About multiplating, skin effect and stuff

Are there further benefits to plating conductors with other noble metals in addition to silver?
I was thinking that since the skin effect for HF transmission is usually mitigated with silver plating, how about a multiplating consisting of materials in order of decreasing resistance, with silver being the outermost layer?
Would this be superfluous with the silver gobbling up all the HF anyway, what with electricity following the path of least resistance? Or would this actually give way for a wider radial distribution of the HF range? If so, would there be a direct relation to how resolving the cable would be?
What about a similar solution with a thicker alloy plating whose resistance drops linearly from that of Cu to that of Ag towards the conductor’s outer surface? Is something like this metallurgically challenging? Essentially a gradient-like alloy that transitions homogenously from Cu to Ag (for example).
I’m not knowledgeable but what comes to mind is a Cu-Ag alloy (called billon apparently) metallurgically engineered to have an increasing silver atom content radially outwards. Sensible?

What comes to unplated pure silver…
Do there exist interconnect patents based on encasing the exposed silver in a near vacuum? Something else? Surely there’s ways to keep silver oxidation in check… Right?
Imagine a whole audio chain consisting uninterruptedly of monocrystalline silver. I take it that it can’t get better than that with non-superconducting metallic conductors? This drives me to think that surely someone out there has such a signal chain… Wouldn’t even be all that far-out.
What comes to superconductors, all I have to say is if I some day work at CERN it’ll be my first priority to build a high-end setup running on cooper pairs (heh).

And about hollow (tubular) conductors… Does the skin effect still apply only radially outwards or does it apply for the inner surface also, increasing the skin effect area? If not, is it possible to design a conductor geometrically such that skin effect area is maximized compared to a round conductor? I do have a hard time imagining such a geometry without complications arising from irregular resistivity, but then again a sphere can be turned inside out in three dimensions.

Also, could someone please explain the phenomenon of surface oxides causing rectification in a conductor? It’s been bugging me since “a famous person” in one Munich High End presentation explained why carbon nanotube conductors are far superior to copper because an oxidized copper conductor acts as a rectifier.
Back then he also adamantly proclaimed that C nanotube cabling is “not available”… Is it already available?

Excuse my lack of knowledge, I like making hypotheses based on intuition and having my intuition put in check by affirmation and correction.

pm your mail address for a hint. You‘ll need money.

Excuse me, I didn’t quite understand. Money, yes, sure… But is your hint regarding this too sensitive to share on the forum?

parts of it yes, and I don’t want to be too advertising or repeating for a manufacturer, but let’s stay with the easy one:

read a bit into their cabling. They among others do a molecular treatment (much different/stronger than the cryo concept) which among other further measures cares for a superconducting signal transfer, quite independent of conductor material. Different world than what you might have heard yet, especially when the whole chain is fitted.

https://schnerzinger.com/english/

Interesting! Will read into it.
I wonder if the concept of higher conducting material being better at transmitting interfering fields is related to a problem I had with my Audeze headphones cabled with rhodium-terminated full silver cables picking up TV audio channels from the air all across my living room. A quiet but very discernible TV broadcast that was not affected by gain.
The manufacturer said it’s impossible to be the cable’s fault since it’s double shielded. Hmm. (Old block house, mainly ungrounded, old leaky antenna network in the walls…)
The problem did exist with stock Audeze cables already, but was perhaps even worse with the upgrade. If rhodium really does have higher HF extension than, say, gold, is it possible it was precisely the 1/4" rhodium plug that was the culprit? I mean, I know it was, but because of the material?
Worth mentioning the interference wasn’t ground-based, it was present with any source in the room, even the phone. Didn’t have any balanced headphone outs available, sadly.
I did have poor quality power strips in series at the time that might have further amplified and spewed the interference. Will have to test again when I get my Audezes back, now that I’ve got a single high quality power strip with significant RFI attenuation.
If the interference persists, is my only option getting a balanced HP amp with dual XLR outs and a new cable to fit?

Also, could someone please link to a chart comparing the frequency bandwidths of commonly used conductors?
I have seen mentions of rhodium having higher HF extension than gold for example and that correlates with the numerous mentions of gold having “warmer” tonal character than rhodium. Such comments were actually from a thread about comparing power sockets and plugs with different platings and base metals. So quite fundamental in a sense.
Would love to see some actual measurements.

Rhodium is certainly one intriguing metal.

To hear an RF broadcast, even if you are picking it up, you need a degree of rectification. I would be inclined to check all the contacts and clean them scrupulously.

