There’s an Audiogon discussion going on right now about optimal power cord length. The gist of the discussion is what’s the minimum length for a power cord? The poster is saying one (unnamed) manufacturer recommends a minimum of 1.8 meters. I searched the forums here and couldn’t find any discussion on the topic, so I’m putting the question out to PS Audio, is there a recommended minimum length? Beyond a minimum length, how does power cord length affect performance? I’ve always tried to keep my power cords short, going so far as to make my own using some DH Labs bulk cable I got from Parts Connexion. I have tried a 0.5 meter AC-12 which is incredibly stiff, a longer length would be easier to route, but that’s not a performance advantage, per se. I’ve also used an older mini Lab cable which wasn’t too bad for routing, but quite honestly I don’t recall if it made a difference in the sound (heresy?). Thoughts?
Fun question.
Given the claims as to how power cords work, I would think the longest you could afford would be the best.
Do any of the manufacturers make recommendations?
I did a quick search and found the unnamed manufacturer, LAT International, who states “… any length shorter than 1.8 meters (5.9) ft. will begin to degrade the effectiveness of the shielding and filtering capabilities; regardless of who is the manufacturer. Power cords are not like speaker cable and interconnects where shorter is better.” Kind of a bold statement. No other posters quoted manufacturers recommendations, though one poster said he knew of one that recommended 3 feet minimum, but not sure who the manufacturer is. As one wag said “I think the manufacturers just want to sell us more wire.”, probably more truth in that than the manufacturers will admit!
I should add that the cord the quote came from was the AC-1, which was only $99 for the 1.8 meter length. Hard to complain about that price and taking more of our money, but still they applied the logic to all manufacturers.
I’ve not seen this thread in question, but I’ve had a couple power cable manufactures tell me that you do need a longer power cord to really reap the benefits of the filtering etc. While the idea does sound like it could be true, I agree it could simply be an upsell.
With my setup, different (high end!) power cords just don’t seem to make much of a difference. My amp is pretty agnostic due to it’s huge filtering caps (originally designed for use in some nuclear power plant I’m told).
That said, I’m a firm believer in an excellent ground to the house to lower resistance and give noise a place to go. So I could be convinced a well built power cord could “filter” if you had need, and your ground resistance was nice and low. 
Raven, I sent you a private message earlier.
Well it certainly is logical that if a power cord is a filter, a longer cord would provide more filtering. But how much filtering (i.e., length) is enough and can you get too much? What I was expecting is PS Audio (Paul, Dennis, whoever) to reply and give their opinion. Strangely they have been silent.
Sorry guys, been buried. The answer here is somewhat obvious although the reasons for it are not. Every power cord has an effect on the sound: better, worse, etc. The longer that cable is the greater the change.
So, for example, let’s say you have a stock POS 16 gauge power cable. Your unit will perform and sound a certain way. make that cord longer, perhaps a lot longer, and those effects of the power cable become exaggerated. Most stock POS cables make your equipment sound thin, 2-dimensional and restrict depth, soundstage and separation of instruments. The longer the cable the more you hear this effect.
Now take a non-POS cable. A good one. Like one of our AC series cables. These have the opposite characteristics of those I’ve just described. Dynamics are improved, width, depth, separation fullness.
Now here’s the first interesting bit. Between the two statements of performance above, the question comes to mind “as compared to what?” The quick answer is, the PS AC series power cable is better in all respects (as mentioned) to the POS cable. So, is it just fixing the POS problems or doing something else? If the former, then the longer the PS AC cable got the poorer the improvements. If it were the latter, then the longer the PS AC cable, the more improvements one would get.
Some aftermarket cables filter, some don’t. We made a series of power cables years ago with powdered ferrite in the jacket for cleaning. These seemed to get better with length.
Stock cables get worse with length because they are restricting the power delivery and acting as antenna for radiated crap.
Our present AC series of power cables does a bit of cleaning, but its design parameters are based on the “do no harm” theory and, as such, probably have an optimal length.
In closing, there does seem to be a sweet spot for power cables and I am not entirely sure why; I have my own guesses but will keep them to myself for now. I generally find 2 meters to be about optimal, depending on the make of the cable and considering we’re not talking POS here - I am referring only to the “good stuff” in cables.
