Audio Empire wrote:
On Sun, 17 Oct 2010 16:08:37 -0700, Trevor Wilson wrote
(in article ):
"August Karlstrom" wrote in message
...
On 2010-10-17 03:17, Trevor Wilson wrote:
"August 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 a
* 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.
**Incorrect. Both resistance and inductance can affect sound quality,
depending on the length of the cable and the impedance of the speaker.
Capacitance, as I have already stated many times, is irrelevant with any
properly 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.
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.
**As I carefully pointed out, capacitance is irrelevant.
Inductance is likewise negligible.
**No. Inductance is not negligible. It *may* be irrelevant, depending on the
length of the cable and the speakers used, however.
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.
**Just a reminder: There is no such thing as an "8 Ohm speaker". All
speakers, with the possible exception of Maggies, exhibit varying
impedances. SOME speakers, like ESLs, which may present a relatively high
impedance over most of the audible range, can often present very low
impedances at high frequencies. Here is one such example:
http://www.rageaudio.com.au/index.php?p=1_12
Click on 'Accustat'.
With a 25 Metre length of standard 'zip' type speaker cable, a serious and
very audible problem at HF can be expected. Low resistance and low
inductance cables are absolutely essential with such speakers and such long
cable runs.
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.
**I have no issue with cheap, but misleading people by suggesting that they
can connect very long cables to speakers and expecting no problems is just
wrong.
--
Trevor Wilson
www.rageaudio.com.au