Im no physicist but a gas, sodium hexafluoride, seems to qualify as a great dielectric.
I saw a demonstration on the "Tonight Show" where a firing stun-gun was placed in a fish tank full of this stuff.
The spark WOULD NOT arc from one side to the other!
This had to be several thousand volts?
I'm sure the gas could manage to contain the electrons in a speaker cable.
Also, Mr. Leno stuck his face into the same tank to listen to the gas lower the timbre of his voice.
While this is cool by itself, it demonstates that the gas is non-toxic.
I wonder if anyone has tried using this for audio?
Teflon (PTFE) is better than most, and found in Nordost and other high-end cables. Air separating the Teflon is better still. Certain [noncombustible] gases even more so.
Yes- A vacuum is the best. BUT- Containing vacuums and gases is tricky/expensive, and therefore not often practical (http://www.taralabs.com/images/31479_eprint.pdf). Some manufacturers create a foam of a plastic and air which does work well. Teflon is usually considered the best(after vacuum/air/distance) in any dielectric application.
Of the materials typically found in audio cables, natural unbleached cotton is closest to air in dielectric constant. Teflon and polyolefin are good practical alternatives thereafter. Polyolefin heat-shrink tube is stronger than teflon & easier to work into DIY designs.
natural unbleached cotton is closest to air in dielectric constant.
That is a common misconception because people google dielectric constant and wind up here:http://www.asiinstr.com/technical/Dielectric%20Constants.htm
a company that makes instruments for measuring bulk solids, the number given is for raw cotton very much like a cotton ball and has a high ration of air to solid.
This is a much more relative site for finding information on cotton as used in our field:
A Swiss textile company:http://www.swicofil.com/products/001cotton.html#Properties
as you can see the dc for cotton made into a usable form, similar to what would be covering a wire is between: 3.9 7.5
what cotton does do well is reduce mechanical vibration which is why it is used frequently as a cable filler. It is also hydrophilic which is not something you want next to a metal conductor.
Microporous PTFE & PE and solid PTFE is for all practical purposes the best dielectrics to use. A tube filled with nitrogen would be great but not very practical to manufacture, a vacuum even less so.
Ah, but a tube filled with liquid nitrogen would be even more intriguing, especially if the wire it surrounded was made from one of the high-temp superconductors. Imagine the look on your buddies faces when you topped up the liquid nitrogen in your cables before your local audio club's next listening session! Mmwaaahaahaahaa!
AFAIK foamed Teflon in oversized tubes gives the lowest dielectric constant close to 1 (air).
microporous ptfe is 1.4 - 1.5 depending density, no oversizing, that's good for gases not solids, it will only increase dc..
This is the most complete table of dielectric constants I have found.http://www.clippercontrols.com/info/dielectric_constants.html
Anyone know a more complete source?
Oversizing should lower dielectric constant since air has lower DC than teflon. As for the difference with IC or speaker cable - capacitance of the wire is straight proportional to area and dielectric constant and reverse proportional to distance. Some teflon IC have as lo as 3pF per foot while typical shielded generic cable has about 25-30pF per foot. Dielectric absorbtion (proportional to dielectric constant and lowest for the teflon) is a process of storing some energy in capacitor's dielectric. Completely discharged capacitor can charge itself back recovering energy from dielectric. It is usually very slow and I don't know what effect it has on audio signals.
AFAIK foamed Teflon in oversized tubes
Oversizing should lower dielectric constant since air has lower DC than teflon
The first quote would indicate oversized tubes filled with microporous PTFE, perhaps you meant, 'made of', which would go along with the second quote.
exposure to the atmosphere and having a loose conductor are draw backs to this but yes the dc is lower
There are several manufacturers using rectangular conductors with the narrow sides within a teflon tube. This means that the majority of the conductor has an air dielectric or in the case of the Stage III with a vacuum dielectric. Townshend is the other manufacturer that I know of. I also have some ics with a silver wire spiraled within a teflon tube also minimizing the conductor's contact the teflon. These were made by Bogdan.
