Why are we going 300 or more directions?


Funny, if you design a hi-speed coaxial cable, the fundamental design is the same. I do mean the same. Physics have honed the basic construct to the same physical design no matter who makes it.

Yes, conductor and shield materials will change some based on the frequency range, but not the design. If you change the basic design, you get worse performance, and not just differentiation (unless worse is your differentiation).

Then we have audio cables. True, audio exist in a frequency range where stuff does change with respect to frequency (impedance drops markedly as frequency is swept from 20 to 20 kHz) but this still doesn't allow willy-nilly designs from A to Z to hold the best electrical ideal.

If there are X number of speaker cable makers, only a small few can be the most ideally right according to physics for audio transmission. What we have is so much differentiation that it is almost humorous.

If "we", as in speaker cable designers, all got in a big room with the door locked and could not be let out till we balanced the design to best effect...what would that cable look like? Why?

Go to any web site and you can't get one-third of the way through before vendors allow misconception to be believed (references to velocity of propagation for instance) that are meaningless in their feint of hand or simply unprovable as to their effect...simply fear you don't have it. For instance, high velocity of propagation allows you to simply lower capacitance, the speed is there, but irrelevant at audio and cable lengths that you use. The signal travels too fast to matter. Signal delay is in the 16ns range in ten feet. Yes, that's 16 trillionths of a second. It's the capacitance folks, not the velocity that you engineer to. But velocity "sounds" exciting.

Audio cable over the years should be under CONSOLIDATION of principals and getting MORE like one another, not less so. I don't see a glimmer of this at all.

The laws of physics say there is a most correct way to move a electrical signal, like it or not. Electrical and magnetic fields have no marketing departments, they just want to move from A to B with as little energy lost as possible. You have to reach a best balance of variables. Yes, audio is a balance as it is in an electromagnetic transition region I mentioned earlier, but it STILL adheres to fundamental principals that can be weighed in importance and designed around.

A good cable does not need "trust me" engineering. An no, the same R, L and C in two cables don't make them the same. We all know it isn't that simple. BUT, the attributes (skin effect and phase responses) that DO make those same R, L and C cables different aren't magic, either.

I've listened to MANY cables this past six months, and it no longer amazes me which ones sound the best. I look at the several tenets that shape the sound and the designs that do this the most faithfully always come out on top.

DESIGN is first. Management of R, L, C, Skin effect and phase. Anyone cam stuff expensive material in a cable, few can DESIGN the right electrical relationships inside the cable. Why be stuck with excessive capacitance (over 50 pF/foot) to get low inductance (less than 0.100 uH/foot) when it's NOT required, for instance. A good design can give you BOTH!

MATERIALS are a distant second to sound quality. They contribute maybe 2 tenths of the total sonic equation in a quality design and ZERO in a bad design. A good design with standard tough pitch copper will exceed a bad design with single crystal cryogenic OFC silver-plated copper. You can't fake good cable design and the physics say so. Anyone can buy materials, so few can do design.

Being different to be different isn't a positive attribute in audio cables. Except for all but ONE ideal design it’s just a mistake.

I've listened to the same cables with dynamic speakers and electrostatic speakers, and the SAME cables always come through with the same characteristics. Good stays good. True, the magnitude of character is different, but the order hasn't moved.

I'm not real proud of the cable industry in general. True transmission accomplishments should reach common ground on explainable principals and that SHOULD drive DESIGN to a better ideal. But, we people do have emotions and marketing.

What do I look for in a speaker cable?

1.0 Low capacitance. Less than 50 Pf / foot to avoid amplifier issues and phase response from first order filter effects where the phase is changing well before the high-end is attenuated. The voltage rise time issue isn't the main reason low capacitance is nice, it's that low capacitance removes the phase shift to inaudible frequencies and doesn't kill amplifiers.

2.0 Low inductance as we are moving lots of CURRENT to speakers. Less than 0.1UH /foot is what you want to see. Good designs can do low cap and low inductance, both.

3.0 Low resistance to avoid the speaker cables influencing the speakers response. The cable becomes part of the crossover network if the resistance is too high. For ten-foot runs, look for 14 AWG to maybe 10 AWG. Bigger isn't better as it makes skin depth management issue too hard to well, manage.

