On the other hand, why do you feel that lower resistance would be better?
31 responses Add your response
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.
Carbon's RF transparency is directly related to it's conductivity!
My understanding of carbon in spark plugs is that it is used *because* a spark gap is and extreme situation. An interconnect, however....
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?
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 1000s 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."
A material can be broken down into one of three categories, a conductor, a semiconductor, or a non conductor(insulator).
Metals are conductors, which is why we often mistake conductors as having the characteristics of the good conductors(silver, copper, gold, etc.). We sometimes forget that things like W(tungsten), used in light bulb filaments are not good conductors.
Semiconductors have two natures; sometimes they are non conductors, and sometimes they are conductors. While this seems hard to understand, consider a material such as tin oxide, which is an insulator. Pure and simple, it will not conduct electricity. But, dope it(add a VERRRRRY minute amount of) with things like platinum or palladium and it WILL become a conductor when placed in the presence of a reducing gas. In English, this is how carbon monoxide sensors and breathalyzers work. In the presence of CO or alcohol, the conductivity of the doped SnO2(tin oxide) skyrockets, and this sets off the alarm.
Resistors ARE conductors. Let's get that out of the way from the start. And, conductors ARE resistors. The best conductor, silver, can be used as a resistor, but you would need a very long length of it to do the same job of resisting the electrical flow as a very short length of a more traditional resistor, such as carbon, palladium - silver, or ruthenium.
So, after this way too long babble I have put forth, carbon is, FOR SURE, a conductor. It's not as good a conductor as silver or copper, but it is still a conductor. Whether I would use it as a power cord or not, is irrelevant to this argument.
Well, Sean (welcome back), that's my point:
1) Why is carbon in the signal path?
2) Given that carbon is ~30db poorer in conducting the signal: are we not hearing differences in the the conductor geometry and dielectric loading of the cable? (which are material to the sound of a cable)
Impedance is a combination of capacitance, inductance, and resistance. The best you can hope for in a complex conductor is to make it purely resistive, so you're still left with the physics of carbon being a poor conductor. (which is why it rejects RFI & why they use in in the Stealth, and all the other nonrelevant "technical" descriptions loop back to conductivity)
Herman: Are you actually reading what that article says and understanding it or are you taking it at face value? A child with basic electronics knowledge could tear that article apart piece by piece.
Since the link that you provided primarily discusses AC, i'll stick to that. Suffice it to say that showing some type of a picture-graph of a 480 millivolt square wave at 6 MHz has very little to do with how well a given product / conductor will perform at 60 Hz and / or near the audible range passing a Sine wave.
As far as i knew, people were using filters / power line conditioners / regenerators to try and narrow the bandwidth of the AC path. According to that article, it apears that we should be trying to achieve a wider bandwidth that would act as a more linear conduit for RFI to enter into our gear. After all, we want a pure sine wave that is very limited in bandwidth and nothing else.
How one could think that anything in that article ( pertaining to AC ) is beneficial is beyond me. With gibberish like this invading this forum, i'm going back on vacation. Sean
PS... To switch over to signal carrying cables, if you want to insert yet another source of signal loss into your system, why not just use a carbon resistor of the same appr value? You'll dissipate the same amount of signal with no chance of recovery. On top of that, you'll simply be adding to the divergence between input and output impedances between the mating gear. This reduces power transfer, increases ringing, slows transient response, etc... Then again, maybe they are counting on the "lossy" nature of this type of conductor to not only "lose" some of the primary signal, but also damp / absorb some of the reflections. I guess that we will never know as the people writing their ad text are not technically competent and / or they don't display any pertinent info to the subjects being discussed on their website.
mPrime, your math is flawed to say that you get 20dB or 30dB less signal passed through a carbon conductor. The ratio of carbon's conductivity to that of copper is not the proper way to look at it.
What we are concerned with is the amount of voltage that is delivered to the next stage. If a perfect voltage source has a 1 volt output, and I use a cable with 1 ohm of impedance hooked up to a 50K ohm input impedance, I will get 99.998% of that 1 volt delivered to the load. If I use a cable with as much as 1000 ohms of impedance I will still get 98% of it, which is -.18 dB.
