audiphile power cords

Please do Ralph!

Alright...

With power cords its all about voltage drop across the cord. Some of that is at 60Hz, and some of that is much much higher- well above 30KHz-100KHz depending on the power supply in the unit with which it is being used.

I've seen a 2 1/2 volt drop rob an amplifier of about 30% of its output power. The cord was rated for 10 amps, and the draw was about 6 amps. This measurement was done with a simple 3 1/2 digit Digital Voltmeter.

The more insidious problem is high frequency bandwidth. The power supplies of most amplifiers have a power transformer, a set of rectifiers, and a set of filter capacitors. The rectifiers only conduct when the power transformer output is higher than that of the filter caps. So:

When the caps are fully charged the amp is able to play. As it does so, the caps are discharged until the AC line voltage waveform gets high enough again that the rectifiers in the power supply are able to conduct. Depending on the state of charge of the filter capacitors, this might only be for a few microseconds or it might be a few milliseconds. Either way, the charge is a spike which has very steep sides- and requires some bandwidth to make it happen.

If the power cord has poor high frequency response, it will current limit on these spikes. This can result is subtle modulations in the power supply or even a sagging power supply voltage.

Romex wiring found in many buildings actually works quite well. So it really becomes all about that last few feet and also how well the power cord is terminated- molded cords generally are not terminated very well. If the ends of your power cord get warm after a while, you know you have a problem!

This can be measured, its quantifiable and also audible as many audiophiles know. Anyone who tells you differently probably has not bothered to do any measurements- please refer them to this post.

I can go into more depth but this is it in a nutshell. Incidentally, Shunyata Research is refining an instrument that does a more in-depth analysis of what this is all about. At the link you will see that their tests essentially confirm what I have said here.

http://www.theaudiobeat.com/visits/shunyata_visit_interview.htm

Nglazer +1

Atmasphere +2

We've been through all of this before but I guess it's better than reality TV (please, tell me no one here watches reality TV).

Or the false meme that the science isn't settled on whether or not climate change is man made.

All the best,
Nonoise

Ralph's explanation makes sense in teh case of power cords for amplifiers in general where efficient current delivery and bandwidth are very important.

Some vendors focus more on noise reduction and positive effect of that on distortion for power cords designed for line level gear, especially those that are digital.

I tend to agree that the problem to address is different for noise sensitive line level gear versus current hungry power amps, so best to tackle each problem uniquely when designing a suitable power cord.

Hello Abrew19,
You are spot on regarding Climate change and science. It has become corrupted by political agendas unfortunately.Listen to NPR for a while and you can't help but notice the bias.Opposing viewpoints aren't tolerated. Sad, as science should be open to all perspectives not just the politically chosen ones.
Charles,

It always amazed me when I hear a pseudo-engineer say "cords can't make a difference if they are adequately sized". No engineer would argue that the following things can indeed make a difference, and are measurable:

- different gauges
- different dielectric materials
- different configuration (twisted, braided, side-by-side, etc.)
- different metals
- stranded vs solid
- shielded vs unshielded

So of course cords make a difference. But the art is in figuring out how a particular type of cord will interact with any given component, let alone why, and what effect is to be expected in the resulting sound. That is not so straightforward.