As with most non-simple things . . .
It depends. 
Thanks for the reply Paul. On one hand your take on the subject is a surprise, but on the other hand it’s sort of what I expected. I was somewhat surprised that you don’t consider your cables as filters and they, as you put it, “do no harm”. What really surprises me is to “do no harm” I would expect shorter is better, get the power to the component without impeding it, but the stated observation is approximately two meters is a good length. This indicates to me there is a mechanism at work other than just passing the power without doing harm. The fact that you don’t know specifically how it works shouldn’t be surprising though, given how many things in this hobby defy rational scientific explanation. Bad news for me is I don’t have a single power cord over one meter, replacing them and a DS kit still in my future means the bank account won’t be happy!
pmotz said Thanks for the reply Paul. On one hand your take on the subject is a surprise, but on the other hand it's sort of what I expected. I was somewhat surprised that you don't consider your cables as filters and they, as you put it, "do no harm". What really surprises me is to "do no harm" I would expect shorter is better, get the power to the component without impeding it, but the stated observation is approximately two meters is a good length. This indicates to me there is a mechanism at work other than just passing the power without doing harm. The fact that you don't know specifically how it works shouldn't be surprising though, given how many things in this hobby defy rational scientific explanation. Bad news for me is I don't have a single power cord over one meter, replacing them and a DS kit still in my future means the bank account won't be happy!
I’m glad Paul said “do no harm”. One thing I’ve regularly appreciated about Paul, is the no BS and pixie dust. If he says something sounds good, “but I don’t know why”, I take him at his word. It’s better than some others that spout psudo-scientific crap.
Anywho, back to the Do No Harm - I’m a firm believer in power cords being “do no harm”. If you need a longer length, you need to have the bigger gauge wire. If it’s going to be in a position that it’s going to pick up noise, then it needs to be shielded. I don’t believe there is any magical combination that makes things better…either it works and “does no harm”, or it’s changing something that causes an effect down in the power supply. Or maybe it’s just crap. LOL
Lonely Raven said One thing I've regularly appreciated about Paul, is the no BS and pixie dust. If he says something sounds good, "but I don't know why", I take him at his word. It's better than some others that spout psudo-scientific crap.Yes! This is the intellectually honest approach.
One of the many things I appreciate about Paul and Ted.
Thanks guys. Just to be clear, I don’t believe there’s any cable that “does no harm”. They all do harm, some less some more. What I intended to get across in my comment was not that our power cables do no harm, but that the intent behind their design was to do as little harm as possible. We also want to make perfect audio equipment; but of course don’t. Intent and results aren’t always the same. 
Paul McGowan said Thanks guys. Just to be clear, I don't believe there's any cable that "does no harm". They all do harm, some less some more. What I intended to get across in my comment was not that our power cables do no harm, but that the intent behind their design was to do as little harm as possible. We also want to make perfect audio equipment; but of course don't. Intent and results aren't always the same.
So that begs to ask: What’s holding you back, Paul? What’s the hurdle, or compromise that keeps your power cables from completely doing no harm?
Physics. Reality. You cannot pass electricity through a conductive medium without affecting it. It is not theoretically possible to move current down a conductor without generating a magnetic field, without losing something in the process.
So as designers we simply do the best we can to minimize the damage.
Paul McGowan said Physics. Reality. You cannot pass electricity through a conductive medium without affecting it. It is not theoretically possible to move current down a conductor without generating a magnetic field, without losing something in the process.So as designers we simply do the best we can to minimize the damage.
Maybe it’s time you set some smart guys on room temperature super-conductors then, Paul? 
“The Best Power Cable, Is NO Power Cable”.
Given what the external grid does to our incoming power, it kinda makes sense to incorporate some form of filtering or realigning technology into the design structure.
Even a re-generator is limited when attempting to tame an electricity “bad hair” day.
The AC-12 cable does make a difference feeding my P-5. Didn’t think that it mattered much as long as the cable gauge was sufficient to carry the current for maximum regeneration.