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.
...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.