The consensus on cross sectional area

What is today’s consensus on the true need for any substantial cross sectional area in anything other than power cabling?
Apparently analogue signals, from low voltage phono to high current speaker level, need not much cross sectional area to be efficiently transmitted, if the material and geometry are sensible. I’ve understood that cross sectional area is best minimized up to a certain point of trade-off. I understand a foil ribbon cable that trades minimal inductance for higher capacitance can shine in one setup and literally even fail in others, being an extremal case of near null cross section. (Like a capacitor turned inside out, some amps will oscillate without a correction circuit)

Since the mentioned near-null cross section foil-type speaker cables are succesful and praised products, apparently have no trouble driving high amperages, I am left to wonder why we bother with cross sectional area at all instead of simply focusing on geometry, metallurgy and dielectrics?

Also, is it actually skin effect in itself that even has much impact on SQ with designs made to eliminate it, or rather the well thought out general structure and LCR characteristics that come with such geometries? How could it possibly be audible, isn’t it more of an issue in radio applications? I do have hollow cables myself, which I enjoy, but I trust their strength isn’t in skin effect elimination because they still have enough outer radial gauge that I doubt very HF signal has much of an easier path, feels more like saving silver. But what do I know.

Seriously, is there actually global confusion on this subject, despite the precise mathematics we have to evaluate it?

If we do well with speaker cables with nearly null cross sectional area (foil), why is there consensus for the need for high gauge wiring? Is it very application specific or what?
I’d like to understand why ultra-thin foil is capable of transferring high amperages and what are its weak aspects?
A straight comparison of, say, a Goertz foil ribbon and ICONOCLAST cables would be very interesting.
@rower30

Seriously, isn’t this a simple matter? I’m waiting for a mathematical explanation - me, personally, I have no clue how to approach this with other than common sense.
Well, common sense has carried me far enough to demand an answer to things like this. This is seriously bugging my brain!

Since I use integrated units on both my systems only speaker cables are relevant for me. In 6 years, for runs < 2m, I switched from legacy 1.5mm2 generic copper cable to 2.5mm2, and finally to 4mm2 (which was also used when I set up my desktop system). At no time did I perceive any change in sound quality. The ‘upgrades’ were purely cosmetic, since I like the look of chunky cables!

There is no confusion at all. Thin foils are designed to represent low inductance with decreased loop area, and ignore capactance, doing it. Just look at the data. The design is suitable for systems that can tolerate higher capacitance. Loop are is loop area, don’t get confused, the physics doesn’t.

The frequency dependant nature of the foil is the same as a round wire. Make it thicker, and the frequency high enough and the current moves to the surface as the self inductance of the “wire” increases in the center on out. The center of the wire looks higher and higher in impedance to to higher and higher frequencies.

This ignore proximity effect in high current cables (speaker cables) where the magnetic fields either push apart (same direction of current in two close wires) or pull together (opposite current direction in two close wires) the current dennsity. This alters the wire efficiency as the cross section is not used unifoirmly.

Audio is pretty deep skin penetration even at 20 kHz, about 18-mil. The current is only 37% what it is on the surface of the wire with the definition of “one” skin depth. Go two full skin depths and it is 37% less that where it left off from the first skin depth, or 0.37 *0.37 and so fourth.

A wide thick foil exhibits skin depth same as any wire, until you get to the ends where the sharp corners are a real EM field problem as they are decidedly different orientation than the fields along the width of the flat wire, making EM field management and cancellation technology far harder.

Flat wire reach good “L” by SPACING, and NOT secondary field cancellation. Same as round wires closer and closer together. It is just easier to use EM field cancellation in a symmetrical EM field around a round wire.

Just go look at the EM field line illuistrations on various shapes.

Most of audio is diffusion coupled, essentially the same current through the wire cross section, and this is what causes the non-linear issues with frequency. Add that to a non-linear Vp at frequency through audio and we have a pretty poor communication line compared to DC or RF.

The Vp at DC is ZEREO by definition. As we go down in frequency Xc goes way, way up. Xc is capacitive reactance and it simply describes the ability of a capacitor to easily move an AC signal at a specific frequency. Capacitors have a harder time of it at lower frequencies. This is why so much attention is paid to low frequency capacitors (audio is all really pretty low frequency) and how they work.

You would think as frequency rises and Xc decreases, that a wire would be more efficient with rising frequency but, internal inductance goes up with frequency (the opposite direction again!) and kind of trashes that idea.

Cable parameters have several things that go counter to one another and have to be weighed. What do I want more of, less of, the same balance of? How do I even DO what I want to do? Calculating it is one thing, but getting a cable to do it is vastly different. Math won’t tell you, past simpler symmetrical geometric designs, what is going to happen. The EM geometry to balance strand R, L, C, Vp, skin effect, proximity effect and bulk DCR to name a few is a hidden variable you need to ferret out yourself.

A foil has no magic to move current, it needs DCR and CMA same as any shape wire. Make it thinner just means it has to be wider to reach the same total CMA area for the current drawn (same voltage drop across the cable verses a load).

We all think in isolation on cable parameters when they work all at once. We decide today it is one thing and tomorrow another thing. You can’t do that. Cable is a system of attributes that push and pull every other one in a given design. I just chose to try to better balance ALL attributes and understand how they inter-relate to one another. This is all real stuff.

The harder issue is in a “network” between an amp and a load, how much CHANGE can we hear? This should ALWAYS BE the debate as cable measurements SHOULD BE made and designed in properly. It can’t sound better if it can’t measure and calculate better.

There is no sense in doing testing when the starting point of two cables isn’t even known to be accurate and correct. Once we know the cable is better, we can see if it is applicable in use. No two amp/speaker networks are the same. Amps linearity varies into reactance and speakers are natoriously non-linearly reactive. Add the cable for some more reactance.

ICONOCLAST simply uses the accepted physics to make better, although far harder and more expensive, cable designs to evaluate. We explain what and why we did what we did. We measure each assembly so you know it was done. Does it help? At least you know the starting point is really different, and correctly specified.

Any one variable by itself look too little to matter. Without listening, I agree.

Best,
Galen Gareis