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
Jneutron -How are you calculating impedance at audio to such low levels? The impedance rises rapidly at audio frequencies and is tremendously non linear. A cable can very easily be 600-ohms at 100 Hz, and drop to 50-ohms at 20 Khz with the open short method.

In don't see any liberties being taken to reduce an engineer's work load when it isn't even working as a transmission line. Oh it's "transmitting" all right, but not voltage.

As short as these cables are, open - short method is used to derive "impedance" even though there is no real impedance as the cable are far too short to manage such LONG audio wavelength. To be a factor, the cable length has to be at least 10X or more the quarter wave length of the frequency of interest. This relates to the fact that a voltage change has to happen BEFORE it gets to the end of the cable and audio speaker cables transit times are too fast for this to happen.

There is NOT true impedance matching reflections in audio cables caused by reactive impedance values verses resistive. The back EMF from your amplifier is many times more severe than so called "reflections" of a hi-current signal in a speaker cable. True, no cable has a 100% transfer to the load (pure resistor), but I think it is somewhat a mistatement to convey it's an "impedance" as it falls well outside what is known under a transmission line situation.

Speaker cable deal in current / power transfer where transmission lines deal in just voltage transfer. With POWER transfer you want the LOAD to be a MUCH HIGHER resistance than the amplifier output or cable so the "power" is dropped in the speaker and not on the amp outputs or the cable. You want the cable to be a pure resistor, too, just NOT a very big one.

So let's say you arrive at your "complex" impedance by adding the vector sum of the real and imaginary (capacitance and inductance) parts. That would be HUGELY capacitive to get to an 8-ohms value with such low real component resistance and inductance. Most of the magnitude is a CAPACITOR! Why on earth would you want to load the circuit with all that capacitance when POWER or VOLTAGE is NOT dropped across imaginary values but only the resistive one? Capacitors and Inductors store voltage and current, only to release it later on (minus their internal resistance, anyway). Add a bunch of imaginary capacitive component to your speaker leads and you create a messy situation even at RF. Talk about phase shift and imaging issues, there is no transfer of energy, just storage and release of energy at in opportune times. It doesn't sit around forever. The higher the capacitance, the worse it gets. We aren't storing nuts for the winter, we want to eat them as the come down the line.

Power is current squared time resistance, and I sure don't want as much POWER dropped on my cable as the speaker (same "impedance")! Of course this doesn't happen since the cable is NOT high resistance so POWER can not be dropped on the speaker cable. But, highly capacitive leads DO NOT aid the transfer of power to the load, either. I also don't want much dropped inside the amps output stage (usually less than 0.05-OHMS). I see nothing here that says you would want to, or can, match a cable to a speaker.

The skin effect calculation is "wrong"? Well, All I see is you have a different opinion right now. Multiple credible sites use the most common methods and all arrive at about 18-mils at 20 KHz. Where is your documentation on your method? I agree that "approximations" can boil stuff down too far. Saying so is one thing, showing us is another. We're all tired of sayings.

For delay, Velocity of Propogation is one over the square root of the dielectric constant. All good dielectrics are stable from 1 KHz to well into the GHz range, Teflon changes less than +/- 0.05 and is 2.15 nominal from 1KHz to 10 Gig and more. The delay is JUST the effects from the dielectric material group delay (some have more than ONE dielectric), and nothing more. It is design agnostic, zip cords or otherwise. You can measure the delay at 20 Hz, but it isn't going to make a huge difference in the arrival time at the end of a ten foot cable.

I still see the yearning to be like the RF guys. Why?

As for others, where's the beef in your audible beliefs? In God we trust, all else bring data.
Directionality - rice puffs.
Cryogenic copper - rice puffs.

We need to start digging out provable facts and using them, not just "hearing" them, to make better and practically priced audio cables. Are people being taken advantage of? Well, what do YOU think? Information is power. Get some.

I have thick skin so getting some good heads to knock me around is actually fun. Learning is NOT a spectator sport.
jn, thanks for your response.
Seems to me that the moderators delay posts if the poster has any history of by chance negatively effecting sales.
GK, I prefer discussing scientific entities. Your statements are not scientifically supported by any test.

If you wish to claim burn in of wires, please provide scientific evidence of such claims.

If you wish to claim cryogenic alteration of either dielectric or conductors, please provide scientific evidence of such claims.

Anecdotal accounts are of no significance as scientific proof. They are useful as a self serving vehicle, but not as proof.

Long time no speak, Geoff. How have you been, how are you doing? I hope all is well with you.

jn
Jneutron wrote,

"GK, I prefer discussing scientific entities. Your statements are not scientifically supported by any test. If you wish to claim burn in of wires, please provide scientific evidence of such claims."

Sorry, this is not some government lab, it's a forum for the exchange of ideas and experiences, including listening experiences. And my experience is that burn-in of cable is critical to how they sound and that trying to evaluate the sound of any cables without proper burn-in is just plain silly. I wish not to discuss scientific entities, I wish to discuss sound.

"If you wish to claim cryogenic alteration of either dielectric or conductors, please provide scientific evidence of such claims."

I couldn't care less about scientific evidence. Besides, I made no such claim, but apparently you are! Mox nix to me, the only thing I'm interested in is how it sounds. I trust my ears, one thing you apparently don't.

