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Folks:
I purchased some fine uninsulated silver wire from A&M Systems a few years ago that I never got around to using. I am poised to start on two projects (a phono preamp and a preamp) where that wire could be used to carry the signal, but I have concerns about using uninsulated silver wire. Mouser has 3/64" flexible polyolefin heatshrink (part no. 5174-13643) that could be used to insulate the silver wire. Is this a good choice? If not, any recommendations?
Thank you,
Scott
Follow Ups:
"Polyolefins are the largest group of thermoplastics, often referred to as commodity thermoplastics, they are polymers of simple olefins such as ethylene, propylene, butenes, isoprenes, and pentenes, and copolymers and modifications thereof. The term polyolefins means "oil-like" and refers to the oily or waxy feel that these materials have. Polyolefins consist only of carbon and hydrogen atoms and they are non-aromatic. Polyolefins are usually processed by extrusion, injection molding, blow molding, and rotational molding methods. Thermoforming, calendering, and compression molding are used to a lesser degree. An inherent characteristic common to all polyolefins is a nonpolar, nonporous, low-energy surface that is not receptive to inks, and lacquers without special oxidative pretreatment. The two most important and common polyolefins are polyethylene and polypropylene and they are very popular due to their low cost and wide range of applications." from Polyolefin
They seem to have a dielectric constant of about 2.27
Regards
James
Hi.
I'd use teflon tubing instead silk or cotton, being so air permeable, to air-tight the silver wires from oxiation. Air-tightedness is key issue for pure AG wires.
Yes, I'll then put polyolefin heatshrink tubing on top for better electrical & mechanical protection in building AG ICs & power cords. They all sound good.
But for signal internal wiring, teflon tubing is good enough. IMO, no need any heat shrink tubing.
c-J
C,
What do you do to the tube to get an airtight seal?
.
tarnishing of high purity silver has never been a problem, even when exposed. Tarnish on silver conducts anyway, unlike copper. I have speaker wires and IC's I made in the earlier 1990's that are still just fine with barely any noticable change. The lower purity silver will have some sulfur and other impurities that will mess with it. I have always used teflon, .999 or .99995 silver. I have never sealed it because if there is moisture I really don't want to seal that in and I have found them better off to breath. This is my experience over the past 17 years of using and making high purity dead soft IC's, power cables and speaker wire.
The Elaborate DAC=Johnny's Balloon Meshplate 27 Balanced Preamp=Balanced Six Pacs=Newform Research 645
tarnishing of high purity silver has never been a problem, even when exposed. Tarnish on silver conducts anyway, unlike copper.
Actually the "tarnish" is silver sulphide, not silver oxide. Silver doesn't really oxidize much in air at normal temperatures.
But in any case, unless the surface is being used as a mechanical contact, I think people tend to freak out a bit too much about it.
se
Hi.
Precaution is always better than remedy given polluted city airs are not helping it. I'd not want to dodge the bullet considering my AG ICs & power cords are being used by audiophiles all over, some in in very hot & humid countries.
I always use min 4N silver. In fact I still keep a small piece of first sample of certified 0.99997 silver. It tarnishes like hell. Indeed I got responses from inmates in other forum which complained bitterly about the silver foil used as ground bus got tarnish bigtime quick. You're so lucky, bud.
I don't see any problem with moistures when buiding the cords. When shrinking down the polyolefin heatshrink tubing over the Teflon tubing holding the Ag conductors with a hot gun, the strong heat dries up any moisture ever trapped inside.
BTW, as I said above, air is the best dielectric next to vaccuum. Guess how I get air as dielectric for the AG condudctors yet still have the wires air-tighted from oxidation?
Take it as a quiz.
c-J
with nitrogen
If you have the wires stuffed into tubes, you can't really make a claim of an air dielectric.
se
Hi.
It only took me a little thinking. I recall I later came across a 25-year-plus major brandname IC & cords maker in USA claimed using the similar tweak to provide air dielectric for one of its high-end products.
Ideally pure free air dielectric is the best, so bare wire is the best. But we need insulation against electric shorting. So the second best is to use porous materials, like cotton, silk or the like porous materials, but then we start to worry about metal tarnishing due to moisture & chemical pollution. It happens to bare copper, let alone Ag.
We need to take a compromise btween air & insulation. Teflon is the best
choice being an excellent dielectric & air impermeable, pretty flexible (use thin wall type), & pretty affordably available in various internal diameter.
