tag
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!
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!
74 responses Add your response
Jneutron, as you probably already know, cryo is used for many metal items like high performance pistons, engine blocks, golf clubs, razor blades, all manner of tools, etc. I used to cryo my brass rods for my sub-Hertz iso platform as well as all the metal fittings, figuring better safe than sorry. One of my fav isolation techniques are what LIGO uses in the search for gravity waves, which (at one time) included single crystal sapphire thread suspensions for optical elements, Multi-stage monsters than employ heavy masses on springs, not to mention active components. Yes, I know what you mean about angst on the job, we used to call it the night of the long knives when the rumors about cuts started circulating. Lol |
Geoff, You've made me laugh now. I've only been considering heat tempering/quenching for antique clock springs, and am preparing to purchase firebrick to be able to cherry red springs about 6 inches dia un-sprung for oil/water quench. Believe it or not, I never considered LN2 post processing. Go figure. I'll have to do more research on the spring materials, as I don't know if they have a martensitic finish temperature, or where it is, or carbon content either (most do rust). The application really frowns on microscopic cracking as that is a typical failure mode, but you've now got me thinking. Still, it's gonna take some research specific to re-working spring steel that's more than a hundred years old. Personally for me, the funding stream is scary stuff. Luckily, the big project I'm working on is through 2016, and the smaller more esoteric ones go past 2020. But hey, the angst never goes away. The vibration stuff I mentioned to you years ago went well, we used all kinds of piezo's, geophones, lasers, and some active tables for measurement and cancellation. It's amazing seeing voices cause measureable vibrations as seen on a scope on a 15 ton granite table. jn |
Jneutron wrote, "Geoff, You mentioned tempered springs. Do you get involved in the tempering at all? I ask because antique clock mainsprings tend to lose their strength over time, and I suspect that I may be able to re-temper them after opening them up again, perhaps oil or maybe water quench. I was wondering if you've had any experience in that." I have about 15 years of experience with cryo labs and used to cryo my springs six or seven years ago when I used larger springs, that were already hot oil tempered; these days my springs come heat tempered. The high carbon steel springs I use now don't loose their strength or stiffness over time. I have cryo'd all sorts of things over the years, most recently my interconnects and power cords plus CDs. "And, you did indeed blow off the question again. I wasn't asking about your work....I was asking about you." I have been doing pretty well, you know, considering the recession and everything. My last real job was in the FAA office of safety doing risk analysis for some big technical programs. Ocassionally i think maybe I'll go back to work but so far I have managed to avoid it. Geoff |
"You've traded off noise and hum protection to gain in capacitance and impedance. " Actually, I did have noise/hum issues from external EM fields with low level phono step up transformer device itself. I put that device (with DNM ICs running from it to phono input) inside a makeshift mu metal container to address that. I have not had need to use my alternate MIT ICs, which are shielded and have that advantage. DNM resons are fantastic all around performers I have found in practice and my preferred ICs. Coherency and detail top to bottom are their best traits. The minimalist design seems to work well and keep things affordable to-boot. Your assessment would seem to be in accordance with what I have observed/heard FWIW. |
Geoff, You mentioned tempered springs. Do you get involved in the tempering at all? I ask because antique clock mainsprings tend to lose their strength over time, and I suspect that I may be able to re-temper them after opening them up again, perhaps oil or maybe water quench. I was wondering if you've had any experience in that. And, you did indeed blow off the question again. I wasn't asking about your work....I was asking about you. John |
