Would be a good thread to discuss plausible reasons for why we may be hearing differences in cables.

Cable engineering is a well-understood science. That is why engineers are able to design cables to pass higher and higher speeds for computer networking, and higher and higher current for power transmission. For example, a Cat7 cable allows 10 Gigabit Ethernet over 100m, and is rated for a transmission speed of 600MHz. That is far, far above any frequency needed for audio.

No cable is perfect, and any loudspeaker cable or interconnect can be modeled as follows.

Loudspeaker designers will recognize this as a low-pass filter. However, the filter effect at audio frequencies is negligible with the values that are encountered in cable design.

There are three key electrical parameters that are all easily understood.

Resistance can be determined by size and material. 12 awg stranded copper wire has a resistance of 5.3ohm per kilometer (1.6ohms per 1,000ft). Go up to 10awg and it falls to 3.3 ohm/km, go down to 14awg and it rises to 8.5 ohm/km. Purity makes a miniscule difference to the resistance above about 99.5% pure. Silver has about 5% lower resistance than copper all else being equal.

Pure resistance causes a voltage drop, and does not affect frequency response and phase characteristics of the signal. The resistance needs to be sufficiently low that the voltage drop from one end of the cable to the other is negligible when terminated into the expected impedance.

Whenever electrons flow through a conductor, a magnetic field will develop around that conductor. The more current that flows, the stronger the magnetic field. This magnetic field stores energy, and when the current stops, the collapse of the field returns energy to the conductor. Since this occurs between the amplifier and the loudspeaker, the sonic result is a smearing of detail.

The measure of this effect is inductance, and high inductance causes a cable to store and release current. Thus, a cable with high inductance can be regarded as “powerful” and “full bodied”. Intuitively, we can understand that this store and release of energy also causes a smearing of the signal.

When we build a cable, the two wires that carry current in opposite directions can be placed close one another so that the inductance can almost cancel out. The closer the two wires are to each other, the greater the cancellation effect and loop inductance can approach zero.

Whenever a voltage exists between two separated conductors, an electric field will exist between those two conductors. The two conductors with the insulator in between will act as a capacitor which stores and releases energy.

Capacitors tend to resist changes in voltage between the two conductors. Hence, when the voltage is increased or decreased (as when a musical signal flows), the capacitor resists the change by drawing current from, or supplying current to the source of the voltage change in opposite to the voltage change. Since this is in parallel between the source and the destination, the capacitance acts as a shunt across the cable and the sonic result is the blunting or softening of transients and dynamics.

This effect can be measured in a cable as capacitance. A cable with higher capacitance can be said to be “sweeter” or “smoother” as a result. The closer the two conductors are together, the higher the capacitance.

While the range of inductance (micro-Henrys) and capacitance (pico-Farads) are sufficiently small that they should not result in significant frequency response distortion, we can hear the store and release of energy as distortion in the soundstage, a smearing of micro-dynamic detail and a loss of focus.

Some cables are optimized for the lowest possible inductance at the expense of high capacitance. It is easy to recognize these cables as they will have multiple insulated conductors that are tightly braided or spiraled together. The more expensive they are, the more conductors there are, and the higher the capacitance!

Other cables are optimized for the lowest possible capacitance at the expense of high inductance. These easily identified as they will have two conductors that are widely spaced and held apart. In these cables, a larger conductor results in lower inductance, but not by enough that it matters much.

If we then believe that we can hear this inductance and capacitance in a cable (and I know that I can hear it), then we need to balance between inductance and capacitance. Since current matters to inductance, and voltage matters to capacitance, we start to have a clue.

High current loudspeakers should have cables optimized for lower inductance, and high efficiency loudspeakers should have cables optimized for capacitance. To give some numbers, I have three designs:

i) a high-current loudspeaker cable that has a loop inductance of 0.06uH/ft and a capacitance of 43pF/ft;

ii) a high-efficient loudspeaker cable that has a loop inductance of 0.11uH/ft and a capacitance of 24pF/ft;

iii) one in between that has a loop inductance of 0.10uH/ft and a capacitance of 32pF/ft

... all measured at 1kHz.

There is much hay made by marketing people about Teflon being the best insulator because it makes the cable “faster” due to the low dielectric constant. However, in terms of transmission speed of the signal from one end of the wire to the other, it doesn’t make much sense.

Nevertheless, the dielectric constant is an essential factor in the design of a capacitor. A higher dielectric constant would be used to increase the capacitance of a particular design. Hence, when we design a cable to minimize inductance and capacitance, using an insulator of lower dielectric constant decreases the capacitance of a particular design. All things being equal, with the same distance between the two wires to keep inductance constant, going from a PVC insulator to a Teflon insulator would halve the capacitance of the cable.

A second reason to use Teflon is that it has the lowest dielectric soakage. This is the capacitor’s propensity to regain charge after a short circuit. Intuitively, the dielectric soakage is also a form of storage of energy, hence, looking for a material that would not do this would result in a cable that would have better micro-dynamic detail.

