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.
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.