Mapman, Yah, they do look like the old style antenna wires... That configuration will increase inductance and lower capacitance. Low C is always liked by the audio guys. This also increases the characteristic impedance of the cables as well. Phono ins are 45K give or take, amp ins run 10k give or take. That style certainly is closer to the load impedance than normal coax (50-75) or twisted pairs (100-150). There are a few ways to skin the cat so to speak. Shielding as per coax protects the higher impedance inputs from stray E fields, that cable doesn't. Twisted pairs is not as good for E field, but is better for magfield protection. Parallel such as that is worst case for both in terms of shielding. You've traded off noise and hum protection to gain in capacitance and impedance. But honestly, if you have no noise or hum issues, that is great..Tain't broken, don't fix it. All IC's can suffer loop induced hum and noise incursion from external magfields, but you seem very happy. Is it a sound design approach? Yes, it certainly is. If you had noise or hum issues, it would not be the best design approach for your system. ps. AS a general rule, if a circuit is lower than 377 ohms impedance, it is sensitive to inductance and time varying magnetic fields. If the circuit is over 377 ohms, it is more sensitive to capacitance and time varying electric fields. It is also important to consider the level of the signals in the circuits as well. Speaker runs will be inductance sensitive to a point, but external magnetic fields can't really compete with 100 or 1000 watts of power. jn |
Jimmy/Rower, can either of you explain to me why the fairly unique minimalist designed DNM Reson analog stereo phono plug ICs that I use and like in so many ways sound as clean coherent and lively as they do? They essentially look like old style 300 ohm antenna wires but use a small gauge single strand wire. The simplicity of the design attracted me initially and I have been very impressed ever since. Do think this is a sound design approach? Thanks. |
Rower, You said: You seem to be a little too easy to get upset about some things so it's going to be hard to please you. I'll do my best. My response: Nothing could be further from the truth. Your statement is a diversionary tactic being used in an attempt to push blame on others rather than admit to your own arrogance. It is a common enough tactic, many people use it. You said: Zero capacitance? Sure, my perfect conductor example was just that. My response: NO, you stated that when the insulation is a vacuum, there is no capacitance. Here, I'll refresh your memory...you said this exact thing on 3/15/2013: 4.0 The dielectric would be a vacuum so we have ZERO capacitance and velocity would be 100%. My response to that was No, a vacuum dielectric does not have zero capacitance. In addition, I provided the free space permittivity number, 8.854 times 10 to the MINUS 12 farads/meter. You then stated : That number is much higher than I would have expected, too. My response... Your kidding, right? I provide a physical constant, free space permittivity, and you say it's higher than you expected??? This physical constant is taught to ALL physicists and engineers, as well as in every AP physics course in high school I've become familiar with. It is needed to calculate capacitance. You've never seen it before, have you. It is also "odd" that someone would thing that the number .000000000008854 is "larger than expected".. This statement of yours is a very clear indication: 3.0 Carries energy in BOTH directions at the exact same time. Umm...this is a short circuit in reality. My response: WHAT???? A SHORT CIRCUIT???? YOU ARE ABSOLUTELY CLUELESS WHEN IT COMES TO TRANSMISSION LINE THEORY, FREE SPACE WAVE PROPAGATION, AND EVEN SIGNALS TRAVELLING THROUGH INDIVIDUAL CONDUCTORS. Pay attention. There are many websites out there which explain transmission lines and signal propagation. Find them and learn from them. You stated: I can't say I grasp speaker cable impedance at such low frequencies as they "rise" as the frequency drops, making consistent low impedances at audio seem implausible, at least to my way of thinking about the measurements. My guess is if you look at the cable like a T-line, the impedance is the same at any cable length. Of course, the low pass nature of the cable changes too. My response: I CAN say I grasp cable impedance. I can say I understand real skin effect. I can say I understand transmission line theory. The reason: I am an EE. I do this for a living. I've done so for 35 years now. And I do it at a level which unfortunately, makes my resume incomprehensible to almost all EE's at the ScB level, most at the masters. I am more than happy to share my understandings on the web so that others may learn. I am not so happy when wannabe "engineers" attempt to use arrogance, belittlement, hobbyist website content, and rambling incoherent prose disguised as "technical speak" to badger others. Your type of "engineering" is one of the primary reasons cables and cable discussions are stuck in a quagmire. I have provided valid reasons why cables can sound different, speakers, IC's, as well as power cords. Not that they all do, but rather, the physics processes which do impact the electrical function at some level. That stated, if you wish to discuss actual technical things and how they can alter sound, fine. I've no problem with that. But you have to drop the shtick, it's old, it's worn, and you can't support the technical arguments. jn |
