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
It seems that this thread is going 300 or more directions!,thanks, jneutron,, regarless of the science here with audio cables,as I said,as an audiophile I buy what my ears tell me that sounds good!,LOL,this thread reminds me of a comedy on t.v. called the big bang theory!
Jneutron

...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....

Good, this is correct. Sometimes my head is in a vacuum...sometime not. That number is much higher than I would have expected, too.

...""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""..

I'd rather know what they are at audio, but they are of little use in a speaker cable circuit load which do not act like true transmission lines in the manner we use them. On one hand we want precision, and the other we don’t, it seems. I do agree this can get really hard to characterize, and sooner or later it is indeed precise enough.

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

Yes, the methods commonly used are correct, and verified in three places. But, you feel at lower frequencies, like impedance, differing assumptions are made. So there may be different methods, but the object is to determine exactly why, and to what degree the various methods are limiting performance. If the equations overlap, and there is no ideal wire small enough to be "perfect", than knowing approximately where to be on wire size is OK. Since we can’t make a perfect skin effect wire, at what point is one “good enough”? You comments, please.

""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.""

Nope, I need not speak of people, I speak of principals only...so I did not intend the statement to be derogatory to anyone so much as getting the right information. Some feel God like in their presentations, some don't. Your posts aren't really about information they seem to be about you. I’ve said this before, the “push” (fill in your awesome ness) then “tell” (your story or throw your arrows) is not a sign of maturity or constructive advancement of the subject matter. I’m here for the subject matter and advancing the understanding for all involved. I haven’t figure out your purpose yet.

...Be nice, get nice. Be arrogant, get same...

Yes, I agree with that. But, I think some of this deservedly stuck to me with a little bouncing off me and sticking to you. True class keeps its class at all times. Yea, it's tough, I know. We do our best. Me, I'm fine with good information, being corrected and moving on. I don't use my knowledge to go hunting for those that don't without any real regards for the actual topic, just the hunt. Grow some civility with your posts and more will follow. You seem to be aware of this, so why not change it? Witness...

“…ps. are all posts on this site moderator approved, or is this a trial period for bad eggs like me?…

No, we love having you. What you say is good enough. We’ll make good use of your input and being respected for that should be a better feather in your cap than simply using the push tell prose (you guys stop me when I do it to…yes, you too Mapman!)to mash people.

OK, enough of that lets do something.

Your comment here Jneutron, …cable impedance changes at all frequencies based on the amount of real to imaginary components in the complex impedance. The RF return loss will vary significantly with each frequency point. The higher the imaginary component, the higher the reflection signal and the worse the signal transfer to the resistive load. The cable can be 75-ohms at all frequencies even (not likely!), but have differing reflection coefficients. Throw that into a speaker resistive load, and it gets messy for sure. Low frequency signal is a whole different world.

As low as the resistance is in 10 AWG speaker cable, arriving at an eight ohm load requires a good amount of "something" imaginary (most cables end up most capacitive) to create a complex impedance that high relative to the cable's very low resistive component. I don't see realistically consistently matching the speaker cable to the load by adding capacitance. True, some cable can be made to a specific length to “add” capacitance. Has anyone played with this? Not that it would be easy to do (cut up expensive cables) and or buy various lengths of cable).

With such LONG wavelengths, it seems odd to suggest reflections are from true wavelength load reflections. Yes, I hear you on measuring the reflections, but the load has to be taken into account, too. RF uses a resistor equal to the characteristic impedance. I’m still not convinced of how reflections allows us to convey this as a transmission line.

For power transfer, the speakers get mighty hot, the cables not so much. I’m not clear on exactly where you suggest all the energy is dissipated any why. Resistors absorb power, and the cable is not a good resistor. Audio is still a pretty slow AC signal not too far removed from DC. We want power on the load.

When the waves begins to approach the length of the cable used it is plausible to consider "reflections" as a transmission line. We aren't really close to that in audio. The cable isn’t alone in all this, the back EMF from the speaker is a hell of a circuit in itself.

When you “freeze” the circuit, it’s a static situation. The current and voltage can be examined in turn. AC voltage signals in a transmission line are “pulsing” in the line so to speak, at each frequency if the ideal transmission line acts like it should. But a speaker cable with LONG wavelengths into a speaker with low output impedance from an amplifier?

Trelja

No, I have one NORDOST cable as a reference. Trust me, it was much better than the alternatives. And, to "end up with" is a certainty no matter what we use, you included. Are you to be a poorer judge of cables if one is deemed better than yours is by someone? Many feel differently about NORDOST speaker cables (I don't have those). But enough on that, you'll have Jneutron on your case in no time. Tough love, but he is knowledgable.


Mapman
"I like Jneutron's statement earlier that it is design that matters, not cost. A good mantra for any decision making process involving technology"

No, that was I, go to the top of the thread..."DESIGN is first...." This was the purpose of the thread, to put design ahead of myth that is paid for.

And, my point was, and still is, to get audio cable out of the closet. Many are simply afraid of conflict, as that seems to be the general direction that "knowledge" tends to be going all of a sudden, and NOT to the real subject matter. WHAT are the major issues with audio cable design that can indeed be characterized by known principals?

I stated what is somewhat relevant, but the issue is to drill that down to a finer level so we can all better examine cable constructions for neutrality and possible performance.

I'd rather have half the knowledge and work towards a solution than all the knowledge and sit there with it. Jneutron, where are "our solutions" as you see them? What attributes do you look for?

This group should use each member’s input to help move the topics forward, not throw arrows or use indefensible arguments that can’t be analyzed when this thread is about just that. Believing is fine, but this is for the other half.


