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  #1   Report Post  
 
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Default speaker wire vs. lamp cord

for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ
  #2   Report Post  
Arny Krueger
 
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wrote in message

for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??


Plan "B" 12 gauge low voltage stranded wire from your local builder's supply
or hardware store. Both Home Depot and Lowe's stock it, for example.


  #3   Report Post  
 
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Not the same as regular lamp cord???

"Arny Krueger" wrote:

wrote in message

for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??


Plan "B" 12 gauge low voltage stranded wire from your local builder's supply
or hardware store. Both Home Depot and Lowe's stock it, for example.




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  #4   Report Post  
Kevin McMurtrie
 
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In article ,
wrote:

for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ


There are only two basic requirements:
- The wire's resistance should be very low compared to the speaker's
impedance.
- The two wires must be as close as possible to each other to reduce
inductance.

You can check the tables here or Google for other resistance charts.
http://documents.epanorama.net/docum...esistance.html


How good the wire needs to be depends on the quality of the speaker.
Wire resistance reduces dampening of the speaker's own resonations, it's
coloring. It's OK to skimp on speakers used for surround effects
because they're usually running off a Lo-Fi signal anyways. 1 Ohm loss
would be usable for 8 Ohm surrounds. The primary speakers would
probably sound best with less than .5 Ohms loss.

Solid-core twisted-pair in-wall wire works great too. It's just tough
to manage it without securing it every few feet.
  #5   Report Post  
Stu-R
 
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"Expensive" speaker wire - 12 ga. can be had on the web for as low as
$36/100ft. Definitely for less than $50/100ft. An alternative is to
parallel one or two pairs of 14 ga. lamp cord to get the same
resistance/ft. Easiest way to check is to take one 14 ga. lamp cord
and tie the pair at one end together. Do the same with the other end,
use it as a single wire. Do the same for the other speaker lead. See
if they sound better. You can even tie two lamp cord sections in
parallel ( 4 conductors) for each speaker lead and get it down to
equal about 10 ga. I did this once and there was an audible
improvement. I assume that your Hsu is not a powered unit.


On Sat, 18 Sep 2004 19:56:35 -0400, wrote:

for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ




  #6   Report Post  
Arny Krueger
 
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wrote in message


Not the same as regular lamp cord???


Heavier gauge.

"Arny Krueger" wrote:

wrote in message

for my new Hsu surround sound system, I have to run so long wires.
is 14 gauge lamp cord ok ($25/250 feet) or must it be expensive
"speaker wire"??


Plan "B" 12 gauge low voltage stranded wire from your local
builder's supply or hardware store. Both Home Depot and Lowe's stock
it, for example.




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News==---- http://www.newsfeed.com The #1 Newsgroup Service in the
World! 100,000 Newsgroups
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  #7   Report Post  
Arny Krueger
 
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"Kevin McMurtrie" wrote in message


In article ,
wrote:


for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ


There are only two basic requirements:
- The wire's resistance should be very low compared to the speaker's
impedance.
- The two wires must be as close as possible to each other to reduce
inductance.


You can check the tables here or Google for other resistance charts.
http://documents.epanorama.net/docum...esistance.html

So far so good.


How good the wire needs to be depends on the quality of the speaker.


Kevin, what is the criteria for speaker wire goodness? Did you say?

Wire resistance reduces dampening of the speaker's own resonations,
it's coloring.


This seems to be said in an inverted way.

A wire with low resistance does a better job of accurately delivering the
voltage at the output of the amplifier to the speaker terminals. Conversely
a wire with high resistance does a poorer job of accurately delivering the
voltage at the output of the amplifier to the speaker terminals. IOW, the
high resistance wire will add additional voltage variations, that depend on
the speaker's own resonance's, among other things.

It's OK to skimp on speakers used for surround effects
because they're usually running off a Lo-Fi signal anyways. 1 Ohm
loss would be usable for 8 Ohm surrounds. The primary speakers would
probably sound best with less than .5 Ohms loss.