Jneutron, oops, did not mean to blow off your question, I have been assembling a new headphone system. For insurance I had the ICs and power cords broken in on the latest AudioDharma Cable Cooker and also sent them off to the cryo lab, figuring better safe than sorry. :-). I'm using small 1" tempered steel springs and heavy masses for isolation of modded Oppo 103 and hybrid tube headphone amp. |
Jneutron You seem to be a little too easy to get upset about some things so it's going to be hard to please you. I'll do my best. Zero capacitance? Sure, my perfect conductor example was just that. You can't do anything in that cables example let alone the capacitance. Not sure why you got so excited about it. Yes, a dielectric constant of 1.0 is a give away to the fact that capacitance can't be zero in THIS world, but I wasn't limiting the perfection to the real world but the "perfect" world where things do go infinitely fast, have no resistance, ETC. I see no sense in making a "perfect" wire half-in one world and then the other. So, I put it all in ONE world. And yes, you're right, I do not have a source for very low frequency skin effect. Nor does it seem anyone else! As long as the numbers are "close" and you use a wire size that is smaller than the calculation, and use the number of wire to meet DCR things should get into the reasonable range. As far as transmission line effects well, the source impedance sure is small at less than 0.05-ohms on average of an amplifier's output stage. The cable impedance is small (looking at the real component of the cable) compared to the speaker's varying input impedance so it is hard to imagine the speaker cable as a classic transmission line (matched source, line and load impedance’s). Not to mention the wavelength are WAY long to even begin to couple between the source and the load. A reflection bridge certainly can show reflections but to say this is a transmission line? If I shove my amplifier up to the speaker terminals where is all the power dissipation going? the speaker. If I stick a cable in there, the power is still going almost all into the speaker and not the cable. The L and C energy eventually goes into the load but is lagging one way or the other. Probably not a good thing. True, the "impedance" of the cable can be complex in nature and a higher vector magnitude per low frequency equations (mostly capacitive, as the resistive load value is so small in the cable). But at such a low frequency it's really hard to see this as a transmission line, or impedance values near the speakers input impedance. How do we negate the effects of the LONG wavelengths relative to the line length at audio? Even worse, go lower than 20KHz. I'm all ears on your low frequency transmission line model (pun intended)and impedance matching. The Z=SQRT(L/C) is only good above 1 MHz. The ability to design to metrics that are repeatable would be a great benefit to designers who want to use the best of what's really capable in design without "faith" based engineering. But, I'd rather try to do the right thing with a few bumps in the road than do the wrong thing perfectly. Too little risk can limit the outcome as bad as anything else. Yes, we lose a few that insist on only what they perceive and hear. That's fine, but for right now I want to concentrate on the "knowns" (yes, even the one's I don't know!) to look for in a nice, and reasonable, cable. Design elements that are always beneficial to sound. Bridges go up and fall down, space shuttles go up and explode... all these things have "experts" at the wheel and still failed. People may be experts, but the ones that do their jobs can overreach even their understanding(s). So, as far as being the second one, I sure didn't know I was competing with the first. Sorry about that. If I only stick with what I know today, what benefits do I achieve tomorrow? Looking at cable, you can't see a common design thread across the lot of them that indicates forward thinking to a known set of conditions. I can even see a few, not hundreds, of designs for a specific set of amp (SS or VALVE)/speaker (dynamic or electrostatic) combinations. I listen to cable with the same R, L and C and am amazed at how different they sound. I am not even close to shutting down my ears. That’s what got me in this mess! How do you recognize correctly made audio speaker cables. I did look back at some of your post so as NOT to pester you, and yes, the main things my ears hear is much improved openness, imaging stability, precise location of the image and debth in good speaker cords. I can't say I grasp speaker cable impedance at such low frequencies as they "rise" as the frequency drops, making consistent low impedances at audio seem implausible, at least to my way of thinking about the measurements. My guess is if you look at the cable like a T-line, the impedance is the same at any cable length. Of course, the low pass nature of the cable changes too. With your respone Jneutron, I close comments in this post. I've bugged you all enough. |
