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
With all due respect, while I concede that wires tend to be a consideration in building a system, I would prefer that they just did their job and got out of the way. IMHO, there are better, more efficient ways to "tweak".
Mapman,

For impedance matching in speaker wires to make any difference at all, a few things need to happen.

First, the speaker impedance has to vary enough in the midband frequency range such that a mismatch can cause enough delay variation. If the impedance variation is not large, then playing with the speaker cables isn't going to matter much.

Second, the speakers need to be of sufficient quality that a clear and concise imaging effect occurs. Since the delays will really only affect imaging, if there is no imaging to speak of there will be nothing to "look" at.

Third, the program content has to be sufficiently rich in imaging content that central images are sufficiently stable that you are able to resolve any changes in off-axis image locations with respect to the stable central image. If the program content is insufficient for this, ya ain't gonna discern nuttin.

Fourth, if the program content images are derived by the normal pan pot back at the mixdown in the studio, then the IID parametrics are geared towards the studio monitors, not necessarily a good fit to any system in the field. Add that to a lack of ITD content, and then the user is hogtied into attempting to interpret images based on localization parametrics which have little to do with your system, setup, or your hearing capabilities.

Honestly, that's why I just listen to music for the talents of the musicians...

IC's are an entirely different ball of wax. IC's (especially single ended) and powercords conspire to create ground loops which compromise systems no end. It doesn't help that the engineering community has yet to establish test standards for equipment loop sensitivity, both as a victim and as an agressor. In general, the audio community pays little attention to EMC considerations. In the future, that will happen. But until that does, users can only swap IC's and PC's willy nilly to try to compensate for design flaws in components.

jn
The debate about R, C, L and even metal purity, conductor diameter, dielectric material, all the usual suspects, gets a little moot when you consider how superior cables are after they have been broken in, especially if they have been broken in on an AudioDharma Cable Cooker or similar device AND after they have been cryogenically treated. Then you have to ask yourself, does a treated mid price cable sound better than an untreated high priced cable? Lance Armstrong would not have been competitive unless he had used performance enhancing drugs (since everyone else was using them).
What we were taught in school about t-lines and reflections did indeed discount the possibility of reflections in the audio band for short cables. Unfortunately, that was based on an approximation, one used to simplify the engineer's job. Like the skin effect approximation of the exponential equation, where the depth calculation is good enough as long as you remain within the limits where the approximation is accurate enough. T-lines are the same.

The actual effect short line reflections will have on 1Khz signals for example, is extremely small. 5, 10, even 20 uSec delays on a 1Khz sine is so small that it is ignored in standard work. If I were running a few kilowatts at 1Khz into some load and worrying about delays and losses, I would also ignore ten uSec as well.

Unfortunately, humans have this absurdly powerful capability to discern direction of a sound source at the 1.5 uSec and up level. This level of interchannel time discernment is where the standard engineering techniques begin to fall apart.

The complexity of virtual image localization is sufficiently high, that I always recommend any technical person who wished to consider or argue cables first learn a bit about what humans can hear, as that is really the end result wished..what is audible.

For a low impedance amp feeding a 150 ohm speaker wire to a pure resistive load, the actual current delay at the load will be a function of the line to load match. If load = line, the delay will be exactly the propagation delay, measured in nanoseconds. If the load is very low or very high with respect to the line, it will take a large number of reflections and transits until the load current has settled to 90-95% of the expected value.

Since speakers can vary wildly across the audio band, I would recommend trying to get near the center of the range. It's reasonable to run wires at 25 ohms for example, by using perhaps 5 or 6 independently twisted #18 or #20 awg zips. No specific braiding of rancy stuff, just twiste them independently but make sure polarity is correct at each end.

If you try to go at or below 4 or 8 ohms, you will really have a lot of capacitance in the cable makeup. It has to be noted that capacitance is NOT an issue for any amplifier on the planet as long as the load at the far end matches the cable's characteristic impedance.. But if the load impedance climbs up with frequency, then the amplifier will see significant capacitive storage and may oscillate if the unloading occurs below the open loop unity gain point of the amplifier. The use of a zobel at the far end can prevent the unloading which is the problem.. If your amplifier is marginally stable with a low z cable and high z load, a cable made with a built in zobel will indeed be highly directional.

I do not recommend making the cable lower than the load especially if the load is 4 or 8. My recommendation is to make the cable somewhere in the middle of the load impedance min/max.

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

jn
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.