For best results, the loss in the speaker cables should be less than 1-3% of
the minimum impedance of the speaker. There's a procedure for sizing speaker
wires posted at http://www.pcavtech.com/techtalk/wire_size/index.htm

Solid-core twisted-pair in-wall wire works great too. It's just tough
to manage it without securing it every few feet.


Agreed.


  #8   Report Post  
Trevor Wilson
 
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wrote in message
...
for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??


**You don't mention the length of the cable, nor the impedance
characteristics of your speaker, so it is impossible for anyone to answer
your question.

BTW: Good speaker cable (IE: Low resistance/low inductance type) need not be
expensive.


--
Trevor Wilson
www.rageaudio.com.au


  #10   Report Post  
Kevin McMurtrie
 
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In article ,
"Arny Krueger" wrote:

"Kevin McMurtrie" wrote in message


In article ,
wrote:


for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ


There are only two basic requirements:
- The wire's resistance should be very low compared to the speaker's
impedance.
- The two wires must be as close as possible to each other to reduce
inductance.


You can check the tables here or Google for other resistance charts.
http://documents.epanorama.net/docum...esistance.html

So far so good.


How good the wire needs to be depends on the quality of the speaker.


Kevin, what is the criteria for speaker wire goodness? Did you say?

Wire resistance reduces dampening of the speaker's own resonations,
it's coloring.


This seems to be said in an inverted way.

A wire with low resistance does a better job of accurately delivering the
voltage at the output of the amplifier to the speaker terminals. Conversely
a wire with high resistance does a poorer job of accurately delivering the
voltage at the output of the amplifier to the speaker terminals. IOW, the
high resistance wire will add additional voltage variations, that depend on
the speaker's own resonance's, among other things.


No, I meant same thing. Wire resistance lets the speaker do more of
what it wants to do electrically and mechanically. You can put a beefy
10 Ohm resistor in series with your speakers to hear an exaggeration of
what happens. Generally you loose some bass and get an uneven midrange
response.


It's OK to skimp on speakers used for surround effects
because they're usually running off a Lo-Fi signal anyways. 1 Ohm
loss would be usable for 8 Ohm surrounds. The primary speakers would
probably sound best with less than .5 Ohms loss.


For best results, the loss in the speaker cables should be less than 1-3% of
the minimum impedance of the speaker. There's a procedure for sizing speaker
wires posted at http://www.pcavtech.com/techtalk/wire_size/index.htm

Solid-core twisted-pair in-wall wire works great too. It's just tough
to manage it without securing it every few feet.


Agreed.



  #11   Report Post  
Jerry G.
 
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Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length. For short distances,
you will not hear the difference, between speaker wire, and a heavy duty
lamp cord.

If you have a descent DVM, you an measure the DC resistance of a pair of
wires to start with. Take a 100 ft length, and short the pairs at the
far end. At the close end measure its resistance. Do the same for each
type.

To test for the return loss due to its capacitive reactance, and
inductive reactance, you will need a sophisticated setup, using a
laboratory reference amplifier, audio sweep generator, 8 ohm 100 W dummy
load, and a scope. Connect the 100 foot length of wire to be tested on
to the amplifier with the 8 ohm dummy load connected to the far end.
Connect the audio sweep generator to the amplifier, and set the sweep
output for 20 to 20K at line sync rate. Connect the scope to the other
end, and set its scale to be for 1 V-cm AC coupled. Set the scope sync
line rate for line sync. Set the scope time base for 50 ms/cm to start
with. Turn the system on, and calibrate at 400 Hz to have the scope to
full scale P-P. Turn on the sweep mode and observe the flatness of the
sweep. You can trim the veneer or timebase on the scope for the best
resolving. If you use the delayed sweep option on the scope you will be
able to see any segments of the response, and expand on them.

