Riddle me this: how is carbon a conductor?

FWIW, carbon filaments are common in automotive spark plug leads. They generate less radio interference than stranded copper. Back in the 60's and 70's racers replaced carbon filament for stranded copper because copper is less fragile/more reliable under extreme conditions. YMMV :^)

van den Hul has used carbon and carbon-metal hybrid conductors for years. With respect to its application in ICs, the high resistance is of little consequence since you are dealing with low current. On the upside, carbon is RF transparent, will not degrade over time due to oxidation, and the filaments used are so thin that they have virtually no skin effect.

Oxia,

Carbon's RF transparency is directly related to it's conductivity!

Rock,

My understanding of carbon in spark plugs is that it is used *because* a spark gap is and extreme situation. An interconnect, however....

Herman,

Now my physics gets a little foggy (or perhaps it is the beer :-), but you do raise an interesting question. My inital cut is that for the resistance (which is important to IC's) is 1000 times greater than the other conductors (assuming equal conductor area and length). Thus, this presents a 1000 greater load on the source component. Moreover, if you're using carbon along with these other conductors, the effective resistance chucks the carbon component of the "conductor" into the noise: it's the metals which will relay the signal to the load.

So why is it there?

Let's just say we have 10 the cross sectional area of carbon over the metals. We still have 20db less signal being passed through the carbon. At this point, don't conductor geometries play a larger role in what is audible?

Thanks,

Carbon is more of a resistor than a conductor. That's why older resistors were made out of Carbon. That in itself should tell you about how conductive it is in comparison to Copper or Silver. Since resistance equates to thermal losses and thermal losses equate to signal losses, one would have to be silly to use Carbon as a conductor within the confines of what was supposed to be a low loss / high resolution audio system.

If one doubts this, take a look at this chart that compares the levels of electrical conductivity between various elements. Whereas Silver is at 62.9, Copper is at 60.7, Gold is at 48.8 and even "lowly" Aluminum is at 37.7, Carbon is down at 0.07 !!! In effect, even Rhodium, which is a poorer conductor than Aluminum is at a conductivity level of 23 and is used on many different "high end" RCA's, spades and power plugs, is still 328 times more conductive than Carbon!!! Comparing Carbon to Copper ( 867 times more conductive ) or Silver ( 898 times more conductive ) is ridiculous to say the least.

As such, if one is worried about having clean RCA & speaker connections while they are using a Carbon based conductor in their system, they are wasting their time. You could literally coat your connectors with a hair thin layer of mud and they would still be more conductive than carbon. In effect, using carbon as a signal carrying device would be no different than dissipating / wasting signal in a resistor that wasn't necessary to the stability of the circuit. Kind of like spending money on something that you didn't need or wasn't beneficial i.e. a big waste with very little redeeming properties.

An 18 gauge copper wire has .0209 ohms of resistance per meter. That means carbon at 867 times more is 18 ohms. Using a larger cross section of carbon would reduce this even further. A 10 guage carbon fiber would be 2.6 ohms/m. I don't know what the diameter of the fibers in this cable is, but is 18 ohms detrimental to the sound? A better question may be would the advantages outweigh whatever disadvantages there may be? I don't know, but 18 ohms is certainly much, much lower than the 25K to 100K input impedance of a typical component. It is about .2% of even an unusually low 10K input impedance.

The source wouldn't see a greater load. Actually the opposite. The resistance would be in series with the output so you would have to turn up the volume a bit (a fraction of a percent) to get the same voltage level delivered to the load, but it would still draw the same current.

Sean, you make the claim that it is a big waste with no benefits. If you go to his website he claims that there are significant benefits, and unless my math is wrong there is very little waste.

The bottom line is: does it sound better? I really don't know the answer to this since I've never heard the Wolff cables. I am simply challenging the assumption that a few ohms of resistance is a bad thing. Of course if it gets too high then that could be an issue, but what is too high?

Here is a quote from the Audience website with a their take on cable resistance. I am presently using Audience cables and think they are very good, especially for the money.

"There is a common misconception that loudspeaker cable must be large in diameter and have a low DC resistance in order to provide good bass response. DC resistance is relatively unimportant. What really matters is the characteristic impedance (AC resistance) of the cable. Music is an AC signal after all. Most of these large diameter/low DC resistance cables have excessively high characteristic impedance anywhere from 100 to 600 ohms with some measuring in the 1000’s of ohms. The Au24 Loudspeaker Cable is only 4mm or 1/8" in diameter. Although the DC resistance may be slightly higher than the garden hose variety speaker cables the characteristic impedance is only 16 ohms. Musical signals from the bass to the overtones pass through this cable with less actual impedance than a cable with a lower DC resistance."