HF (like ESLs). In those cases, the
> >> inductive effects of cable can become quite significant.
> >
> > To take my example again, let's say I need a pair of cables, each four
> > meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
> > wire would be insufficient?
> >
> > Several people in this newsgroup believe that all wire sounds the same
> > provided it is of the "correct type". What I'm trying to find out here
> > is what the correct type is. I am not so interested in general claims
> > that cannot be used in practice to make decisions.
> >
> > Thanks for the input.
> >
> >
> > /August
>
> All wire sounds exactly the same. Copper zip cord, 14 Gauge or bigger should
> be sufficient for any 4-meter run for any domestic amplifier or speaker
> setup. If you have a really big amp (say 700 watts/channel or more), you
> might want to increase that size to something like the bulk cable used in
> industrial-sized extension cords (12 -10 Gauge). Forget everything else, it
> doesn't matter.

Why is the wire size used to feed the speakers so much more important
than the wire used *in* the speaker -- for crossovers and more
importantly, for the voice coil? Clearly, the *length* of the latter two
far exceeds the former.

Isaac

Trevor Wilson wrote:
> "August Karlstrom" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> On 2010-10-17 03:17, Trevor Wilson wrote:
>>> "August Karlstrom"<(E-Mail Removed)> wrote in message
>>>> http://en.wikipedia.org/wiki/Speaker_wire#Wire_gauge
>>> **Like all such cliams, the Wiki article over-simplifies things. They
>>> ignore
>>> the very real effects of inductance, when using long cable runs and
>>> speakers
>>> which exhibit a falling impedance at HF (like ESLs). In those cases, the
>>> inductive effects of cable can become quite significant.
>> To take my example again, let's say I need a pair of cables, each four
>> meters long. Is there a system in which a 2x1.5 mm2 (approx.15 AWG) OFC
>> wire would be insufficient?
>
> **Without knowing the impedance curve (20Hz ~ 20kHz) of your speakers, I
> cannot say. In all probability, yes, it would be OK.

4m of zip cable will do on any home-use speakres, Kappa 9 included.

>
>> Several people in this newsgroup believe that all wire sounds the same
>> provided it is of the "correct type". What I'm trying to find out here is
>> what the correct type is. I am not so interested in general claims that
>> cannot be used in practice to make decisions.
>
> **There are three characteristics of speaker cable that are of interest.
> They are:
>
> * Resistance. The lower the better.
> * Inductance. The lower the better.

At 4m cable length inductance is unimportant.

> * Capacitance. Largely unimportant, when using a competently designed
> amplifier.
>
> That leaves resistance (R) and inductance (L). The significance of the two
> paramaters depends on the impedance of the speaker and the length of the
> cable. 4 Metres is a modest cable run and SHOULD present few problems in any
> system.

I would say no problems in any home system.

> Resistance is governed by the amount of conductive material in the cable.
> Indutance is much more complicated. Standard 'zip' type speaker cables
> (basically any parallel pair of conductors) exhibits pretty much the highest
> possible inductance. The wider the spacing of the cable conductors (see:
> Naim speaker cable), the higher the inductance and less desirable the cable.
> As the conductor spacing is made smaller, the inductance falls. Some
> manufacturers use multiple conductors, closely bound together to reduce
> inductance still further. Others (Goertz, et al) use flat conductors, in
> intimate proximity to reduce inductance to extremely low levels. For my
> part, I suggest the use of RG213/U coax cable, which exhibits quite low
> resistance and very low inductance, at reasonable cost.

It's an overkill unless you use >20m cable together with extremely low
(broken by design?) impedance (<1.5ohm) speakers.


rgds
\SK
--
"Never underestimate the power of human stupidity" -- L. Lang
--
http://www.tajga.org -- (some photos from my travels)