orson whitfield

Long run of speaker cable: to shield or not to shield
« on: December 26, 2004, 03:30:36 PM »
I'm thinking I need around 110' of speaker cable for each channel.  Do I go shielded for this length?  And what guage do you recomend?  Sorry if this is a no brainer but budget matters.  Also,  any favorite brand?

THanks In Advance


rlaury

Long run of speaker cable: to shield or not to shield
« Reply #1 on: December 26, 2004, 03:48:27 PM »
Is it possible to move the power amps closer to the load and rune line level shielded cable to the amps? If this is for a high quality system, that's the best option. If not, use the heaviest cable you can get your hands on and don't shield it. At 4 or 8 ohms the radiation resistance is so low anyway that it shouldn?t be a problem. Use four wire 8-10ga. appliance cable thats used on ovens or dryers. Parallel inner conductors to obtain a single pair for each channel.

Good Luck
RonL
When all you have to work with is a hammer,
everything looks like a nail.

Kev

Long run of speaker cable: to shield or not to shield
« Reply #2 on: December 26, 2004, 04:15:29 PM »
Quote from: "rlaury"
... Use four wire 8-10ga. appliance cable thats used on ovens or dryers. Parallel inner conductors to obtain a single pair for each channel.


Now I'd prefer to use  more strands.
A 10 amp 3 core extension lead and use all three conductors.
This gives the crossectional area and multi strands of good quality copper.

Perhaps even variants and combinations of the above.  It will still be a long way cheaper than Audiophool cable and I'm absolutely sure it will work as well ... perhaps even better.
Kev
DIY Factory

PRR

Long run of speaker cable: to shield or not to shield
« Reply #3 on: December 27, 2004, 01:04:08 AM »
> Do I go shielded for this length?

Never shield speaker wires!!!

You certainly are NOT going to pick up interference: stray fields are microwatts and speakers need watts to make noise.

More important: many speaker amps can get unhappy with excess capacitance. Most will handle 1uFd semi-gracefully, which is 6 miles, so not a problem; but there are a few that will not like even 1,000pFd which is about 30 feet.

If you just want "good" sound, use 14 gauge. Heck, I've used far longer runs of 16 gauge and nobody noticed. For really great sound on speakers that would normally be in the same room with the amp, use fatter copper.

For permanent installation, NMC home-wire cable is your best deal. And I'm not sold on any benefits of stranding (aside from flexing). Even so, 250 feet of #10-2(G) or #8-2(G) is not cheap.

Re: Long run of speaker cable: to shield or not to shield
« Reply #4 on: December 27, 2004, 08:40:00 AM »
Quote from: "orson whitfield"
Do I go shielded for this length?  And what guage do you recomend?  Sorry if this is a no brainer but budget matters.  Also,  any favorite brand?
THanks In Advance

There is not problem in microwatts of disturbing RF field.
Some power amps have output network, which shield it
(and no detection at output stage can occurs).
It is simple series choke between Boucherot R+C and output plugs.
Only problem with repro cables are resistance.
Use normal power cables, Better is, if you compute
resistance. Cable resistance 1/10 of nominal speaker impedance may be good.

                                             xvlk

tony dB

Long run of speaker cable: to shield or not to shield
« Reply #5 on: December 27, 2004, 08:42:06 AM »
PRR, i'm with you all the way.

(Unfortunately?) i see a lot of gtrplayers enter my studio with Monstercable (made especially for speakers!) what is a coaxtype of cable. The inner isolation is very thick compared to gtrcable, but i always wonder if it isn't a better solution to use ordinary electricitycable instead of these very expensive monsterleads?

Cheers,

Tony

Category 5

Long run of speaker cable: to shield or not to shield
« Reply #6 on: December 27, 2004, 02:43:37 PM »
I just mesured the resistance of my "budget" copper stranded speaker cable and compared it to some Monster speaker cable.  Both seem to be about 16 guage.

There is no real measurable resistance in either, and the cable length is about 16 feet.

I would imagine that when running decent copper stranded cable the connecting point between the wire and Banana plugs, or speaker/amp terminals will probably make more of a difference in sound quality than the actual wire itself.