After performing the above, you can then compare the different wires to
see the effects. You would be surprised to see how the different types
of wires perform. If you do the math, you can calculate the Db drops. If
you want to get sophisticated using a dual sweep scope, you can get in
to working out the phase delay errors and etc. With a distortion
analyser, you can also start getting in to the harmonics that the
different wires will produce in relation to each other. All of this
becomes part of the sound quality.

Personally, I would use speaker cord. The cost difference is not
something that is going to break the bank, for the possible gain.

--

Jerry G.
======

wrote in message
...
for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??
Thanks
DoctorJ


  #12   Report Post  
Dick Pierce
 
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"Jerry G." wrote in message ...
Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length.


This is pure, utter nonsense. The resistance of the wire is determined
NOT by the stranding, but by the net wire gauge and the bulk material.
Very fine stranded 12 gauge copper wire has the same resistance as coarse
stranded 12 gauge copper wire. The primary advnatge afforded by going
to the fine stranded version is in mechanical flexibility.

It does NOT change the resistance at all.
  #13   Report Post  
Dick Pierce
 
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Kevin McMurtrie wrote in message ...
How good the wire needs to be depends on the quality of the speaker.
Wire resistance reduces dampening of the speaker's own resonations, it's
coloring.


Uh, that would be "resonances" and no, unless you are using VERY tiny
wire, the resistance of the speaker wire does NOT reduce damping of
the only relevant resonance in the speaker, the fundamental mechanical
resonance. A couple of important points behind this:

1. By far, the largest source of series resistance that affects
the damping of the speaker resonance is NOT the speaker wire,
but the very DC resistance of the voice coil in the driver
itself. Unless that resistance is reduced A LOT (it's typically
on the order of 80% or more of the nominal impedance of the
speaker) OR you're using something like 28 gauge wire, the
voice coil DC resistance will completely dominate the total
series loop resistance and render pretty irrelevant differences
in nomimally competently designed and selected speaker cable.
Consider, for instance, the difference between a 10 foot run of
16 gauge vs 12 gauge speaker wire. The former will have a total
series resistance of 0.08 ohms vs 0.03 ohms. Now, one might
that the 12 gauge has about 2.5 times better damping than the
16 gauge, and that would be wrong. If the speaker voice coil has
a DC resistance of 6.5 ohms, say, it's the difference then between
6.58 and 6.53 ohms, and now the difference in damping is more
on the order of under 1%, hardly relevant.

2. In any case, the effects on damping caused by the speaker wire
cannot affect resonances that have no manifestation in the
electrical impedance. That means that, for the most part, the
ONLY resonance affected is that of the fundamental mechanical
resonance of the driver/system. The vast majority of resonance
of the sort caused by diaphragm breakup and such are simply
untouched by changing the cable, even in the worst scenarios.
  #15   Report Post  
Pooh Bear
 
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"Jerry G." wrote:

Speaker wire is of a finer stran, thus having less resistance.


No it doesn't.

For a given length os wire, the resitance is purely determined by the
cross-sectional area. Stranding makes no difference whatever.

It is designed to have less reactance over its length.


Wrong again !

The inductance is determined by the 'loop area' which again has nothing
whatever to do with stranding. Nor will cable capacitance be affected by
stranding.

The only effect of significance regarding stranding is skin-effect but at
audio frequencies about 2mm dia strands can be used without skin effect
being an issue IIRC.


Graham



  #17   Report Post  
Geoff Wood
 
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"Jerry G." wrote in message
...

Speaker wire is of a finer stran, thus having less resistance.


Could you explain the physics of how this works ?

geoff


  #18   Report Post  
Trevor Wilson
 
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"Jerry G." wrote in message
...
Speaker wire is of a finer stran, thus having less resistance.


**Nonsense.

It is
designed to have less reactance over its length.


**Not necessarily. Naim cable, for instance, is specifically designed for
high inductance.

For short distances,
you will not hear the difference, between speaker wire, and a heavy duty
lamp cord.


