James Randi Posts $1M Award On Speaker Cables

The above is completely accurate when (as Jeff specifies) the issue under discussion is speaker wire. In the field of AC power distribution, however, skin effect does have an effect on conductor impedance.

70 degree C Copper, Skin Effect Depth Vs. Frequency: 20 Hz 16.1 mm 50 Hz 10.2 mm 60 Hz 9.3 mm 400 Hz 3.6 mm 5 kHz 1.0 mm 10 kHz 0.72 mm 20 kHz 0.51 mm 100 kHz 0.23 mm Source: So a 60Hz large transformer winding or buss bar with a thickness / diameter much larger than 19 mm (3/4 inch) just wastes copper.

------------------------------------------------------------- Copper, Maximum frequency for 100% skin depth: AWG Dia. (mm) Freq. OOOO 11.684 125 Hz OOO 10.40384 160 Hz OO 9.26592 200 Hz

0 8.25246 250 Hz 1 7.34822 325 Hz 2 6.54304 410 Hz 3 5.82676 500 Hz 4 5.18922 650 Hz 5 4.62026 810 Hz 6 4.1148 1100 Hz 7 3.66522 1300 Hz 8 3.2639 1650 Hz 9 2.90576 2050 Hz 10 2.58826 2600 Hz 11 2.30378 3200 Hz 12 2.05232 4150 Hz

Gnaw, that makes the sound slurred and sedated. ;-)

Tim

-- Deep Fryer: A very philosophical monk. Website @

So?

So?

There you go showing your ignorance again.

Since silver only conducts 5% better than copper, most of the reduction in resistivity results from the silver plating simply increasing the diameter of the wire a tiny bit. In the case of #12, the diameter increased from 80,000 uin to 80100 uin, ratio 1.00125, so the area increased by 1.0025, so the conductivity improves by about

0.25%, not too impressive when you consider that the tc will be 0.4% per degree C.

For fine-strand wire the plating is relatively thicker so the effect is larger. But wire manufacturers are no fools, and I wouldn't be surprised if the draw the copper a bit smaller when they know that they're going to plate it back up.

Since copper is a lot cheaper than silver, if you want conductiviry, buy bigger wire.

John

First command of Usenet... Thou shalt not command.

You are obviously not a wire man. Not only that, but you apparently do not know how to use your PC for much other than Usenet.

SPC Silver Plated Copper

NPC Nickel Plated Copper

TC Tin Plated Copper

SPHSCA Silver Plated High Strength Copper Alloy

NPHSCA Nickel Plated High Strength Copper Alloy

Specs? Any wire manufacturer's specs table on their website.

Are you lazy too? Gonna ask me for links? Get off your ass and look.

Naw... That's what SF6 is for.

Guy Macon posted to sci.electronics.design:

Except the improvement is not nearly as good as the table indicates. The B fields of the adjacent strands interfere with the skin depth calculations.

Not a very useful form of the data.

How about a table of resistance per foot versus frequency for each wire gauge?

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

No point in working much to prove that Always Wrong is wrong. 50 microinches of silver is never going to matter much.

John

SPC Wire has a lower Ohms per foot than Copper wire, dipshit.

You nym should be "NeverAdmitsWhenWrongAndAlwaysIsWrong".

Not that intelligent.

That's Dimbulb; absolute zero.

--
  Keith

Just get me an extruder and a proper die, and I'll insulate it for only $1.00/ft, after amorizing the $250K for the extruder and die. ;-)

In fact, with a little more sophisticated die, I could extrude two- conductor, and even put a stripe, which might take a small auxiliary extruder. I've seen extruders that you can pick up and carry.

Cheers! Rich

Usually, I UNroll it from the tube. ;-)

Cheers! Rich

The impedance is the same at all frequencies from DC to the frequencies listed in the table above. Skin depth is defined as depth where current is 1/e (~37%) of the surface value; this value was chosen so that in a solid round conductor, the decreasing conductivity with depth is balanced by the fact that all the points on the relatively large surface are using the same relatively small area at the center, which roughly balances the current density and thus makes the AC impedance roughly equal to the DC resistance -- flat frequency response.

(and many other places on the web) give the resistance in Ohms per kilometer and Ohms per 1000 feet, which is all you need at or below the listed above because of the flat frequency response.

In AC power there isn't much call for trying to push the wire diameter high enough for skin effect to become significant; by that point multiple parallel conductors are most often used simply because they are easier to bend. If you want to push past the skin effect limit, there is some information on modeling skin effect with a few curves here:

(I haven't had occasion to verify the contents of this page in real-world applications). A quick web search turned up this page that has some curves: (Again, I haven't verified (or even closely read) the webpage.) This fellow did some *very* interesting calculations:

Lurching back to the wild and wacky world of Golden Ears Audio, here is a fellow who makes his speaker cables out of CAT-5 cable. [

]. At least it didn't cost him much...

--
Guy Macon

SF6 is ecologically disgusting.