The cheap speaker cable I am using now was purchased at Radio Shack, and hear no difference between it and the monster cable.  I switched it because the monster cable looks like it is starting to tarnish all the way through (turning dark).  I imagine this doesn't really affect sound much except at the conductive ends.  Either way, I can't imagine that $100 speaker wire can possibly sound any better.  Especially with runs under 50 feet.

Shane

Gus

Long run of speaker cable: to shield or not to shield
« Reply #7 on: December 27, 2004, 03:10:38 PM »
The tarnish is most often the PVC coating not being right.  IIRC the C attacks  the Cu.

Long run of speaker cable: to shield or not to shield
« Reply #8 on: December 27, 2004, 03:43:45 PM »
Quote from: "Category 5"
I just mesured the resistance of my "budget" copper stranded speaker cable and compared it to some Monster speaker cable.  Both seem to be about 16 guage.

There is no real measurable resistance in either, and the cable length is about 16 feet.

I would imagine that when running decent copper stranded cable the connecting point between the wire and Banana plugs, or speaker/amp terminals will probably make more of a difference in sound quality than the actual wire itself.

I can't imagine that $100 speaker wire can possibly sound any better.  Especially with runs under 50 feet.

Shane


I can not imagine it with You, it is some HiFi mania with no real background.

But you can measure everything. There are two methods (with the
some back) for measuring small resistances:
Thomson (Lord Kelvin) s bridge
and
Ohm method.

Ohm method can be simple if you are not going to metrology Lab every day.
Have a cable and make two ports (with some small distance) at the every
end.
If you connect outer ports to current source (Voltage source with
resistance of magnitude order bigger than cable in series, but it is nor rule.), you can
measure current (by ammeter).
To the inner ports you can connect voltmetter.
By Ohm s  law, you can compute resistance:
R=U/I.
And voltage drops at the outer ports are not included in measurement... .


                                   xvlk

tony dB

Long run of speaker cable: to shield or not to shield
« Reply #9 on: December 27, 2004, 03:48:34 PM »
need to read a few times again i'm afraid   :?
or need to read the art of electronics real soon  :grin:


PRR

Long run of speaker cable: to shield or not to shield
« Reply #10 on: December 27, 2004, 06:31:46 PM »
> Monstercable (made especially for speakers!) what is a coaxtype of cable.

Does it really have one conductor surrounding the other? Or is it parallel-pair with heavy round jacket and maybe "Magnetic Flux Tube" (probably carbon-loaded plastic) around it? Impossible to tell from Monster's websites which are all hype with no clear details.

> Cable resistance 1/10 of nominal speaker impedance may be good.

In non-critical use: I agree. Actually I have sized speaker cable resistance as high as 20%, even 30% of speaker impedance, when I was poor, it was a one-time job, I had spare power, and had EQ.

But it has become customary to pick amplifiers with a Damping Factor over 40. That means the output impedance of the amplifier is like 8Ω/40= 0.2Ω. If the speaker's response and impedance were balanced for a zero-ohm output, a 0.2Ω output is only 0.25dB different, inaudible. Note that a Damping Factor of 10 (as with your Z/10 suggestion) is at worst a 1dB error, mostly at frequency extremes where room effects cause 5 or 10 dB errors.

For "OK" damping, 10%/1dB power-loss/response-error, 1Ω wire resistance, in USA-size (and approximate metric diameter):

#18 (1.0mm) 75ft (23m)
#16 (1.3mm) 122ft
#14 (1.6mm) 190ft (58m)
#12 (2.1mm) 300ft
#10 (2.6mm) 490ft (150m)

For Damping over 40 (assuming the amplifier damping is way over 40, which is now common) 0.2Ω, cut the above lengths to 1/5th. A 100 foot run with high damping in 8Ω needs #10 wire.

Note that many popular-price speaker terminals won't swallow #14 wire. 1950s-style (Dynaco) screw-strips will need crimp connectors. The press-lever terminals on mass-market hifi amps can have their holes reamed to barely take #14 (I installed a dozen of these that way). When you need fat wire in a small connector, solder a couple inches of #16 to the end of the fat wire.