**It depends on the load and the actual length of the cable.



If you have a descent DVM, you an measure the DC resistance of a pair of
wires to start with. Take a 100 ft length, and short the pairs at the
far end. At the close end measure its resistance. Do the same for each
type.

To test for the return loss due to its capacitive reactance, and
inductive reactance, you will need a sophisticated setup, using a
laboratory reference amplifier, audio sweep generator, 8 ohm 100 W dummy
load, and a scope. Connect the 100 foot length of wire to be tested on
to the amplifier with the 8 ohm dummy load connected to the far end.
Connect the audio sweep generator to the amplifier, and set the sweep
output for 20 to 20K at line sync rate. Connect the scope to the other
end, and set its scale to be for 1 V-cm AC coupled. Set the scope sync
line rate for line sync. Set the scope time base for 50 ms/cm to start
with. Turn the system on, and calibrate at 400 Hz to have the scope to
full scale P-P. Turn on the sweep mode and observe the flatness of the
sweep. You can trim the veneer or timebase on the scope for the best
resolving. If you use the delayed sweep option on the scope you will be
able to see any segments of the response, and expand on them.


**YIKES! You like to do things the hard way. It is MUCH easier to do that
that. A millivoltmeter (or a CRO) and an oscillator is all you need. Compare
the Voltage at 50Hz and 20kHz. Then it is a trivial exercise to determine
the reactance of the cable. BTW: Capacitive reactance is is no interest.


--
Trevor Wilson
www.rageaudio.com.au


  #19   Report Post  
Laurence Payne
 
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On Mon, 20 Sep 2004 04:28:14 -0400, "Jerry G."
wrote:

Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length. For short distances,
you will not hear the difference, between speaker wire, and a heavy duty
lamp cord.


er......******** :-)
  #21   Report Post  
Stewart Pinkerton
 
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On Tue, 21 Sep 2004 00:23:59 +0100, Laurence Payne
wrote:

On Mon, 20 Sep 2004 04:28:14 -0400, "Jerry G."
wrote:

Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length. For short distances,
you will not hear the difference, between speaker wire, and a heavy duty
lamp cord.


er......******** :-)


What, you mean you *will* hear the difference? :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #22   Report Post  
Clifford Heath
 
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Dick Pierce wrote:
"Jerry G." wrote in message ...
Speaker wire is of a finer stran, thus having less resistance.

This is pure, utter nonsense.


Maybe he meant resistance to bending :-)))
  #23   Report Post  
TonyP
 
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Dick Pierce wrote:

Well, actually, no. If it's spec'ed at 12 gauge, the spec comes from the
effective conductor cross-sectional area, so that's taken into account.

Be that as it may, the difference in resistance if this weren't the
case is still MUCH smaller than the total series resistance, dominated
as it is, actually overwhe4lmed by the voice coil DC resistance.


I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood what
happened and why. And, if you used those speaker cables today, would the
results be the same.
Thanks.

  #24   Report Post  
John Krieger
 
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Not actually nonesense, since the current runs mostly in the surface of the
iwr. Finer strands = more surface are = less resistance.



"Dick Pierce" wrote in message
om...
"Jerry G." wrote in message

...
Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length.


This is pure, utter nonsense. The resistance of the wire is determined
NOT by the stranding, but by the net wire gauge and the bulk material.
Very fine stranded 12 gauge copper wire has the same resistance as coarse
stranded 12 gauge copper wire. The primary advnatge afforded by going
to the fine stranded version is in mechanical flexibility.

It does NOT change the resistance at all.



  #25   Report Post  
Arny Krueger
 
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"John Krieger" wrote in message


Not actually nonsense, since the current runs mostly in the surface
of the wire. Finer strands = more surface are = less resistance.


Wrong on several grounds.

(1) The depth of the conductive layer @ 20 KHz and below is a very
significant portion of the thickness of even 12 gauge wire.

(2) Secondly, skin effect is based on magnetism. The magnetic lines of force
pass among the strands of wire in a cable quite freely. So, merely stranding
and bundling or twisting the strands has little effect. Even insulating the
individual strands has little effect.

