[ericj]

Lets presume that a 'good' power cable exists that does whatever it does without the help of ohmic resistance, capacitance, or inductance. Which is quite a stretch, lemme tell ya.

Lets say it's completely perfect in every way and introduces not one single burp of schott or johnson noise.

Hell, lets say it's supercooled so that it doesn't introduce any thermal noise.

How is it not roughly equivalent to deleting three feet of wire distance between you and the breaker box?

It should logically be equivalent to moving to another outlet.

And as others have pointed it, it is apparent that the device that it's powering is so sensitive that you should be able to hear a remarkable difference in quality depending on whether your neighbor's AC compressor is running or not, for example.

 

[philodox]

I'm not interested in explaining, nor do I have the technical expertise to explain, the reason that a decent power cord makes an audible difference in my headphone rig. I completely agree with your logic, for what that is worth, but I don't second guess my experiences based on logic.

As I said earlier, I can't recall if I ever compared 'high end' power cords straight out of the wall. As far as I know, I've always used a power conditioner and then ran the good PC from there. Does that seem more plausible to you?

 

[UserNotFound]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Sure do, what would you like to know?

Well, for starters you could throw some ideas out there on how noise on the power supply makes it's way from the mains line to your headphones. I mean after all, there's a ~110V 60Hz "sine" wave going in, you should be able to explain how noise couples itself through the system given whatever supply topology your device uses. Things like PSRR should come to mind, for starters.

Quote:

Originally Posted by philodox /img/forum/go_quote.gif I'm not interested in explaining, nor do I have the technical expertise to explain, the reason that a decent power cord makes an audible difference in my headphone rig.

It's really quite simple, and you don't have to be an EE with a background in RF to explain it : placebo.


Does anyone have an electrical engineering degree and still believe a power cable makes a difference anywhere near audible? Because I spent 4 weeks in lab on this topic with hundreds of thousands of dollars of equipment, including an anechoic chamber, and am amazed by these claims.

 

[304290]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif Do you have any idea what's in the walls of your home? It's 14awg solid copper - nowhere near OFC, and three in a flat row. All through your house. How, presicely, are you going to avoid this noise and electromagnetic interference with a damn cable? We are in the DIY forum, not the cables forum. If you want to argue it subjectively, go to the cables forum, and i promise i won't follow you. But we're in the DIY forum, so you're going to have to state some science here. No matter how oxygen-free or pure or made-of-silver a cable is, it's going to deliver RF noise unless you leverage higher impedance, inductance or capacitance to attenuate it. So explain to me how a "better" cable does this without being a halfassed, expensive mockery of a simple filter circuit?

Read the tread. The reason it is in the diy forum because the cord is a diy cord made from wire purchased from lowes. I never said a power cord would eliminate electromagnetic interference. What is said is a cheep power cord would introduce more than you already have coming through your outlet, and an upgraded cord wouldn't add as much as you already have coming through your walls so get your damn facts straight.

 

[ericj]

Quote:

Originally Posted by 304290 /img/forum/go_quote.gif I never said a power cord would eliminate electromagnetic interference. What is said is a cheep power cord would introduce more than you already have coming through your outlet, and an upgraded cord wouldn't add as much as you already have coming through your walls so get your damn facts straight.

But there's probably a mile and a half of romex in the average house. The very cheapest of UL-listed AC power cords aren't any more sensitive to EM than romex. If you get a nice one - one with twists in it - then you're using inductance.

 

[IcantHearU]

Wouldn't a 'better' cord more accurately reproduce any crap on the lines than a 'lesser' wire - and if that's the case, well....

(I'm just playing devil's advocate - I have not ever performed a true A/B test with varying quality/price power cords)

 

[ericj]

That's basically my position. It's not about clarity, it's about attenuation. The power signal is a f'in disaster.

In order to have less of the noise, you need a circuit that has a low impedance for 60hz (50hz in the EU) and a high impedance for higher frequencies.

