Do power cords make an audible difference?

09-22-10: Johnnyb53
It doesn't "kinda prove the point." You're pitting your long distance pre-formed opinion against a reported experience."

My long distance pre-formed opinion is about as reliable as someone hitting play and saying "Whaddaya think?" I never said the PC did not make a diff, I did say that many people completely disregard everything we know about how people perceive the world around us, that's all.

You started at the right place with the right product, my man. If I would have known this from the get go, I would have saved a lot of money on interconnect and speaker swaps.

Sebrof: Tuesday night I was wearing blue jeans and my system sounded very good to me. Wednesday night I was wearing slacks and it sounded just a little better. I do not conclude that slacks make my system sound better.

For a specific example that supports Sebrof's comment, see the posts by Atmasphere and me in this thread, which illustrate how easy it can be to attribute a perceived sonic attribute to the wrong variable. For easy reference, following are the relevant paragraphs:

Atmasphere: Power cords: a 2V drop across a power cord can rob a tube amplifier of as much as 40% of its output power! Cripes! You're trying to say you can't hear that?? So this is very measurable and audible as well. On lesser transistor amps, a power cord will be less audible as the drop across the cable is reduced, but a class A transistor amp will easily bring out cable weaknesses.

Almarg: Ralph, could you provide a technical explanation of why that would be so? I don't doubt your statement, but I'm interested in understanding why that would occur.... Re your other points, all of which strike me as excellent, I think that it should be stated that none of those points NECESSARILY mean, to cite an example, that a $2,000 power cord will outperform a $200 power cord in any given system.

Atmasphere: Al, the reason a power cord can have this effect is simple. If there is a 2 volt drop in a power cord, the filaments of the tubes will run cooler and the B+ will be reduced. Since this is a voltage, the result is we get less voltage output out of the amp. Less voltage=less power. Depending on the amp this can be pretty profound. and I have seen it with my own eyes. I do agree though that that does not justify a $2000 power cord, but it **does** justify one that has decent connectors and conductors that will not heat up at all. That has to cost something, probably not $2000 though. One thing about audio is that if there is a phenomena, there is also snake oil for it.

Almarg: Thanks, Ralph. That would also seem to say that the value of the ac line voltage at each listener's location can be a very significant variable in the performance of a tube amp (assuming it does not have regulated filament and B+ supplies). Which in turn emphasizes how easy it can sometimes be for extraneous variables to lead to incorrect sonic assessments.

Atmasphere: No doubt! But it extends to anything that can draw significant power- and bigger transistor amps can! Imagine the peaks just... not... making it.

This taught us a lesson... when we set up an amplifier for test, we test the AC line voltage from the IEC connector. The meter on the variac (a bit of test instrumentation) cannot be trusted.

Regards,
-- Al

@Photon46, I was not pulling your leg. A friend of mine told me that if I could not hear the difference of a power cord he loaned me, my system could not be high end. Maybe he was right. I didn't hear any difference.

A friend of mine told me that if I could not hear the difference of a power cord he loaned me, my system could not be high end. Maybe he was right. I didn't hear any difference.

IMO it is a common fallacy to assume that system quality and musical resolution necessarily correlate with the ability to resolve differences in components, cables, or power.

Certainly that CAN be the case. However, consider some examples where it is not.

A speaker having impedance characteristics that fluctuate widely over the frequency range, drop to low values at some frequencies, and have difficult phase angles, will be much more revealing of amplifier and speaker cable differences than one that presents an easy load.

A source component or preamplifier with a high output impedance will be more revealing of differences in interconnect cables than one with a low output impedance.

An electronic component that has unbalanced interfaces will be more sensitive to differences in interconnect cable shield resistance if it has higher stray capacitance and ac leakage paths in its power transformer (which increase sensitivity to ground loop issues).

And, addressing specifically the subject matter of this thread, increased sensitivity of an amplifier to power cord differences can be the result of looser regulation in the amp's power supply. Or it can be the result of greater amounts of high frequency noise being produced by that power supply, which increases the need for effective shielding in the power cord, to prevent that noise from coupling to other parts of the system. Or it can be the result of poor shielding or greater sensitivity to that noise elsewhere in the system. Or it can be the result of poor rejection by the amp's power supply of noise or distortion on the incoming ac.

None of those kinds of factors mean that the system that is more resolving of cable or component or power differences will be more resolving of musical detail, or capable of higher quality music reproduction. They just mean that it may be more difficult to attain optimal results with that system.

Regards,
-- Al