If you want to make a cable that has reduced skin effect @20 KHz and below,
you have to make a conductor that is hollow and fairly large like a piece of
tubing. If stranded wire is used for this to maintain flexibility, it is
wound around a fairly large core composed of non-conductive and non-magnetic
material.




  #26   Report Post  
Pooh Bear
 
Posts: n/a
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John Krieger wrote:

Not actually nonesense, since the current runs mostly in the surface of the
iwr. Finer strands = more surface are = less resistance.


This is an A.C. effect that's only relevant at high frequencies.

For example, I have just been designing a switch mode power supply operating at
130kHz. The maximum conductor diameter recommended to avoid skin effect at this
frequency is 0.4mm.

Scale this to audio frequencies and you'll see the nonsence of the finely
stranded argument.

Low cable impedance is most relevant at LF anyway (damping factor for LF driver
).

Furthermore, an internal passive crossover ( as is most usually the case )
presents a much higher impedance to the LF and HF drivers than the amplifier or
cable combined !


Graham

  #28   Report Post  
Stewart Pinkerton
 
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On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:

I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood what
happened and why. And, if you used those speaker cables today, would the
results be the same.


Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #29   Report Post  
Geoff Wood
 
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"John Krieger" wrote in message
...
Not actually nonesense, since the current runs mostly in the surface of
the
iwr. Finer strands = more surface are = less resistance.


Yep, at 200KHz or so. But these strands are touching, so do not act as
individual conductors.


geoff


  #30   Report Post  
Dick Pierce
 
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"John Krieger" wrote in message ...
"Dick Pierce" wrote in message
om...
"Jerry G." wrote in message

...
Speaker wire is of a finer stran, thus having less resistance. It is
designed to have less reactance over its length.


This is pure, utter nonsense. The resistance of the wire is determined
NOT by the stranding, but by the net wire gauge and the bulk material.
Very fine stranded 12 gauge copper wire has the same resistance as coarse
stranded 12 gauge copper wire. The primary advnatge afforded by going
to the fine stranded version is in mechanical flexibility.

It does NOT change the resistance at all.


Not actually nonesense, since the current runs mostly in the
surface of the iwr. Finer strands = more surface are = less
resistance.


You're speaking of the "skin effect" and you're wrong on at least
two counts. First, the current does NOT run "mostly on the surface"
at audio frequencies. Over the vast majority of the bandwidth, the
skin effect is negligable. Second, at those significantly higher
frequencies where it is appreciable, the stranding of the sort
found in speaker canles has no effect, as the current will confine
itself to the surface of the entire bundle, making a stranded cable
act essentially as a single solid conductor for all intents and
purposes.


  #31   Report Post  
TonyP
 
Posts: n/a
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Stewart Pinkerton wrote:

On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:


I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood what
happened and why. And, if you used those speaker cables today, would the
results be the same.


Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.


Thanks for the reply. What was the "advantage" of high capacitive cables?

  #32   Report Post  
Stewart Pinkerton
 
Posts: n/a
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On Thu, 23 Sep 2004 01:01:44 GMT, TonyP
wrote:

Stewart Pinkerton wrote:

On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:


I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood what
happened and why. And, if you used those speaker cables today, would the
results be the same.


Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.


Thanks for the reply. What was the "advantage" of high capacitive cables?


In general, a cable which exhibits high capacitance will also exhibit
low inductance. Low inductance is *theoretically* desirable in a
speaker cable, as it reduces the cable reactance at high frequencies.
In practice, even driving a 3-ohm load over thirty feet of cable with
Naim NACA5 (probably the *highest* inductance cable commonly
available) will result in a treble droop of less than 1dB at 20kHz.