As far as characterizing carbon as a "poor conductor," it has more resistance than copper but in the grand scheme of things it's really not that much. I looked at the Van Den Hull website and they state a 38 ohm/meter spec for their metal free, carbon fiber interconnects. This would result in -.006 dB/meter in the example above.
The reason I take this approach is that the souce component will drive the interconnect and it's target load. Thus, the voltage drop you say we are concerned amount is impacted by the IR drop across the IC. This isn't anymore complicated than Ohm's Law (Freshman Physics).
Look, I'm not trying to get into a peeing contest, nor am I looking to create a flame-fest. I'm trying to understand if a manufacture's claims are supported so I may make a determination to explore their product offering. In this case, I've come to a conclusion. BTW, my conclusion should not impact anyone else's enjoyment of Mr. Wolff's products.
Sean, lighten up :>) You sometimes seem to grab a mantra, such as lower resistance is better, and defend it to the death without even considering another perspective.
The issue is much more complex than how much resistance a cable has. That is but a tiny part of the complete picture, which I maintain there is much we don't understand. If we did we wouldn't have these debates ad-nauseum on topics such as is balanced better than single ended, is copper better than silver, are tubes better than transistors, is cable A better than cable B, CD vs. vinyl vs. DVD-A vs. SACD vs. my personal favorite, 8 track tapes ..........................
Open up your mind a bit and consider something besides that which you have convinced yourself is the truth and the only truth. When Monster started pushing cables in the early eighties we all laughed that a piece of wire could affect the signal at audio frequencies. Now we know better.
I don't know if these carbon cables are any good as I haven't heard them. Others say they are pretty swell. To condemm them on the basis that the resistance is a bit higher reminds me of all these people who won't eat rice because it is a carbohydrate, and they've read a bunch of sound scientific reasons why they are bad for you. I just got back from Japan and some of the longest living people in the world are a bunch of rice eating Okinawans
You defended the magnet guy in another thread and he offered nothing but the word of God to back him up. Hmmm, that sounded a little blasphemous. I think you should give the carbon guys a chance too.
There are a number of forms of carbon each with different physical and electrical characteristics. Think graphite and diamond. Graphite, the most common form is in the form of flat plates that have very different measurements depending on whether you measure across that flat surface or through the plate. Thus material processing can drastically alter the measurements if you process to align the crystals instead of allowing them to be random which is the common form measured. Technically graphite is a hexagonal crystal that tests quite differently along its central axis than across the flat plates.
Lapaix, just to make things clear, there are only two forms of carbon - graphite and diamond.
While I could joke about it here, the fact is that if it were a conductor, which it is not, I wouldn't be surprised if some high end audio company didn't try to make power cords out of it. But, I have already begun to see it used in loudspeaker drivers. The Liz Taylor collection of audio awaits us.
I just re-read my last post and I apologize because it looks like a personal attack on Sean. Maybe it is. I don't think that has any place here so I must apologize.
I'm afraid I've lost my patience with those who take dogmatic positions based on an incomplete understanding of the topics under discussion. I include myself and everybody here in that category because I believe that nobody fully understands what is going on with these systems. So for someone to take a position that the only acceptable spindle bearing design is one with the lowest friction, or that the only good cable designs are those with the lowest resistance, or a certain method of vibration control is the only one that will work, or any other such topic just seems totally absurd to me given the vast amount that remains a mystery in this hobby.
I think I need a vacation too so I'll be away for a while. Thanks for putting up with me.
Trelja made a very good point when he said
"So, after this way too long babble I have put forth, carbon is, FOR SURE, a conductor. It's not as good a conductor as silver or copper, but it is still a conductor. Whether I would use it as a power cord or not, is irrelevant to this argument."
We not only understand that carbon or graphite is of a higher resistance than thier metal cousins. Who says resistance is a bad thing. We certainly experience a lot of it right on this forum.(Joke)
Anyway, there are some characteristics that carbon has which make it a preferable medium to use. For instance, copper exibits frequency group delay in frequencies above 10K Hz. Carbon on the other hand is flat as a board up to 100K Hz. ten times that much. If you read about the super tweeters that are out they advertise frequencies in the 100K range. Can we hear 100K. Of course not. However, we can not hear 20 or 25 Hz. either, but yet it impacts the music as a whole. So the super tweeter manufacturer's are touting the same benifits at the highest frequencies. There is a review on Positive Feedback about such a tweeter.
