The Truth About Power Cords and there "Real" Price to Performance

andy2,

An instability does not mean it has to oscillate, it could simply mean a settling issue, and to your point, an impact on the sound.

And no, turnbowm, my experience accidentally making more of a capacitor than a cable is not a perfect example. Kimber cable is typically 30-100pf/foot, I think the higher Cardas is close to 500pF/ft. I was close to 100nF for a 12 foot length.


turnbown, if there are no specific values for inductance/capacitance, then how do you know you were comparing cables with higher/lower values?

There are no specific values/limits for inductance and capacitance because of variables in the application. Your experience with amplifier instability using high capacitance speaker cables is a perfect example.

WRT:

the amp + speaker combination will affect the sound as the cable capacitance gradually changes. It’s not something that happens abruptly, like a 90 degree cliff.

Well, there is always the exception to "the Norm" - I know a guy that fried his Ayre amp and then fried a Gryphon integrated amp loaned to him - almost as soon as he turned each of them on.

The first failure he put down to simple component failure, but when the second amp fried very quickly after power on he suspected something else was the cause - I believed it to be his TOTL Cardas speaker cables which had a very high capacitance.

Since his system had worked prior to this event, we looked at what had changed.
He had just upgraded the power cable on the amp, so we believed the Ayre had probably been teetering on the brink of severe oscillation for a long time - then he upgraded the power cable and Ka-Boooom!

I believe the Gryphon fried almost as soon as he turned it on using the same cables.

We surmised the "improved performance" of that power cable was likely "the last straw" for both amps.

When we got the Gryphon back I loaned him some low capacitance speaker cables and all was well - but what surprised me is, the technician had never heard of this issue.

High capacitance cables are only an issue with some high current solid state designs - I am told by many sources that tube amps DO NOT suffer the same problem.

I have heard high capacitance cables might be preferable with certain amp/speaker combinations, but I have no experience of that.

But this is something audiophiles with solid state amps should be aware of.

I avoid high capacitance speaker cables for use with all my amps - just to be safe :-)

Regards - Steve

Well, there is always the exception to "the Norm"

Actually it's always analog.  What you interpret as "abrupt" or "sudden" or "just like that", in the analog world, there is always some "transitional curve".  The "transitional curve" may not be able to be "recorded" or "captured" by our perception or our ability since our brain cannot capture things like the oscilloscope can, but it's there.   

In order to have "just like that" in the real world, the energy required is "infinite".  Like a step response, on paper, it's abrupt.  But in the real world, there is no such thing as a "step response" since it would require "infinite" amount of energy.  

   "....if there are no specific values for inductance/capacitance, then how do you know you were comparing cables with higher/lower values? "

atdavid,

I always buy speaker cable in bulk and terminate them myself. I use mfg's published data and, if they don't provide it, I ask. Below are several examples that I've used....

Kimber 8TC:       Ls = 0.09uH/m
Mogami W3104: Ls = 0.6uH/m 

"....The first failure he put down to simple component failure, but when the second amp fried very quickly after power on he suspected something else was the cause - I believed it to be his TOTL Cardas speaker cables which had a very high capacitance...."

Goertz ribbon speaker cables also have high-capacitance that can be problematic to the degree that they offer a 'R/C Link' to combat amplifier instability issues. The R/C Link (aka, Zobel Network) is a resistor in series with a capacitor that is placed across the amplifier output to keep the demons at bay.