Rower, A simple followup. Your first post to me included your words.."""information is power. get some."" You are arrogant without foundation to be so. I provided actual engineering on skin and cables, most taken directly from UNDERGRADUATE engineering E/M texts. You "counter" with non peer reviewed content from audio hobbyist websites. Your technical discussion attempts appear to be cut and pastes from online sources, mainly the same audio hobbyist websites, and how you meld them together tends to be both inconsistent and inaccurate, as though you do not have a real understanding of the topic.. Your attempt at diverting the discussion into one of ego has been seen before. Like this gem... Stated by rower:: 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... end of quote.. How old are you??? Bounce off me stick to you??? Stick to topic and please post more like an adult. Enough of the unpleasantries, perhaps that chapter can be left behind? Your call. 1. Skin effect within a wire is NOT correctly calculated via the exponentional equation in the audio bandwidth. Skin effect is not as pronounced as the exponential equation describes. That is because the exponential equation assumes the energy is an E/M wave impinging on hte conductive material, NOT being generated by internal currents. You clearly have a problem understanding this. Do us all a favor, E-mail the owners of the sources you are quoting from , Rod Elliot the owner of sound.westhost, or Gene Delasalle, owner of Audioholics...give them verbatim everything I've stated on skin effect, ask them if I am correct. Both will either agree with what I've stated, or they will go to their trusted sources to ask what the story is. In which case, I might get some e-mails. I haven't been in contact with Rod in years, last time we discussed techniques for measuring doppler distortion in speakers, maybe 8 years ago... Gene, I discussed some article possibilities a few months ago. 2. Cables as t-lines at audio frequencies. Here, I guarantee both of your audio hobbyist website "sources" WILL have to contact higher level technical resources. There are only two sources on this planet I am aware of that understand this and have MEASURED, modelled, and quantified it cleanly. Cyril Bateman, and myself. (there may be more, I am not aware of them). Cyril wrote a really nice but unfortunatly extremely technical article which goes over the heads of most people. I am using this understanding to better a work project. Repeat, actual hardware. I shudder at making this post so long, but the delays are incomprehensible to me... Rower Quote/question: 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? End of quote. Another slap upside the head. And you wonder why you have problems with someone of higher technical proficiency?? I stated that rather clearly before, go back and read. Human ITD discernment is 1.5 uSec interchannel max. Any effect which is in excess of that threshold cannot be discounted as inaudible. When the line/load mismatch is such that current group delay exceeds that threshold in the mid audio band where our undithered loclaization capability is strongest, method to reduce that delay are required. Rower quote/question:: Jneutron, where should user's of Zobel networks calculate the impedance? What do you use when you suggest cable "impedance"? End of quote.. I already stated that, you either missed it or did not understand it. When a t-line is terminated by a load which matches the line, the amplifier DOES NOT SEE A CAPACITANCE. It sees a resistance. That is INDEPENDENT of the characteristic impedance of the cable. If you run a 5.77 ohm cable with 300 pf per foot and 10 nH per foot, into a 5.77 ohm load, the amplifier sees NO CAPACITANCE. NONE. You need to understand this. When the load becomes higher impedance at higher frequencies, THEN the amplifier will see capacitance. It is a consequence of the line to load mismatch, NOT a consequence of the cable per foot capacitance in isolation. When the load "unloads" at higher frequencies which are BELOW the amplifier's open loop unity gain bandwidth, the phase margin lowers and the system will be marginally or entirely unstable. A zobel is used to load the line at frequencies the speaker will unload at. At audio frequencies, if you wish to know what the amplifier "sees" given the line impedance and the load impedance, just calculate the energy stored in the cable. When line equals load, the inductive and capacitive energy storage will be equal, and it will be a minima. The amplifier will see a resistor. When the line is much higher than the load, inductive energy storage will dominate. When the line is much lower than the load, capacitive energy storage will dominate. And, regardless of the ratio, all energy that is stored in the inductance and capacitance will make it to the load. I know full well where you get this dissipation schtick wit respect to capacitance and inductance, I've seen that site. AND IT"S WRONG. Both storage mechanisms introduce phase lag, not dissipation. My post consists of technical theory and practice within the disciplines of E/M physics, amplifier design, and human localization. You would be better served asking questions on entities you either lack understanding of, or have a different opinion. Using audio hobbyist website content as technical argument material has it's limits. Needless to say, you spouting t-line approximations which were taught for the RF guys is a waste of time. You do understand that it is taught that way so that we can use smith charts, right? Geoff, you crack me up. btw, you never answered my question..how have you been? I hope all is well with you. jn |