Some of those low-inductance cables, such as Alpha Core 'Goertz' MI
claim to have a 'matched' impedance, as the characteristic impedance
of the cable is only 6-8 ohms, as opposed to the 50-100 ohms of most
speaker cable. In reality, this is an insupportable argument, since
the cable is not being driven from a 6-8 ohm source, speaker impedance
varies wildly, and a matched impedance would in any case only be of
importance when cable length exceeds about 1/10 of a wavelength. The
wavelength of a 20kHz signal in such a cable is about six *miles*....
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #35   Report Post  
TonyP
 
Posts: n/a
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Stewart Pinkerton wrote:

On Thu, 23 Sep 2004 01:01:44 GMT, TonyP
wrote:


Stewart Pinkerton wrote:


On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:


Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.


Thanks for the reply. What was the "advantage" of high capacitive cables?


In general, a cable which exhibits high capacitance will also exhibit
low inductance. Low inductance is *theoretically* desirable in a
speaker cable, as it reduces the cable reactance at high frequencies.
In practice, even driving a 3-ohm load over thirty feet of cable with
Naim NACA5 (probably the *highest* inductance cable commonly
available) will result in a treble droop of less than 1dB at 20kHz.

Some of those low-inductance cables, such as Alpha Core 'Goertz' MI
claim to have a 'matched' impedance, as the characteristic impedance
of the cable is only 6-8 ohms, as opposed to the 50-100 ohms of most
speaker cable. In reality, this is an insupportable argument, since
the cable is not being driven from a 6-8 ohm source, speaker impedance
varies wildly, and a matched impedance would in any case only be of
importance when cable length exceeds about 1/10 of a wavelength. The
wavelength of a 20kHz signal in such a cable is about six *miles*....


Thanks again for the reply. I gather then, that, this type of speaker
wire offers no real advantage in normal applications, and would not be
really cost effective.



  #36   Report Post  
CJT
 
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Ron Capik wrote:
Alex Rodriguez wrote:


In article ,
says...


for my new Hsu surround sound system, I have to run so long wires. is
14 gauge lamp cord ok ($25/250 feet) or must it be expensive "speaker
wire"??


If really long runs, get 12 gauge. With the money you save you can buy
some more music to play through your system.
------------
Alex



Also note that lamp (zip) cord has a flat edge and a round edge that you can
use to maintain (or keep track of) polarity.

Ron Capik
NJ Pinelands Cultural Society
www.AlbertHall.org
--

I've never seen ANY kind of paired wire that didn't have SOME kind of
way to distinguish the wires -- color, printing, texture on the
insulation, a wrap or thread, etc.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .
  #37   Report Post  
Stewart Pinkerton
 
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On Thu, 23 Sep 2004 23:18:27 GMT, TonyP
wrote:

Stewart Pinkerton wrote:

On Thu, 23 Sep 2004 01:01:44 GMT, TonyP
wrote:


Thanks for the reply. What was the "advantage" of high capacitive cables?


In general, a cable which exhibits high capacitance will also exhibit
low inductance. Low inductance is *theoretically* desirable in a
speaker cable, as it reduces the cable reactance at high frequencies.
In practice, even driving a 3-ohm load over thirty feet of cable with
Naim NACA5 (probably the *highest* inductance cable commonly
available) will result in a treble droop of less than 1dB at 20kHz.

Some of those low-inductance cables, such as Alpha Core 'Goertz' MI
claim to have a 'matched' impedance, as the characteristic impedance
of the cable is only 6-8 ohms, as opposed to the 50-100 ohms of most
speaker cable. In reality, this is an insupportable argument, since
the cable is not being driven from a 6-8 ohm source, speaker impedance
varies wildly, and a matched impedance would in any case only be of
importance when cable length exceeds about 1/10 of a wavelength. The
wavelength of a 20kHz signal in such a cable is about six *miles*....


Thanks again for the reply. I gather then, that, this type of speaker
wire offers no real advantage in normal applications, and would not be
really cost effective.