For lowest installed cost on permanent runs, use solid house-wiring cable (ignore the bare lead) and use short runs of smaller stranded wire at the ends so vibration and repairs don't crack the solid wire.

If two speakers are in about the same place a long way from the amp: you can get house-wire with 3 hots and a ground. Colors White, Black, Red and bare. The ground is bare but has ample insulation while inside the jacket, and up through #12 the ground is full-size: it can be used as a "live" wire. Such a cable in #12 size is called 12-3-G. Make the long run with this, then splice to stranded 2-conductor wire to get to the speakers and amp terminals. (Note that above #8, NEC allows the ground conductor to be smaller than the "current" conductors: 6-3-G will often have a #8 or even maybe #10 ground conductor.)

strangeandbouncy

Speaker wire
« Reply #11 on: December 27, 2004, 07:16:34 PM »
i have installed loads of pairs of speakers in studios worldwide over the last 20 years. i have NEVER heard of shielded speaker wire. 18yrs ago we tried different thicknesses of Oxygen free against similar thicknesses of industrial installation cable, over a 150' run, in an actual studio installation. Can't say that there was much in it. Bigger is better, and Oxygen free is subjectively a tiny bit "Sweeter". I have frequently "replaced" someone's speaker cable, merely cleaning the cable ends, and tightening the binding post. This makes the greatest percievable difference in my opinion! They dont believe you 'til you show them.
Welcome to the world of The Emperor's New Clothes . . . . I have heard people swerar that 1m of Single-crystal-linear-oxygen-free-solid-silver-plutonium-coated-ball-sh*t makes all the difference, yet can't tell that their speakers are out of phase!(really!)

    Blah Blah Blah,

       Just my hard-earned practical hands-on experience . . . .


         Andy P
. . . . RUH ROH . . . . .

Re: Speaker wire
« Reply #12 on: December 27, 2004, 08:12:20 PM »
Quote from: "strangeandbouncy"
Oxygen free

Oxygen free copper is good for making tubes.
I do not know, how improve it electrical parameters;
I mean, that it is impossible to change 10 percent in resistivity.
there are other chemicals in copper than oxygen,
and they can modify mainly mechanical parameters.

... And mechanical parameters. They are widely changed
by copper recrystalisation.
In direct metal mastering disc cutters, they are used electrolytic
copper. And after electrolysis, copper blank disc are stocked in
refrigerator. ... maximally three days.
For a longer time they are so rigid, that Neumann cutting machine
can do good cut into they.

Buy copper cables in the winter and maximally one week old
and put it the some day you buy. And listen it in the refrigerator :-)


                             xvlk

tony dB

Long run of speaker cable: to shield or not to shield
« Reply #13 on: December 28, 2004, 06:41:55 AM »
PRR, don't have too much time rightnow, but YES, it is shield and core, not 2 inductors parallel.
btw GOTHAM speakercable is coax too.
http://www.gotham.ch/gac/gacindex.htm and select speakercables in the lefthandside box.

Used in a lot of installations. More examples can be found

PRR

Long run of speaker cable: to shield or not to shield
« Reply #14 on: December 28, 2004, 06:44:32 PM »
> GOTHAM speakercable is coax too. http://www.gotham.ch/gac/gacindex.htm and select speakercables

Their "Highend balanced audio signal line ideal for active loudspeaker" cables are shielded. These are of course really line-level cables, not speaker signal-power cables. Conductor size is small, too small for most speaker-runs but fine for medium-Z lines. Capacitance is similar to most coax: around 30pFd/foot.

Their "High flexible Speaker cable" is just parallel or twisted pair inside a round jacket. Capacitance is not specified but is probably less than 10pFd/foot.

And then there is their "Quaxial speaker cable" which sure is a coax construnction in speaker-power size, with an astonishing 150pFd/foot capacitance. And the verbal description seems like random buzz-words thrown together.

tony dB

Long run of speaker cable: to shield or not to shield
« Reply #15 on: December 29, 2004, 05:27:56 AM »
loads of hype a no real quality then? Due to the construction i mean.  :?


 

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