"Anecdotal accounts are of no significance as scientific proof. They are useful as a self serving vehicle, but not as proof."

I never claimed they were scientific proof. This is a hobby. Get over it. There is no scientific proof for many things in this hobby. It sounds like you think we should wait until NASA or AES or some government lab comes out with proof of cryogenics and burn-in of cables in terms of how they affect their sound. I kinds doubt that will ever happen. So are we supposed to sit on our hands?

"People would be much better off if they believed in too much rather than too little." PT Barnum

Yes, it's been a little while, are you are still at the government lab?

Geoff
I have copied your post and am interjecting comments in "" "" marks, it gets less confusing that way. I wish I could color my inserts red, but such is life..

First however, one clarification on a comment you made earlier, that a vacuum dielectric would have no capacitance. Totally wrong. Capacitance is proportional to epsilon free space times epsilon relative. For a vacuum, epsilon relative is 1, and epsilon free space is 8.854 times 10e-12 farads/meter. I DO NOT UNDERSTAND HOW AN ENGINEER COULD MAKE THIS MISTAKE.

How are you calculating impedance at audio to such low levels?

""As I've stated prior, hf impedance is 1/sqr(L/C) At lower frequencies inductive reactance is very small, and the conductor resistivity starts raising the impedance. The full form is of the style "(R +L)/(C+G)". Unfortunately there is no equation editor on this site..sorry.""

The impedance rises rapidly at audio frequencies and is tremendously non linear. A cable can very easily be 600-ohms at 100 Hz, and drop to 50-ohms at 20 Khz with the open short method.

""I've stated that as well If you wish a general feel, the Belden website illustrates this for a general 75 ohm cable. For audio use, I recommend a value 2 to 6 times the hf value""

In don't see any liberties being taken to reduce an engineer's work load when it isn't even working as a transmission line. Oh it's "transmitting" all right, but not voltage.

""Do yourself a favor. Get an HP 8721A reflection bridge and look at the reflections which occur in the audio bandwidth. You will learn something new.""

As short as these cables are, open - short method is used to derive "impedance" even though there is no real impedance as the cable are far too short to manage such LONG audio wavelength. To be a factor, the cable length has to be at least 10X or more the quarter wave length of the frequency of interest. This relates to the fact that a voltage change has to happen BEFORE it gets to the end of the cable and audio speaker cables transit times are too fast for this to happen.

"" you are repeating generalizations and approximations which were simplified for engineering use. This discussion is beyond that. You need to ask more questions and make fewer incorrect generalizations.""

I'll jump to one other erroneous statement of yours for brevity. You've provided quite a bit of erroneous statements, but I believe everybody's time is better served by you asking questions on this topic. I am happy to teach you if you wish.""

The skin effect calculation is "wrong"? Well, All I see is you have a different opinion right now. Multiple credible sites use the most common methods and all arrive at about 18-mils at 20 KHz. Where is your documentation on your method? I agree that "approximations" can boil stuff down too far. Saying so is one thing, showing us is another. We're all tired of sayings.

Documentation?? On Bessels?? Really?

Do yourself a favor, google Bessel functions, google skin effect approximation, look it up in a good E/M textbook, something. I gave you an exact engineering statement on how time varying rate of change Lenz effect current exclusion occurs within a cylindrical conductor, and you come back with that???

You need better sites. Just because it's on the internet doesn't mean it is correct.

Please pay attention: The exponential equation is the solution for an E/M PLANAR WAVE driving into a conductive surface NORMAL to the boundary. It is NOT THE EQUATION FOR CURRENT REDISTRIBUTION IN A CYLINDRICAL CONDUCTOR WHERE THE CURRENT IS AXIAL. Skin effect in a cylindrical conductor is a consequence of Faraday's law of induction within the conductive material due to the internal magnetic field caused by the axial current. The exponential equation is an APPROXIMATION EQUATION used so that engineers do not have to get mired into the bessels. ""

I still see the yearning to be like the RF guys. Why?

""If this question is intended for me, you are barking up the wrong tree. What I speak of here is a very small subset of what I do for a living.""

I have thick skin so getting some good heads to knock me around is actually fun. Learning is NOT a spectator sport.

""It is good you have a thick skin, you are going to need it. You are not in Kansas anymore, Toto.. (no offense intended, I just HAD to use that statement..)""

I have been told you are an engineer. What I have seen posted by you is a mixed bag of engineering facts, incorrect statements, typical internet factoids. Are you an engineer, and if so, what kind?

Me, I am an electrical engineer. I design, build, and test superconducting magnets for particle accelerators, medical synchrotrons, antimatter confinement bottles, and MRI's....in addition to my other responsibilities which are more esoteric.

I appreciate and share your desire to maintain some semblence of scientific reasoning in all this. I just have a rather more advanced understanding of the problem, and find it is always necessary to teach others what they need to know. Your need to learn this is by no means unique in this regard. As I stated initially, "we" are going in 300 or more directions because so many people, you included, continue to promote somewhat erroneous engineering and physics concepts. Promotion of erroneous beliefs is part of the problem, not part of the solution.

jn