Cpk - there are several cables made with oversized tubes (most of Audioquest, Acoustic Zen). I'm not sure if tubes have air or nitrogen inside. Material of the tube itself can be polyethylene, foamed polyethylene, teflon, foamed teflon - depending on the price of the cable.
On my sensitive system, dielectric's very audible noise is proportional to the thickness of the dielectric.
The conversation here says to me the idea of minimizing dielectric presence has caught on. That is a good thing.
I use a very short, very very thin 12 gauge ribbon for my SCs. to prevent shorting, I loosely wrap the ribbons in saran wrap. This is very thin, and it touches the ribbon in few places. It works. I don't hear any of the haze and fizz I hear with commercial SCs.
Muralman - additional problem with speaker cables is skin depth. There is no skin effect down to gauge 18 within 20kHz audible range but my cables are gauge 7 (necessary or not). Splitting conductor into many (isolated) helps since surface area is increased but effect is still there (combined magnetic field is increased). Now the trick is to arrange wires in pattern minimizing addition of magnetic fields. Audioquest does "Hellical", others have different sometimes strange looking schemes. Acoustic Zen has over sized Teflon tubes (air tubes) with multiple conductors (about 10) plus one with multiple strands. Weave pattern is sort of hellical.
Have you tried Au24 - it has very thin dielectric?
Kijanki, the proof is in the playing. Having been trained in the sciences, I look at the job the SC has to do and formulate a best means to assist the SC in it's job.
It was hearing a Shunyata Helical SC that convinced me I had to find a replacement for my magnet wire.
What I figured is, the music signal is running at near the speed of light in a wave pulse form. giving the signal a lot of pathways with varying currents of mirror signals seems counterproductive. I wanted a very thin ribbon because I did not want wire crosstalk, or the intensely small music wave to bounce around a solid wire.
The woven strand wire I dismissed out of hand due to having tried many forms. The theory is better than the practice. The solid magnet wire had very special midrange. Somehow the solid wire resists the highs and lows to a certain degree.
Ribbons proved very successful in systems I am familiar with in Europe. They are easy to try. The copper ribbon I chose is .003" thick. I turned my monos around to make the SCs as short as possible. That way, I didn't have to worry about capacitance.
All I had to do is prove my hypothesis. When I hit play on my transport I literally fell backwards as the huge stage changed burst upon me. The proof was more than I dreamed of. Highs and lows opened up, depth blew out into the wilderness, and detail detail detail.
Obviously my 1 ohm speakers are getting all the current they crave.
Muralman, you are going down the path taken by Omega Mikro some time ago.
Tbg, danged if you aren't right on the money. The boxy endings caught my
interest. Making the transition from wide ribbon to spade required some
necking. I shrink wrapped the ends. I have no intention to sell, so no worry.
Somebody showed me Mapleshade has ribbon SCs too. Looking at the prices
shown for both I am delighted to have found a way to make something
functionally identical on the cheap.
Kijanki - yep, I am fully aware of that and like I said they have their drawbacks.
You ask good questions, ones that I don’t know how to answer, except to say none at all. Being impractical, what I can offer though is the Fluorinated Ethylene Propylene (FEP) found in Nordost is better than most, but that is the gapped sleeve and monofilament (spiral wound/point contact) and air is actually the (better) majority of the dielectric. In my experience, these cables can’t be beat for tonearm to phonostage transmission. I haven’t found anything faster or less colored. Some may choose cabling as a tone control beyond this point, but source retrieval deserves the most transparent and honest of cables IMO.
Silversonic/DH Labs has a dielectric on their Air Matrix Cable that is a Teflon material that is actually 70% air. Think of it as a less dense Teflon foam.
I believe Chris Sommovigo of Black Cat Cable/Stereovox/Stereolab and Kimber designs etc. used a braided foamed aeron material as well in his later Lectraline series, again lots of air for the dielectric present!
Some reasons to admire a design such as Anti Cables are (1) no dielectric, (2) no jacket, (3) no shielding, (4) high purity copper and last but not least, (5) directional ARROWS.