4.0 Audio has a skin depth of 18-mils. This is where the current in the wire center is 37% of that on the surface. The current gradients can be vastly improved with smaller wire (current closer to the same everywhere). How small? My general rule is about a 24 AWG wire as this drop the current gradient differential across the audio spectrum to a value much less than 37%. Yes, that's several wires. Don't go overboard, though. Too much wire is a capacitance nightmare. Get the resistance job done then STOP at that wire count.

5.0 Conductor management. Yes, point four above says more than one wire, many more! And, if you use 24 AWG wire for skin depth management, it can be SOLID to avoid long term oxidation issues. I've taken apart some old wires and it can look pretty bad inside! Each wire needs it's own insulation.

6.0 Symmetrical design. Both legs are identical in physical designs allows much easier management of electricals.

7.0 Proper B and E field management is indirectly taken care of by inductance and capacitance values. The physics say you did it, or you didn't. BUT, you can design in passive RF cancellation if you use a good design, too. Low inductance says that emissions will be low, however, as less of the energy is generating an electric and magnetic field around the wire, thus limiting EMI / RFI emissions.

8.0 Copper quality is finally on the list. It doesn't matter without one to seven! The smaller the wires (infinitely small), the LESS the silver plate will warp the sonics. If the current density is the SAME at all frequencies, then all frequencies see the same benefit. If a wire is infinitely big than the high frequencies will see the majority of the benefit. 20 Hz and 20kHz are at the same current density on the wire surface. But, the gradient difference is too small to matter with 24 AWG wires. If you want silver, let the silver benefit everywhere!

9.0 Dielectrics. Dead last. Why? Because capacitance is driven by your dielectric. If you have the low cap, you have the right dielectric for the design. You HEAR the capacitance and NOT the dielectric per say. True, Teflon allows a lower capacitance for the same distance between wires, thus making lower capacitance. But, if you FOAM HDPE from 2.25 down to 2.1 dielectric constant, it can meet the same cap at the same wall and sound just as good. Careful though, it is now more fragile! It's a trade-off in durability, not sound quality. Teflon isn’t magic. It is expensive.

10.0 This is not last per say as it is CHOICE in design. I do not like fragile cables laying on the floor to be stepped on. Some do. A good cable design should be durable enough to take that late night trip to the TV set with the light low, and then step on your cable by accident. The cable should be user friendly.

Everything above can be calculated by known physics equations with the exception of copper quality on sound. I'll have to hear this on two IDENTICAL cables except wire quality. But, why would a vendor allow you to do that when they can scare you into a more expensive copper? I'll be glad to pony-up if I'm allowed to make the judgement for myself. Or, let be buy it at a reasonable price!
rower30
These are my general observations from the physics of how all this works. I like repeatable conclusion backed by calculation as that's what physics is, the real world reduced to numbers (with some guesswork even in those!). But, It's at least a common ground for advancement. I just have a hard time with guessing about stuff. I’m open to repeatable, measurable calculations. Since cables are complex superposition of materials and relationships, with each selected or calculated on its own, the final sonic results that are derived are somewhat a black art, no argument there.

Gregm - The skin depth is one of those, when do you stop, arguments. The smaller the wire, the more consistent the current in that wire at all frequencies. It can, in theory, never be the same except at DC. But, lets get real, it can get darn near the same (can't hear it anymore) with numerous small wires. practical reasons usually mean 23-24 AWG as it gets terribly hard to manage more wire than that and not destroy the capacitance or inductance balance. All those wires are trying to hurt the design EXCEPT for skin depth. This is a somewhat an evil business. Every variable is a cancer to the other! A speaker cable is a balance of many attributes, but the overall balance should fall into an optimal compromise. No, they all won't be the same. If you change any one element, the overall relationships all have to move. The physical relationships of the wire and materials result in the blended finished electricals. The compromises made are EVIDENT and KNOWN by the designer, though. This isn't guessing.