Go here;
http://www.audioholics.com/education/cables/debunking-the-myth-of-speaker-cable-resonance
In reality cables DO NOT resonate at all! The model represented here is single RLC lumped circuit for simplicity and is only accurate at audio frequencies for circuit analysis. A speaker cable is actually a distributed element and should be represented as infinite number of lumped RLC models. As an infinite number of lumped RLC circuits are modeled becoming its true distributed form factor, we see the resonance frequency go to infinity.
In addition, once we approach much higher frequencies such as in the RF region we must re-evaluate the cable as a transmission line. In that respect the characteristic impedance becomes the SQRT (L/C) =SQRT(8.8*10^-6/700*10^-12) = 112 ohms. So if our source and load terminations at transmission line frequencies (1/6th the wavelength) do not match, we see reflections in the line, which can appear like a resonance behavior, but in reality are simply reflections or power loss down the line.

Also note that when an exotic cable vendor claims Inductance, Capacitance and Resistance dramatically varies within the audio band, that this is more total and utter nonsense as can be seen in the following real world measurements...

As always, we welcome any cable vendor to furnish us proof of their claims, and cable samples for us to conduct our own testing for verification purposes. I agree, the FTC should be involved in this business, as it is a consumer product based on engineering truths that must not be ignored. - edited to remove vendors.

END

I don't know you everyone.
We look at 20KHz signal (lower than this is even more far fetched) that are far, far too long to properly conduct as a transmission line, add-in the fact that the load is not matched to the cable, and varies with frequency as does the cable too and you have a line model that is closer to your 110-volt wall outlet than your CATV outlet.

END

http://sound.westhost.com/cable-z.htm
In order to obtain a low characteristic impedance, it is necessary to have very low inductance and relatively high capacitance, and the high capacitance may impose serious constraints on the amplifier. Indeed, many amplifiers will become unstable if there is sufficient capacitance connected directly to the output, causing oscillation which may damage the amplifier. As described above, regardless of anything else, the cable does not act as a true transmission line at audio frequencies, and claims to the contrary are fallacious.

Matched impedances ensure maximum power transfer from source to load, and this is obviously very important for RF transmitters and telephony applications. It is completely irrelevant for a solid state audio power amplifier however, since the drive principle (known as voltage drive, or constant voltage) does not rely on maximum power transfer, but relies instead on the amplifier maintaining a low output impedance with respect to the load.

Even though most power amplifiers are limited to at most a few hundred kHz or so, there can still be some energy at higher frequencies - typically noise. What often happens is that an amp can be quite stable with a capacitive load and no signal, but as soon as it is driven it "excites" the whole system, and it then bursts into sustained oscillation.

At audio frequencies, speaker cables are not transmission lines. They are merely cables, with inductance, capacitance and resistance. Despite popular belief, they are bereft of any magical properties, only physics.

It is worth noting that a cable will never act as a true transmission line with a defined (and maintained) Zo unless its source and load impedances are equal to the line impedance. This means that no audio cable will ever be a transmission line, (almost) regardless of length, unless the amplifier output impedance, cable impedance and load impedance are all equal at all frequencies within the desired range. No known amplifier or loudspeaker system can meet these criteria. Alternatively, the cable may be infinitely long, however this is usually impractical in a domestic environment.

END

The above is pretty much what I've said all along. And will continue to say. Keep capacitance lower is better, and the cable is NOT a transmission line.

I do not agree that wire is wire to the extent that audioholics goes to. Make a cable with two large stranded conductors and one with multiple solid AWG strands of the same AWG (or just a different design) and the differences are definitely there.

I'd would indeed like to visit audioholics with the two types of cable and set-down and measure the cables and have them formulate the impact of the design on the sound through measurements. I haven't seen this done, so you can't deny that it could not be done. This would be tremendously informative.

I'm not going to hide behind "my" hearing and say XYZ exists (transmission-line effects) or any other "invisible" attribute. This is to properly define a good audio cable with realistic attributes everyone can enjoy.

The wealth of evidence is not in the favor of audio as a transmission line.
Some have asked about ZOBEL networks as we've moved along. Here is a good analysis of what they can do for you;
http://sound.westhost.com/cable-z.htm

Granted, we don't have a true transmission line with a speaker cable since output, cable and load impedances aren't ever matched and the line is too short, but as Jneutron pointed out, there are termination reflections based on cable length. A Zobel network can remove them WHEN you know the "impedance" of your speaker cable. The article doesn't state the frequency of the cable impedance calculation, which is varying with frequency pretty badly. The objective is more for amplifier stability than cable "sound" per say. Still, some amps may benefit from Zobel networks. Those that want to try one, here is a good place to start.

You need to use the right quality / type parts, and depending on your amplifier, you could get tertiary benefits. Long cable low cap or short higher cap cables are more likely to see enhanced your amplifiers performance with a speaker end Zobel network.

Jneutron, where should user's of Zobel networks calculate the impedance? What do you use when you suggest cable "impedance"?
Rower30 wrote,

"This group should use each member’s input to help move the topics forward, not throw arrows or use indefensible arguments that can’t be analyzed when this thread is about just that. Believing is fine, but this is for the other half."

Ok, fair enough, but I'm getting a bad feeling this discussion is being limited to those who have trouble trusting their ears and rely on textbooks and Über Measurement Specialists to tell them what they should listen to. I was under the distinct impression advanced audiophiles had jettisoned such old fashioned notions back in the '80s. "Believing is fine." Yeah, right, as if audiophiles are religious heretics. As they say on The Shark Tank, I'm out.

"It's what I choose to believe." Dr. Elizabeth Shaw in the movie, Prometheus