Simply choose Teflon tubing (I only use PTFE UL 600V rated, made in Germany for my Ag cords) of internal diameters many times larger than the gauge size of the single Ag conductor. By using hot gun to remove the moisture inside the tubing & sealed up both ends of the tube/exposed Ag conductor ends, an air-tight air dielectric environment will be provided for the Ag conductor inside the tubing.
How come? At any time, the round Ag conductor is only in one point contact with the wall of the round Teflon tubing. So the conductor is virtually bathing the dry air trapped inside the tubing !!
Of course, the next task is to provide mechanical protection to the Teflon tubing to ensure the Teflon tubing maintains its round shape at all time.
c-J
I had a sneaking suspicion this is what you were going to say which is why I hazarded the answer "You don't" in response to your quiz in your other post.
At any time, the round Ag conductor is only in one point contact with the wall of the round Teflon tubing. So the conductor is virtually bathing the dry air trapped inside the tubing !!
You seem to be overlooking something here. And that is that it's the electric fields , emanating outward from the surface of the conductors, which interacts with the dielectric. So just because the conductor is making point contact with the tubing doesn't mean you have an air dielectric. The dielectric isn't just that which makes contact with the conductor.
The fields are still interacting with the tubing, particularly in the region between the conductors where they're interacting with a double thickness of the tubing.
So no, I don't really see this arrangement as constituting an "air dielectric" in any significant way.
se
Hi.
Surely this is NOT true free air dielectric. Nor any cotton or silk stuff which are in contact of the bare conductor at all time.
But it would be much better situation in term of wave transfer delay due to dielectric reaction with the signal electrical field vs any solid insulation adhered skin-tight to the conductor at all time. We are talking about very weak electrical field due to weak signal level anyway.
Another benefit of this grossly loose tubing arrangement is it will subtantially reduce the cable capacitance (conductor+insulation) as air is least 'capacitive' (e=1).
Basing on the same priniciple, shielding should not be used in audio signal ICs.
c-J
right you are. I am working on levitating the conductor but so far it has only been successful in a penne pasta tube. Hey how come you couldn't help them out with the ac prong resonance issue? Mine ring like a bitch when in socket, or maybe that's the telephone.
Later ;-)
BTW, as I said above, air is the best dielectric next to vaccuum. Guess how I get air as dielectric for the AG condudctors yet still have the wires air-tighted from oxidation?
Take it as a quiz.
I'll take a stab at it.
You don't.
se
I wouldn't say it's necessarily a bad choice. Personally I prefer cotton or silk. If you want to use something plastic, why not use tubing instead of heatshrink?For something a bit out of the ordinary, Small Parts sells polyimide (Kapton) tubing with inside diameters ranging from just 0.002" to 0.16" and incredibly thin wall thickness ranging from 0.0005" to 0.003".
If you're going to use plastic, may as well use as little of it as possible. The thin walls that are possible with Kapton means less plastic. The wall thickness is so thin, it's almost on the order of enameled wire.
Good luck!
se
Also, both Michael Percy and Chung (VT4C studio) have teflon tubing in many sizes at very reasonable cost.
P
I'm placing orders with Mouser and Digikey, so this is a possibility if either carries the tubing. But why not use heatshrink? It's cheap and may fit more tightly on the wire. Is there an issue?
Hi.
This is a very common misunderstanding that insulation got to be tight given all wires come with skin-tight insulation/jacket.
NO, the best insulation is no insulation as free air is the best dielectric next to vaccuum. So the old way using natural material, like cotton or silk is some excellent choice as these natural materials allow air to flow freely in & out as if it were free air for the wire inside.
But Ag wires tarnishes so easily due to oxidation. Polluted city airs make things worse.
So we got to airtight the AG wires. Teflon (FEP, TFE & PTFE) tubing will be the choice as it is not so air permeable & best of all, it got very fast wave propagation velocity (vc) & very low dielectric constasnt (e), next to foam polyethylene & 3rd best to free air. Get thin wall tubing for flexibility.
Airtight both end of the tubing with the exposed Ag ends covered up with Ag solders. It's fun, but some demanding fun.
c-J
Well, if you just want something cheap to cover the wire, then the heatshrink will do just fine.
se
Many plastics are considered to have a "memory". They store the electrical signal and release it a short time latter. It is claimed this leads to a smearing effect of the signal. Teflon is your best plastic. The closet to teflon in a heat shrink is kynar but it requires very high heat.
If I was you I'd go teflon tubing (which isn't very flexible) or go with what Steve advises.
Russ
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