So the optimal gauge is going to be at LEAST no bigger than the radius of the wire at the highest frequency of interest. 20 K is about 18-mils. This is just the definition of skin depth, though (37% current differential at that frequency). How small (reduce the current differential even more) you go is going to be locked in by DCR requirement that will rise as you try to optimize one attribute, (forced to use more small wires!) and how far you think your ears can perceive the skin depth issues. Don't rob Peter too much to pay Paul! BALANCE is the key for an overall nice cable. Nothing I have posted here is a secret other than physics we don't understand to put into numbers. But, we have plenty we do understand that can leverage to make better, more logical, cables.

Audiolabyrinth - Buy the sound, yes, not the price. OK, they might be expensive, they might not be. It all depends on what that "differentiation" cost you! Be careful to avoid "trust me" engineering as what you hear, is more than likely the true basics being correct and not the snake oil applied after the fact. Nothing wrong with snake oil, I suppose, as long as the fundamentals are correct. But, many a cable is JUST snake oil and expensive…and sound poorly.

I look at good sounding cables this way, if you have even 10K in a system a $2,500.00 cable that really sounds good to you is about as cheap an upgrade as you get in audio now-a-days. Yes, it's expensive, but can you beat the sound improvements for the price paid? Here is the BUT part, LISTEN to the cables and try to ignore the price and "packaging / marketing". If the fundamentals are there, the cable should sound pretty nice, as the real world physics will allow it to. You can't cheat Mother Nature. The same relationships are in EVERY cable.

03-17-13: Gregm
Rower30: your original post & further "articles" are very interesting and, if i may say so, a significant contribution to the community.
I'll second that. Your writeups make a great many excellent and important points. Well done!

The one area I would question, though, at least with respect to situations where the wire is not plated, is your emphasis on the importance of minimizing skin effect.
Audio has a skin depth of 18-mils. This is where the current in the wire center is 37% of that on the surface. The current gradients can be vastly improved with smaller wire (current closer to the same everywhere).
First, I would rephrase the second sentence to say that "this is where the current in the wire center is 37% of the TOTAL current, the other 63% flowing in the part of the wire's cross-section that is between the surface and the skin depth."

As you undoubtedly realize, with respect to sub-RF frequencies what skin effect basically does is to increase the resistance of the cable as frequency increases. It can be calculated that under typical circumstances (e.g., cable lengths on the order of 10 feet or so, and used with dynamic speakers, which generally have impedances that are high in the upper treble region and above), the effects of that resistance rise will be a rolloff at 20 kHz of a very small fraction of 1 db. That is likely to be completely swamped by room effects, speaker inaccuracies, inaccuracies elsewhere in the system, and the high frequency rolloff and finite resolution of the listener's hearing.

I can provide such a calculation, if desired.

On the other hand, in the less common situation where the length of the speaker cables is particularly long AND the impedance of the speakers descends to very low values (e.g. 1 ohm) at 20 kHz, as it does in the case of many electrostatics, I would agree that skin effect might conceivably become a marginally perceptible factor. And as you indicated, additional considerations come into play in the case of plated wire.

Also, a minor correction to a statement in your initial post, which was most likely just an oversight. 16 ns is 16 billionths of a second, not trillionths.

Again, though, my compliments on what IMO are a great many excellent and important points that are made in your writeups.

Regards,
-- Al
Rower30 wrote,

"No, didn't forget directionality it at all, it doesn't matter."

Are we supposed to throw out all the reports that fuses are directional, that interconnects are directional? Do you honestly think cable companies are preying on gullible audiophiles by marking directional arrows on their cables and fuses? Shall we report all the aftermarket fuse companies - Synergistic Research, HIFI Tuning, Audio Magic, Isoclean, etc. - to the Better Business Bureau? Hell, even cheap stock fuses in speakers and amps are directional - it's not a high end audio phenomenon - it's a physics phenomenon. The high end has known about wire directionality for at least 10 years ; isn't it about time for everyone else to catch up? Are their really ANY high end cable companies who do NOT acknowledge wire and cables are directional? Maybe if we ignore wire directionality it'll just go away.

"When you control the mail you control information." - Newman

"It's what I choose to believe." - Dr. Elizabeth Shaw in Prometheus
...The high end has known about wire directionality for at least 10 years; isn't it about time for everyone else to catch up? ...

In my opinion, no it isn't. There isn't any proof to catch-up to. Is the "audio" community the only place where sinusoidal information is transmitted? Why has no other scientific discipline, with far more fragile signals than audio noticed this phenomenon (well, it would be a phenomena if there was any true evidence it existed) and hasn't taken advantage of it?