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"? |
You cite audioholics as a source??? That explains a lot. Gene D's a nice guy. Some of the articles are pretty straitforward, even though I don't care for the style. I didn't even mind that he quotes some of my technical explanations in some of his articles. On occasion he'll ask me to write a technical article or two for him, but we've not gotten together on that. What I prefer to write is a tad over his target audience with respect to E/M theory, and he would rather have the debunking style. But to use his site to debunk of what I'm discussing is funny. The last person to do that was trying to teach me skin effect from AH, and he was quoting me in an attempt to teach me my quotes....incorrectly btw. Hmm, you appear to be the second one.. You never answered my question. Are you an engineer, or did you learn skin effect on the web? I asked that seriously, because you had no clue as to what I was speaking of with respect to skin effect and Bessels. You still do not know that the exponential equation is based on normal e/m waves at a conductive boundary, and it is inadequate for audio frequencies and audio size wires. Rod Elliot's also a nice guy. But he's still not an E/M guru, nor does he have a good handle on EMC theory. As I said, you need better resources. I mentioned a few, but you could just ask. Do you really believe that websites like that are sources for E/M theory?? As to your belief that cables cannot be transmission lines. Silly and inaccurate. Get a reflection bridge and see for yourself. Cyril Bateman did.. You have a lot to learn. jn |
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. |
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 |
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. |
I'd like to offer my thanks and congratulations on one of the more interesting and entertaining cable threads I can remember. Not since the time of JD (Jade) have I felt as interested in cable. The analysis reminds me a lot of the outstanding AudioQuest advertising copy from the 1980s. After going through all of their arguments, the choice seemed so apparent. It wasn't until I lived with AQ Midnight for a bit did I realize that despite all of the logic, the cable sounded surprisingly mediocre. Along with Carver amplifiers and Legacy speakers, AQ taught me the lesson of the dangers of drinking by the label when it comes to this hobby. In the end, while I appreciate (more than you're going to believe) everything you've laid out, again I'm left disappointed as I read you wound up with Nordost. In my opinion, one of the most amusical and wrong sounding cables I've come across. Ah, high-end audio cabling... |
H Geoff, same employ for me, same games for you I see. It'd be a boring world if you conformed...I don't want a boring world.. Rower..I just knew I'd mess up the quotes...sigh... Audiolab... Much of what Rower has stated is in error or misconstrued, you should not expend energy confronting such content. A general question: Is it possible to bold or italicize in this forum? I'm trying to be clear and not mis-attribute. jn |
Rower,sorry to respond before you have a chance to see my last post.. These two paragraphs tell me everything I need to know about you. "quote" 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. 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. "end of quote" It is quite clear that you have not taken any courses in E/M theory. I would be happy to recommend some texts for you. Don't worry, I won't recommend Jackson nor Becker. Both are far too involved for you (actually, for all humans). I was thinking Rojansky or Shadowitz perhaps. Or ask. As a start, several equations along your path of learning. E = 1/2 L I squared E = 1/2 C V squared Z =sqr(L/C) Using these equations, you should be able to determine the relationship between the energy stored within the cable as a consequence of capacitance, and the energy stored within the cable as a consequence of inductance. You may even note that they are equal when the signal travelling down the wire has the voltage to current relationship which matches the characteristic impedance of the cable. You may or may not understand that the only signal that can travel down a wire pair is a signal which has the voltage to current relationship consistent with the cable impedance. It does. You may or may not realize that is is impossible for a cable to carry a signal