 

[Sarchi]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif I always wonder about all the other factors affecting the power grid. Not just the other cables running to the house, but how the grid ebbs and flows depending on the loads and capacity. How different generators go on and off line. How the weather affects transmission, how the sunspot cycle changes the amount of RF absorbed by the grid's equipment, employees constantly upgrading and changing out various equipment, and dozens of other variations. These are all real events that really happen. If systems are so sensitive that 3' of cable change the sound, then there must be a massive change in sound every time a different plant goes on line and another cycles out. Heck, plants built 25 years apart MUST sound different. How could they possibly sound the same? What I find curious is that the power grid, demonstrably, undergoes massive change every minute. Literally. A system sensitive enough to resolve the difference between power cords should resolve the difference between power stations, as well as everything mentioned above. To argue that power is constant is madness and demonstrably wrong. Therefore, you would expect a system to sound different, minute by minute. Maybe power cords do make a difference, but how could you ever distinguish that from every other variable? If you insist that minute differences in cable construction change the sound, you have to accept that every other variable upstream plays a part.

Very true. And this is no doubt a factor when you notice how much better your system sounds late at night. Or as some audiophiles have found, when you power more of your gear from a battery supply.

 

[philodox]

Quote:

Originally Posted by UserNotFound /img/forum/go_quote.gif Well, for starters you could throw some ideas out there on how noise on the power supply makes it's way from the mains line to your headphones. I mean after all, there's a ~110V 60Hz "sine" wave going in, you should be able to explain how noise couples itself through the system given whatever supply topology your device uses. Things like PSRR should come to mind, for starters.

Sorry, but it is common knowledge that switching power supplies feed noise back on to power lines. Do you really need me to explain that to you? Quote:

Originally Posted by UserNotFound /img/forum/go_quote.gif It's really quite simple, and you don't have to be an EE with a background in RF to explain it : placebo.

Are you saying that because I am not an Electrical Engineer I am responding to placebo? If so, that is absolutely crazy. Quote:

Originally Posted by UserNotFound /img/forum/go_quote.gif Does anyone have an electrical engineering degree and still believe a power cable makes a difference anywhere near audible?

Actually, in previous power cord discussions, a few EE's have thrown down, and they weren't always on your side.

 

[UserNotFound]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Sorry, but it is common knowledge that switching power supplies feed noise back on to power lines. Do you really need me to explain that to you?

Why did you choose to use a switching power supply? Using a different power cable seems to be the least effective method of noise elimination in your system that you so carefully explained it to me. I'm going to continue to doubt the effectiveness of whatever cable you happened to use with whatever equipment it happens to be connected to until I know what they both are.

Is there just a generic "nicer cable" or are there specific cables for specific power supply topologies?

 

[philodox]

I'm not using a switching power supply, but every computer, fridge, etc in my condo building is... All this noise builds up in the grid and can wreak havoc with linear PSU's. This is especially noticeable in audio. Before you pull your EE card, it was an EE that first explained this to me.

Like I said earlier, I am not sure that I've done any tests with just the power cord. When using my power conditioner, a UPC-200, the better cord makes a difference over a stock cord with my CD player.

I'm not an advocate of spending a lot of money on power cords, so I'm sorry if you got that impression. I do think that using a good power cord can give you a positive improvement over a stock cord though. The power cord that I use with my CD player is very well made, uses large gauge silver plated copper stranded wire, has shielding, and some nice oyaide clone connectors on either end. It cost me $0, as it came for free with my CD player since I know the seller.

I'm happy for the OP, since he seems to have found a cheap power cord 'recipe' that has improved his rig.

EDIT: My amp seems to be immune to any of this for what it is worth. Sounds the same straight out of the wall as it does out of my power conditioner. I am so happy with how it sounds that I haven't bothered trying any other power cords, but I may do so in the future. I'm not sure why this is the case. Perhaps digital gear is more sensitive than analog? Perhaps the extremely large power transformer on my amp helps it reject noise?

 

[UserNotFound]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif EDIT: My amp seems to be immune to any of this for what it is worth. Sounds the same straight out of the wall as it does out of my power conditioner. I am so happy with how it sounds that I haven't bothered trying any other power cords, but I may do so in the future. I'm not sure why this is the case. Perhaps digital gear is more sensitive than analog? Perhaps the extremely large power transformer on my amp helps it reject noise?

I wasn't trying to pick on you, I'm just frustrated that in a DIY forums, nobody seems to say anything but "it has properties that could be more ideal", with no reference to their system.

My particular amp has a linear power supply with a rejection ratio measured at 76dB (not just the regulator, the supply as a whole, as measured by myself, under full load). Couple with another 100dB rejection at the opamp, I have yet to experience any noise at all, either, and would try a 100 different things first to improve my sound before I might even consider the power cable.