Yep, we can take a picture of copper grains in drawn wire and say, see...the grains say to go THAT way! We can add dielectric polarization and batteries to also say we go THAT way. Until, Kickoffs current rule and polarization principals say no, we go BOTH ways and the circuit can't work. Sorry, but a picture isn't a sound. It isn't a proof, it's just the grain structure of copper, nothing more. It has to be directly applied to a signal attribute.

Alternating signals aren't "directional" they are BOTH directions. Which "direction" or polarity is it that you refer to? When there is a single shred of ANY evidence that can be put to the physical, let me see it. Don't tell me it's too complex to explain. EACH individual attribute needs to stand, with evidence, on it's own. This is how the math works. Everything can be taken apart to its constituent components. Nature is built in steps. Sometime a step is hinged. Capacitance and inductance are tied together. Magnetic fields and electric fields are tied together. One creates the other at the same instant. So they have to be looked at as a step in two directions.

Yes, the superposition of all the individual elements can be unpredictable in sound, but each one is readily analyzed on it's own. There is no, "we believe" (maybe because we paid for it?) in my world.

"When you control the mail you control information." - Newman

Ya, that's cute. Who's controlling what? I put fourth my opinion (it is mine) and we try to shut it down with the hi-end audio community acceptance of totally unproven electrical phenomena? The use of the words "hi-end audio" is interesting as it remains complete as anyone not believing it (it can't be proven) is thrown out of the fold so the community remains 100% right? Ummm,I'm pretty hi-end, and no, I don't "believe" it. Not only that, I have never heard it to accept that a proof exists to explain it.

Things like this are generally let alone as it doesn't hurt anyone except their pocket book. The FDA could care less about drugs that are placebo's if you want to buy them. You can change your oil every mile if you want to. But to try to pretend something is real based on blind faith and tell me ignoring it won't make it go away like it existed with any proof in the first place? No, I'm more scientific than that. I don't buy funny pills, I change my oil on proven service intervals, and make sure the cable I buy follow very real design principles. And, I'm sure glad the brilliant minds exist that do indeed continue to PROVE the physical world in repeatable ways. Just believe it? Are we living in the dark ages?

My viewpoint doesn't exclude those that want to address their superstitions (many are bullied into "believing" as those on this very site ridicule them to do so). I use the term superstition as simply that, a belief that an outcome is expected without ant real proof, not as a put-down.

Me, I'm pretty thick skinned and failing to "believe" isn't one of the things that keep me up at night. You better be glad those that design the equipment that we use everyday don't believe faith, as you can't trick the science in those circuits. Mark your cables, add batteries, do what ever, but DO NOT ignore what is proven and pay for those that attributes that are faith based until every real facet of design is well accounted for.

With modern DSP electronics, you could indeed pass a white noise (equal amplitude at all frequencies) through a know system and do a balanced circuit remainder function to "pull-out" the difference signature of various cables. This would be magnitude only. Phase is a more challenging measurement. You can sweep a cable for phase with respect to frequency and probably do a similar analysis. As different as cable do sound good equipment should be able to quantify some, not all, of what we hear.

Count me in when we try to prove what we all can really hear. Have you ever cut your 10K cable in two and pulled all the conductors out of and inch of your cable, and had the grain structure analyzed? We're they really in the same draw direction? OK, the box said they were.

With so called single grain copper it should not be an issue as the copper grain boundaries are gone, and the grains lay parallel throughout the wire till the ends are reached (limited length based on AWG size). You can pay a lot of money to guarantee you're right about directionality by theoretically avoiding it? Well, that's a way to handle it. Just do it in a good DESIGN.

"Maybe if we ignore wire directionality it'll just go away"

Well, what if I ignore something that doesn't exist verses something that does, will it appear? Maybe I'm on your side after all.

I will be VERY careful to not ignore R, L and C while playing my stereo, though, as the consequences could be catastrophic if they go away.

Better yet, see how many cables you can find that adhere to good design practices (ya, even the ones that add snake oil over a good design). The physics say that the proper management of the alternating signal will yield a nice sounding cable. Make a list to go shopping by. Buy more of the real deal in design.