at the base propagation velocity if that signal has a V to I ration which is not that of the cable. Therefore, when an amp says "100 volts" into a cable which has a characteristic impedance of 100 ohms, that 1 amp signal will travel to the load at the line impedance. NOT THE LOAD IMPEDANCE. If the load impedance is 100 ohms, the event is over once the signal arrives, typically 2 nSec per foot. If the load is 10, one transit will NOT produce 10 amps into the load. It will take quite a few. Very important point... YOU ARE CLAIMING SUPERLUMINAL SIGNAL VELOCITIES. Doesn't happen. AND, what I am saying has been measured. Get a reflection bridge. you said: ""Information is power...get some."" pssst. I have news for you.. Be nice, get nice. Be arrogant, get same. John |
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 |
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 |
@ rower30, Read my 3-19-13 post,I have great respect for your knowledge,but remember,even when you have such profound education,and the fact you prefer data as means of proof,you cannot change what the humane ear hears!,I have told you 2 times in this thread my proof,that is humane hearing!,and the fact most audiophiles buy equipment based on what they hear!cheers! |
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. |
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 |
Balanced ICs would seem to be an easy solution, but a lot of home gear is not designed to use it. I have debated going to balanced myself on occasion, but frankly, I like my wire imperfections as a means of tweaking sound when needed. Just goes to show that the best technical solutions do not always win. |
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). |
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 |
I wonder is the impedance matching aspect that has been discussed of value only in theoretical discussion or is there a practical way to realize and assess the potential benefit? I suppose the best IC would be no IC. Integrated devices like integrated amps, with or without DACs, and traditional receivers are best suited to accomplish that. I wonder if there are ones that focus on the concepts relating to ICs discussed here to "connect" the sections of an integrated device optimally? Or does the nature of an integrated device, ie close proximity of components to connect together in the same chassis just render the issue of how to connect best practically moot? If there is a concrete significant benefit for an optimal IC versus those actually used in practice, that would seem to argue that integrated devices have a distinct advantage in that regard, ie everything "integrated" optimally by a designer out of the box so the user does not have to be concerned. That might be one reason to buy an integrated, though close proximity of components in a single chassis is probably a double edged sword and the potential for noise and interference a much bigger issue that works against the goals of optimal performance. That leaves one with the common path of keeping things separate and having to live with "imperfect" wires to connect everything. Oh well.... |
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 |
Please forgive me if I appear to be harping on one aspect of this multifaceted conversation. But, other than the added complexity(?) of perhaps needing a Zobel network to protect the amplifier, if all the other prescribed considerations are met, is there any harm in having a speaker cable with a characteristic impedance that is less than the speakers impedance? And with that aside for the moment; since most speakers have a varying impedance should one strive to have the speaker cables characteristic impedance match the speakers nominal, minimum, maximum or some other impedance? |
JN, thanks very much for the additional insights! All of which strike me as being highly plausible, notwithstanding the fact that I have never before seen them so stated. And I strongly second the subsequent comment by Corazon. I would commend to everyone else's attention the related comments you provided in the 2005 threads here and here. So if I understand your comment above correctly, skin effect is an even less important factor than even skeptics of the significance of that effect (myself included) may previously have envisioned. While the storage and delayed release of energy resulting from cable inductance and capacitance (as distinguished from the effects of "dielectric absorption" that are often referred to in cable marketing literature) are likely to be of greater significance than is generally realized. Interestingly, I recall that in past threads Ralph Karsten of Atma-Sphere, who as you may be aware frequently posts here under the screen-name "Atmasphere," has mentioned that many years ago various experiments he had performed indicated a correlation between sound quality and the closeness of the match between cable characteristic impedance and speaker impedance. That, of course, does not seem explicable