No cable is perfect, and any loudspeaker cable or interconnect can be modeled as follows.

Loudspeaker designers will recognize this as a low-pass filter. However, the filter effect at audio frequencies is negligible with the values that are encountered in cable design.

There are three key electrical parameters that are all easily understood.

**1) Resistance (R1 and R2)**Resistance can be determined by size and material. 12 awg stranded copper wire has a resistance of 5.3ohm per kilometer (1.6ohms per 1,000ft). Go up to 10awg and it falls to 3.3 ohm/km, go down to 14awg and it rises to 8.5 ohm/km. Purity makes a miniscule difference to the resistance above about 99.5% pure. Silver has about 5% lower resistance than copper all else being equal.

Pure resistance causes a voltage drop, and does not affect frequency response and phase characteristics of the signal. The resistance needs to be sufficiently low that the voltage drop from one end of the cable to the other is negligible when terminated into the expected impedance.

**2) Inductance (L1 & L2)**Whenever electrons flow through a conductor, a magnetic field will develop around that conductor. The more current that flows, the stronger the magnetic field. This magnetic field stores energy, and when the current stops, the collapse of the field returns energy to the conductor. Since this occurs between the amplifier and the loudspeaker, the sonic result is a smearing of detail.

The measure of this effect is inductance, and high inductance causes a cable to store and release current. Thus, a cable with high inductance can be regarded as “powerful” and “full bodied”. Intuitively, we can understand that this store and release of energy also causes a smearing of the signal.

When we build a cable, the two wires that carry current in opposite directions can be placed close one another so that the inductance can almost cancel out. The closer the two wires are to each other, the greater the cancellation effect and loop inductance can approach zero.

**3) Capacitance (C1)**Whenever a voltage exists between two separated conductors, an electric field will exist between those two conductors. The two conductors with the insulator in between will act as a capacitor which stores and releases energy.

Capacitors tend to resist changes in voltage between the two conductors. Hence, when the voltage is increased or decreased (as when a musical signal flows), the capacitor resists the change by drawing current from, or supplying current to the source of the voltage change in opposite to the voltage change. Since this is in parallel between the source and the destination, the capacitance acts as a shunt across the cable and the sonic result is the blunting or softening of transients and dynamics.

This effect can be measured in a cable as capacitance. A cable with higher capacitance can be said to be “sweeter” or “smoother” as a result. The closer the two conductors are together, the higher the capacitance.

While the range of inductance (micro-Henrys) and capacitance (pico-Farads) are sufficiently small that they should not result in significant frequency response distortion, we can hear the store and release of energy as distortion in the soundstage, a smearing of micro-dynamic detail and a loss of focus.

Some cables are optimized for the lowest possible inductance at the expense of high capacitance. It is easy to recognize these cables as they will have multiple insulated conductors that are tightly braided or spiraled together. The more expensive they are, the more conductors there are, and the higher the capacitance!

Other cables are optimized for the lowest possible capacitance at the expense of high inductance. These easily identified as they will have two conductors that are widely spaced and held apart. In these cables, a larger conductor results in lower inductance, but not by enough that it matters much.

**Loudspeaker Cable Design**If we then believe that we can hear this inductance and capacitance in a cable (and I know that I can hear it), then we need to balance between inductance and capacitance. Since current matters to inductance, and voltage matters to capacitance, we start to have a clue.

High current loudspeakers should have cables optimized for lower inductance, and high efficiency loudspeakers should have cables optimized for capacitance. To give some numbers, I have three designs:

i) a high-current loudspeaker cable that has a loop inductance of 0.06uH/ft and a capacitance of 43pF/ft;

ii) a high-efficient loudspeaker cable that has a loop inductance of 0.11uH/ft and a capacitance of 24pF/ft;

iii) one in between that has a loop inductance of 0.10uH/ft and a capacitance of 32pF/ft

... all measured at 1kHz.

**What about Teflon/Air used as a dielectric?**There is much hay made by marketing people about Teflon being the best insulator because it makes the cable “faster” due to the low dielectric constant. However, in terms of transmission speed of the signal from one end of the wire to the other, it doesn’t make much sense.

Nevertheless, the dielectric constant is an essential factor in the design of a capacitor. A higher dielectric constant would be used to increase the capacitance of a particular design. Hence, when we design a cable to minimize inductance and capacitance, using an insulator of lower dielectric constant decreases the capacitance of a particular design. All things being equal, with the same distance between the two wires to keep inductance constant, going from a PVC insulator to a Teflon insulator would halve the capacitance of the cable.

A second reason to use Teflon is that it has the lowest dielectric soakage. This is the capacitor’s propensity to regain charge after a short circuit. Intuitively, the dielectric soakage is also a form of storage of energy, hence, looking for a material that would not do this would result in a cable that would have better micro-dynamic detail.