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.
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.