on the basis of RF transmission line and reflection effects, and I had suggested in one of those threads the possibility that what he observed may simply have been the result of the low cable inductance that usually goes hand in hand with low characteristic impedance. I said that in part because the impedance of a dynamic speaker at the ultrasonic and RF frequencies for which reflection effects may become significant is usually much higher than it is at audio frequencies, primarily as a result of the inductance of the tweeter(s). This statement in one of your 2005 posts seems to reconcile it all elegantly: As it turns out, the point of minimal line storage occurs when the characteristic impedance of the cable matches the load..so, in theory, an 8 ohm speaker would work best with an 8 ohm cable impedance..this of course, is not because of reflections per se, but rather, just simply from the calculations of inductive and capacitive storage...So the bottom line, if I understand correctly, would seem to be that in the case of a speaker cable, and assuming that neutral behavior is desired, minimization of both inductance and characteristic impedance is desirable, up to the point at which characteristic impedance matches speaker impedance (at audio frequencies), with capacitance also being minimized to the extent that it is practicable to do so without significantly conflicting with those goals. Although, of course, whether or not truly neutral behavior will be subjectively perceived as optimal in a given system by a given listener will always remain an open question. Thanks again for the excellent and rarely stated inputs! Best regards, -- Al |
@ Jneutron,I like your position here with this post you stated!very realistic and comprehensive,with not to many words that mean nothing!,and the fact you gave help toward the cable industry is out standing!,I am nothing more than a consumer of cables,thou I have been around along time with my own inventions with resonance control and resonance tuning,sometimes science cannot explain everything!,to me if what a person created for sound works and sounds good to a fanbase of consumers than it must sound good and you feel like you are not waisting your time or others!,then there is the fact you claim that you are not immune to learning!,my setiments exactly,however,I will refuse to learn a science that dictates that what I hear does not exsist!,like cables signal flow is irrevelent,It may be possible for some brands of cables out there for this to really not matter,In my situation,a house full of 20 people and my self can hear clearly the difference signal flow made with top tier Taralabs cables!,for someone to state that all cables signal direction is irrevelent is very frustrating,how in the world can they base a finding with a few brands of cables out there and say, this is the way it is with all cables in the industry as a whole?,realisticaly that would take years of an attempt with a conclusion of failure!,the reason would be that most cable brands use different dielectrics,conductors,grounding schemes,the way conductors may be wound,are having no dielectric at all and have a vacume within the cable,the list can go on,I love learning,to me it is humane nature to test what someone claims,if there is no absolution,then to me the claim means nothing!cheers!,happy listening! |
Almarg, an excellent post. You are correct in interpretation of my 2005 statement, it is precisely what I said AND MEANT at that time. HOWEVER, my statement then is correct ONLY with respect to lines which have an impedance which matches the load. At the time I made the statement, I had not adequately considered what the extreme mismatch between load, line, and source would do with respect to the settling time of the speaker wire. As it turns out, the only time the naked propagation delay is valid, is when the load matches the line impedance. My concern is really only for midrange signals. It turns out that settling times for 10 foot zip cords which are terminated in 4 or 8 ohms midband, will be in excess of 5 uSec (Cyril Bateman actually measured this using a reflection bridge) and calculations bring that out in excess of 20 to 50 uSec. Given that humans demonstrate interaural discernment at the 2 uSec level give or take, this settling time falls within the possibility of audibility. You skin question...I don't see any way to post graphs here, so I'll have to use text. For a 1.5mm diameter wire at 20 Khz, the exponential solution states that at the center of the wire, there will be a current density which is 20% of the density at the surface. Using the exact solution, the current density at the center of the wire will be 72% of the surface current density. The exponential approximation is in error by a factor of 3.6 for a 1.5 mm dia wire at 20Khz. I am not a cable manufacturer. While I have designed cables, they are always for my own use. I have in the past, provided to at least one (maybe two) cable manufactureres, the equations