In so far as it will sound identical to 12AWG zipcord, that would be
correct.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
  #38   Report Post  
Trevor Wilson
 
Posts: n/a
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"Stewart Pinkerton" wrote in message
...
On Thu, 23 Sep 2004 01:01:44 GMT, TonyP
wrote:

Stewart Pinkerton wrote:

On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:


I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood

what
happened and why. And, if you used those speaker cables today, would

the
results be the same.


Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.


Thanks for the reply. What was the "advantage" of high capacitive cables?


In general, a cable which exhibits high capacitance will also exhibit
low inductance. Low inductance is *theoretically* desirable in a
speaker cable, as it reduces the cable reactance at high frequencies.
In practice, even driving a 3-ohm load over thirty feet of cable with
Naim NACA5 (probably the *highest* inductance cable commonly
available) will result in a treble droop of less than 1dB at 20kHz.


**Except that, with some speakers (notably electrostatics), low inductance
cables may well be desirable. Here is the impedance curve of just such a
speaker:

www.rageaudio.com.au/accu.jpg

In this situation, NAIM cables (unless the speaker is to used with a NAIM
amplifier) would be the very worst choice imaginable. Standard Figure 8 (Zip
cable) would be a slightly less worse choice. High power coax, or Goertz
MI-1 would be the best choices.


--
Trevor Wilson
www.rageaudio.com.au


  #39   Report Post  
Isaac Wingfield
 
Posts: n/a
Default

In article ,
"Trevor Wilson" wrote:

"Stewart Pinkerton" wrote in message
...
On Thu, 23 Sep 2004 01:01:44 GMT, TonyP
wrote:

Stewart Pinkerton wrote:

On Tue, 21 Sep 2004 22:32:42 GMT, TonyP
wrote:

I remember reading about speaker cables that caused some amps major
grief. I believe it was the Polk speaker cables. I never understood

what
happened and why. And, if you used those speaker cables today, would

the
results be the same.

Highly capacitive cables triggered HF oscillation in amplifiers which
were only marginally stable, most notably the Naim NAP250. Avoid Naim
amps, and no modern amplfier should have a problem in this regard.
OTOH, you don't need such weird cables anyway, except in the most
extreme case of say an electrostat speaker driven by more than 30 feet
of cable.

Thanks for the reply. What was the "advantage" of high capacitive cables?


In general, a cable which exhibits high capacitance will also exhibit
low inductance. Low inductance is *theoretically* desirable in a
speaker cable, as it reduces the cable reactance at high frequencies.
In practice, even driving a 3-ohm load over thirty feet of cable with
Naim NACA5 (probably the *highest* inductance cable commonly
available) will result in a treble droop of less than 1dB at 20kHz.


**Except that, with some speakers (notably electrostatics), low inductance
cables may well be desirable. Here is the impedance curve of just such a
speaker:

www.rageaudio.com.au/accu.jpg

In this situation, NAIM cables (unless the speaker is to used with a NAIM
amplifier) would be the very worst choice imaginable. Standard Figure 8 (Zip
cable) would be a slightly less worse choice. High power coax, or Goertz
MI-1 would be the best choices.


If you actually do the calculations to determine the "characteristic
impedance" of a transmission line in the audio frequency range, you
might be more than a little surprised. The line doesn't have one; it is
frequency dependent, unlike the situation at "RF".

See the "Schaum's Outline Series" tutorial on Transmission Lines to
learn how to do the calculations correctly. Most "transmission line"
texts do not cover how "characteristic impedance" is calculated at low
frequencies; that one does .The calculation is nowhere near the same as
at higher frequencies.

Isaac
  #40   Report Post  
Pooh Bear
 
Posts: n/a
Default

Isaac Wingfield wrote:

If you actually do the calculations to determine the "characteristic
impedance" of a transmission line in the audio frequency range, you
might be more than a little surprised. The line doesn't have one; it is
frequency dependent, unlike the situation at "RF".


That's because audio frequencies have very long wavelengths.

Only when the cable length approaches the signal wavelength does a characteristic
impedance become a relevant issue.


Graham

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