Another person that has seen some benefits in using carbon is Steve McCormack. You can read about his carbon and siltech upgrades to his older amps at http://www.smcaudio.com/ .
The interconnects and speaker cables are a co-design between myself and a gentleman named Grover Huffman.
And by the way, Sean "I guess that we will never know as the people writing their ad text are not technically competent and / or they don't display any pertinent info to the subjects being discussed on their website."
I always love to see your ASSumptions.
Best Michael Wolff
A few questions for Michael Wolff: from what I understand, the conductive properties of graphite come from the way the carbon elements are arranged. The carbon graphite crystal is a hexagon with only 4 carbon atoms bonded. This leaves one outer ring electron free per atom to bounce around from atom to atom within the entire crystal. This causes the conductivity.
But does not this arrangement depend on the atoms always touching each other? And, wouldn't any stress or movement eventually weaken the material and cause some atoms to lose contact with each other (thus lose conductivity)? What is the life expectancy of your cables and does mechanical motion and normal electrical conduction shorten the life? Thanks for bearing with me.
Excessive stress and movement in any power cord or wire device would eventually cause a fatigue condition and which would lead to a mechanical failure. If the transmission of either AC power or a signal of any kind is dependent on the
the ability of the compound to share electrons, it would indeed cause either a degradation or failure.
We recommend just as any power cord manufacturer not to use your power cords (especially the expensive ones) as bolo whips since thrashing them around over your head does indeed shorten their life expectancy and could lead to tennis elbow.
Carbon has two natural crystalline allotropic forms: graphite and diamond: you are of course correct. Each has its own distinct crystal structure and properties. Carbon nanotubes and buckeyballs, however, are distinct allortropic forms of carbon, so there are more than "two" (although neither of the above two are germane to this discussion).
Here is a quote from a website: http://www.azom.com/details.asp?ArticleID=1630
You can read the whole article if you are interested. In this forum a technical discussion is surely not in order.
"Graphite derives its name from the Greek word "graphein", to write. The material is generally greyish-black, opaque and has a lustrous black sheen. It is unique in that it has properties of both a metal and a non-metal. It is flexible but not elastic, has a high thermal and electrical conductivity, and is highly refractory and chemically inert.
The unusual combination of properties is due its crystal structure. The carbon atoms are arranged hexagonally in a planar condensed ring system. The layers are stacked parallel to each other. The atoms within the rings are bonded covalently, whilst the layers are loosely bonded together by van der Waals forces. The high degree of anisotropy in graphite results from the two types of bonding acting in different crystallographic directions."
I don't understand the objection. It is simply true that the electrical conductivity of graphite depends upon the properties of the pi elecrons in the system.
Man, this thread has really taken off!
Tbg, from their website it's evident that the Wolff ICs uses carbon and silver. Presumably they don't use a pure carbon shield/return (for low shield resistance) and and therefore can get away with longer lengths.
I concur with your observations of the van den Hul First, which is particularly sensitive to ground current hum due to its high shield resistance (4.8 ohm per meter), especially if you have a "dirty" component with excessive voltage present in its chassis. However, when it works in your system, IMHO this cable can sound magical. In my experience, the vdH Second (which has carbon signal conductors and a metal shield) is quite unfussy about equipment matching or long cable runs. For these reasons I prefer it to the First.
To Herman and Sean, FWIW I don't see why you guys should leave this thread in frustration. You have both made valid and constructive points. I don't think anybody questions whether carbon is a poor conductor -- it is when compared to the metals commonly used, like copper or silver. However, I think the real question is whether resistance is of overriding importance in all applications. When it comes to ICs, since we are dealing with very low current, my opinion is that resistance doesn't matter that much. If your amplifier has an input impedance of 20K ohm, then to your preamp it will "look" like it's driving a 20K ohm resister. Given this situation, what difference will the extra few ohms of resistance in the interconnecting wire make? As Herman has noted, it is negligible. Other wire parameters can be of greater importance given your particular application, but rather than go on, I will cite a reference that tells the story much better than I can: