Why is high capacitance good?

Just a guess.

Well, you certainly don't want higher capacitance with longer cable runs. Higher cable capacitance will make the load values on either end more critical to proper matching. This is why folks recommend as low a capacitance as possible with long cable runs.

I find that the cables I've tried with high capacitance usually sound warm, bloated and slow. However, I'm sure that there are systems where these cables work.

In itself, high capacitance in a speaker cable is not good. And with some amplifier designs, especially marginal ones, it can lead to poor sound, oscillations, or even damage, unless a Zobel Network is used to compensate.

However, high capacitance can be a side effect of designing the cable to have ultra-low inductance. Low inductance being likely to improve the neutrality of the cable, everything else being equal, although lowering it beyond a certain point will be unnecessary overkill.

High capacitance can also be the intended result of designing the cable to have extremely low characteristic impedance, characteristic impedance being approximately equal to the (square root of (inductance per unit length divided by capacitance per unit length)).

Some speaker cables are marketed based on the theory that their characteristic impedance should approximately match the speaker's impedance. Although I don't question that those cables can and do provide excellent performance in many systems, imho that theory makes little sense, and imho that theory is not what accounts for their performance. I say that for two reasons:

1)For any remotely reasonable cable lengths, characteristic impedance is a concept that is only applicable at frequencies in the radio frequency range, or that at least approach being in the rf range. At those frequencies, the cable's characteristic impedance should closely match the impedance presented by the load, or some of the incoming energy will not be absorbed by the load and will be reflected back toward the source, creating what are known as vswr (voltage standing wave ratio) problems.

2)At the high frequencies at which characteristic impedance may begin to become significant, speaker impedance will be much different than it is in the audio range.

I calculate based on the published capacitance and inductance numbers for the particular cable you referred to that its characteristic impedance is around 5 ohms, right in the vicinity of typical speaker impedances at audio frequencies.

For more conventionally designed cables that figure would typically be in the rough ballpark of 75 or 100 ohms. Which, interestingly, is probably a much better match to the impedance of typical dynamic speakers at frequencies that are in the lower part of the rf range, where the effects of characteristic impedance may start to become significant. Tweeter voice-coil inductance will cause the speaker impedance to rise substantially at those frequencies.

That said, based on user comments many of those cables do give excellent results in many systems. And the combination of inductance which is low to the point of overkill, with capacitance that is unusually high, would certainly seem likely to make them sound DIFFERENT than more conventionally designed cables.

Best regards,
-- Al

To get rid of any negative effects of capacitance, inductance etc - Spectron Audio use "Remote Sense" speaker cables, see - http://spectronaudio.com/cables.htm.

Basically they take full advantage of their ultrafast feedback loop and include speaker cable into it - making amp/speaker the single amplification system.

Does anybody else use the same concept?

Thank you

Al- thanks for the detailed (and fascinating) response. How high are radio frequencies that you mention? Some of these particular cables may actually attenuate high frequencies (MIT with Wilson seems to be a popular combination because of it) so perhaps you are right.

KeithR