and understandings to allow them to create any cable of any impedance they wish, either for their own use or for their product line. All information was given freely with no restrictions. Under no circumstances have I profited either monetarily or via materials as payment for information. All materials I have ever used to construct cables, either for test or private use, were funded by myself. In addition, the information given to that (or those) cable manufacturers is exactly what I have posted on multiple forums for all to use. The most important thing any technical person can do is to continue learning. Should that learning provide new insights and understandings which conflict with prior knowledge, so be it. Nature of the beast. I am not immune to learning either. jn |
"This is'nt new or rocket science, but as all components represent a different set of compromises, ergo, they will all sound different, because none are perfect." That's a very practical way of summarizing it! Few things are EXACTLY the same. Nothing is perfect. When comparing two wires, some may be so similar that no audible or significant difference exists. In other cases , so unique that differences are much more significant and likely to be heard. Like most things, its shades of grey, not black and white. My mantra is focus on things that are likely to make the biggest difference first. That is the way to get results. Do not spend all your time cutting hairs and expect to get anywhere. |
What an interesting discussion, I only understand one word in 10, but still, interesting. My 2 cents worth, does'nt the fact that cables sound different and most of us would agree they do make a difference to sound, mean that none are perfect? You come across this with all HiFi components, they are a set of compromises, change one component or material and you change the others. I think you see this most clearly with speakers. As a simple example, you can have high sensitivity or deep base, not both at the same time. If you spend a great deal, you will get nearer to deep base and high sensitivty, but money does'nt get away from the fact that you must make a choice. Similarly with cables, choosing to optimize one variable, say capacitance, effects the others. I can't see it is possible to make a perfect cable, amplifier or speaker, even if it were possible to get agreement on what perfect would be and it would'nt be possible to get said agreement. This is'nt new or rocket science, but as all components represent a different set of compromises, ergo, they will all sound different, because none are perfect. |
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JNeutron, thanks for your obviously very knowledgeable inputs. Yes, there are clearly a number of oversimplifications and "inaccuracies" (which I prefer to think of as "rough order of magnitude approximations") in what has been said in this thread. However, I would question whether or not the "inaccuracies" are relevant to the underlying points that have been made. For example, concerning your point about propagation delays I am aware that delays at deep bass frequencies can be far longer than the 1.6 ns/ft ballpark figure cited by the OP. At 20 Hz, for instance, I have seen data indicating that for many cable types delays may be 50 times or more greater than that figure. However, that would still equate to more than 2000 miles per second, which clearly corresponds to a negligible amount of time in the context of speaker cables in a home audio system. Based on the following comment you made in this 2005 thread, it appears that you would agree with that: I do agree that the term "prop speed" is rather confusing, as most seem to think it means that the transit time from the amp to the load is of any consideration...IT ISN'T [emphasis added]. But, the term prop speed is directly related to the DC [dielectric constant], L[inductance], and C[capacitance].I certainly don't disagree with that statement, and I doubt that the OP or most of the others who have responded above would disagree. Nor, I suspect, would they disagree with the following statement you made: But honestly, it's all in the R, L, C, and Q of the cable. Unfortunately, there's been so much mis-information spread around that high end audio guys end up guessing and trial and error, without much in the way of science..and, realistic measurement of matched Z cables is impossible for most wire vendors, as inductance measurements at the tens of nanohenry level are very difficult to do correctly.Regarding your points about skin effect, can you provide us with a QUANTITATIVE feel for the degree to which the result provided by an exponential approximation would deviate from the Bessel function result? For example, what would be the difference between the 63% skin depths at 20 kHz for solid core copper wire as calculated based on the two functions? Finally, a question I ask out of sincere curiosity: Do you design or manufacture audio cables, and if so, which ones? Regards, -- Al |