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I’m sure the contacts, both the mini-XLRs on the headphones and the 1/4" plug were free of any stain. The rhodium doesn’t oxidize either…
How exactly could a premium-built, double-shielded silver cable with Furutech rhodium terminations act as a rectifier? The RF was audible as soon as the phones were plugged into any headphone output, even at 0 gain.
Can the system comprising the planar-magnetic headphones, the cables and any TRS ground, in the vicinity of the RF source somehow cause rectification? Apparently so. I wonder how.
The interference was solely noticeable with the Audezes. None of my dynamic headphones produced any audible interference.

Is there credibility to the notion that an ordinary silver-plated copper conductor “truncates” the outermost HF bandgap into a relatively thin silver plating that, while having lower resistivity, doesn’t quite have enough lattice space for optimal current flow?
If it’s a sensible shortcoming, what are some conductor topologies that allow for a significantly deeper inner spread for the skin effect current and prevent dumping the highest frequencies straight into a lower resistance plating, assuming there’s one?

Hypothetically how would a conductor with precisely calculated radially, exponentially lowering resistivity from center to surface behave (calculated to match the original skin effect current’s area of smear)?
So an alloy with continuous decrease in resistivity. Doping with suitable noble® metals in increasing atom concentration nearing the surface? What is metallurgically easiest, I really have no clue.

Please be so kind as to correct me if I’m making wrong assumptions.

Please, please explain in detail how a cable can act as a rectifier and to what extent, and how this physically affects the signal?

I don’t know the exact effect but that would presumably be a fabulously engineered (and fabulously expensive) cable :slight_smile:

It is junctions that can act as a rectifier - so any change of metal, especially where there is any corrosion / oxidation - you end up with a metal/metal oxide junction, which is exactly what early rectifier diodes were made of. In fact the original “diodes” were the “cat’s whisker” in a radio - used to demodulate AM radio signals in those early radios to produce an audio signal from the radio wave picked up by a long wire aerial.

A powerful commercial radio broadcast (or a local amateur one) that is picked up by some or other audio interconnect that is poorly or improperly shielded / earthed, or that radio signal is actually picked up the the screen of the cable, and instead of going off to earth, some of it ends up on the signal line where if it encounters any non-linearity (such as the accidental “cat’s whisker” mentioned above) it will produce an audible version of whatever audio the radio signal was carrying. A very badly biased audio amp can be sufficiently non-linear to demodulate the radio signal too, it’s a wonder we don’t have this sort of problem more often.

Mitigations include good quality earth connections, well shielded cable, and lower impedance inputs, but that last goes against the usual method of ensuring cables have a minimum effect on frequency response which is to have higher impedance inputs.

I seem to have rambled, sorry, it must be my bed time :slight_smile:

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Thanks for explaining.
So is it only oxide-oxide junctions where it happens? The 1/4" plug on the cable is rhodium plated so only the copper contacts inside all my hp outputs could contain oxide. Hmm, I doubt the mini-XLR connections on the Audezes are oxidation-prone either…
But as has been stated, there is mandatorily rectification happening somewhere along the line. Soooo… I should apply isopropyl alcohol to all contacts as a first step?

Pretty much any “dirty” junction - metal against metal oxide can do it.
Personally I use Servisol switch cleaner, but that is a bit gunky…

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Okay, so apparently the part about a gradually transitioning Cu-Ag alloy is nonsense - doesn’t work because different sized atoms added into the lattice only impede electron flow.

Anyone know of existing methods of creating a material whose resistivity changes gradually? If not, please throw some hypotheses.
Would such a material actually allow for higher bandwidth and other benefits in a conductor by spacing the HF range more broadly, radially?

So what about this:
Copper as the conductor’s core, plated with silver, then a layer of copper thicker than that, then silver again, and so on, such that the layers of copper get thinner towards the outer layer thus allowing the spacing of silver layers to get denser and denser?
Would this work to mitigate the skin effect in any noteworthy manner? Is a hollow conductor still a much more reasonable solution?

I’m liking the thought of some 15mm copper pipe actually, would look great too until it goes dull coloured.
…even better the 8 or 10 mm bendable pipe
Not sure on the conductive quality (purity) of plumbers’ copper though…

No but seriously, what do you think?
Have the sensible mitigations for the skin effect all been applied already, and do my hypotheses have anything to them?

I used to bend brake lines and it seems one could do the same thing using a mandrell with copper solid or tubular so it could be routed from component to component and jacketed in something to act as a oxidation shield, even clearcoat. Then hammer the ends to form spades so no interruptions in the conduction.

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I have made that suggestion before, probably in Paul’s Posts. I confess to being slightly tongue-in-cheek.

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