"With a global warming potential 23,900 times greater than CO2 and an atmospheric life of 3,200, one pound of SF6 has the same global warming impact of 11 tons of CO2. In 2002, U.S. SF6 emissions from the electric power industry were estimated to be 14.9 Tg CO2 Eq."

If I'm going to be successful at separating the GUM (great unwashed masses) from their shekels, it would be nice if the world would survive the after effects of my products. My products should at least be safe and sane, even if they don't do anything useful. Besides, I want to label the package with some manner of endorsement claiming my products are good for the environment because they are more efficient and therefore do not contribute more milliwatts to atmospheric warming.

I kinda like the approach that HP calculators and test equipment used before they cost reduced themselves into mediocrity. HP gold plated the traces on their boards. I dunno if it ever did anything electrically wonderful, but it sure looked great. I collect old HP calculators and sometimes like to show people what real quality looks like. They don't make them like that any more.

Some numbers: Material: Resistivity in ohm-meters Gold: 2.4 * 10^-8 Copper: 1.7 * 10^-8 Silver: 1.6 * 10^-8 Silver Sulfide: 1.5 to 2.0 * 10^-3 Silver Oxide: 1.0 * 10^+9

As for tarnished silver problems, I used to design marine radios with plenty of silver in the contacts and connectors. Protecting silver traces is easy enough, but silver contacts are not so easy. The rules were something like:

1. If the connection is wiping, leave it alone because the silver is soft and the contacts will break right through the tarnish.
2. If the surface is on a high power tank circuit, leave it alone as it has only a small effect on skin effect.
3. If the connection is a dry connection, had no contact pressure, and does not move, clean the tarnish off with chrome cleaner and protect it with a thin layer of wax.
4. If some idiot mixed gold and silver plug and jack contacts, the silver will leach through the gold and make a blackened mess. Replace both.
5. If the underlying copper is exposed, replate the contacts with electroless silver (silver cyanide). Clean up the mess with 10% acetic acid.
6. If it's silver cadmium oxide on the high voltage switches (used to prevent arcing), the contacts are usually made to be replaced.

As I previously mumbled, silver plated PCB's are invisible to the customer and therefore useless for the next wave of audiophile techno-hype. Even with speaker cables, silver plated cables are buried under the jacket, and lose their visual sales appeal. I suppose clear cable insulation and jacket would work, but even copper looks better than half tarnished silver. I don't think so.

If my speaker cables are going to sell, they have to impress the customer at the time of sale. It's well known that consumers value everything based on weight. Given two indistinguishable products, they will usually select the heaviest. One of the radios I designed turned out to be too light. So, we tinkered with adding a lead weight. That was a bit much for our dealers, so we settled on switching from light plastic bezels to cast aluminum bezels. Sale immediately improved.

What I was thinking is spent uranium speaker cables for the sound that will pierce armor. The resistivity of uranium metal isn't very good at 28.0 * 10^-8 ohm-meters (about 15 times worse than gold) but it can always be silver plated. What's important is that the resultant cable will out weigh anything available, and that's what drives sales to confused retail customers. Add some phosphors and it might even glow in the dark.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558            jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

If you want raw acoustic power, voice coils and magnets are insipid. I once worked on a battlefield speaker system that used a diesel powered air compressor and some Wagnerian (opera) size horns that could wake the dead. Well, actually I didn't work on the system much. I mostly swept the floor and cleaned up the wreckage.

Hmmm...not much detail. Anyway, the major design challenge was the fluidic modulator, which tended to destroy itself and spew shrapnel out the horns. When I left, the white lab coats were discussing exotic metals and ceramics.

I'm not sure that the audiophile market is ready for a realistic home Krakatoa simulation. As long as there are inefficient loudspeakers available, methinks the world is safe (for now).

Incidentally, one of my numerous jobs while attending kollege was selling hi-fi at a retail store. We were on commission and it didn't take long to discover that the markup on accessories and options was considerably more than the basic amplfiers and tuners. This was especially true for big loudspeakers. So, I arranged a little private demonstration. I connected a small 6 transistor AM/FM portable radio to the biggest and most expensive speakers on the floor and had it playing when the customer approached. The conversation would eventually drift to what was playing, where I would pull out the little radio by the speaker leads. I would follow up with "Now you know what's really important in hi-fi". Most customers were totally amazed and sales of high margin speakers were brisk until management decided to interfere.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558            jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

You should wee what the Germans were doing in this regard back in the WW II era.

Sadly, American homes are not typically installed with bidets.

Tim

-- Deep Fryer: A very philosophical monk. Website @

Sure they do! See [

].

:)

Also see:

_Soldering to Gold over Nickel surfaces- [

]

_Solder Joint Reliability of Gold Surface Finishes (ENIG, ENEPIG and DIG) for PWB Assembled with Lead Free SAC Alloy_ [

]

_Nickel/Palladium/Gold A Versatile Surface Finish_ [

]

_Direct Immersion Gold as a Final Finish_ [

]

_Wikipedia: Gold plating Soldering issues_ [

]

--
Guy Macon