|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.222.96.226
In Reply to: power cords-the last meter posted by obichni on February 12, 2007 at 14:08:22:
First, the "miles and miles" of power lines is a neat tidy FALLACY that gets used to turn off the brain from thinking.As some folks have pointed out, it can certainly be looked at the other way, that the power cord is the first M, not the last, and in like manner, that it is an extension of the power supply wiring.
But the fact of the matter is, as far as your home electronic equipment is concerned, the power line 'starts' at the transformer out on the pole outside your house. This is the local low impedance source of the 240/120V power that enters the home, and thus, is the real beginning of the AC power line circuit.
For more on power cords and AC power issues, see:
http://www.audioasylum.com/audio/cables/messages/82423.html
and all the previous posts it references.That is, if you really want something reasonable to think about.
Jon Risch
Follow Ups:
"the power line 'starts' at the transformer out on the pole outside your house. This is the local low impedance source of the 240/120V power that enters the home, and thus, is the real beginning of the AC power line circuit"Well, this is still arguable, but I think it's a darned fine point to start modelling...
If you dissect this circuit, from the secondary winding of this transformer, you get the following components involved:
-Secondary winding to O/H line connections (marrettes? crimp? terminals?)
-O/H line to Service Mast (wires twisted on steel guy wire)
-Service mast to wires in conduit (marrettes and tape)
-Wires in conduit to Panel Main Breaker
-Main breaker load side to vertical panel bus connection (bolted?)
-Panel vertical bus to branch circuit breaker line side connection (snap in?)
-Branch circuit breaker terminal to branch circuit conductor (solid wire in a compression screw terminal)
-Branch circuit conductor terminal to branch circuit wiring
-Branch circuit wiring to wall outlet terminals.Now... if series inductance is the "killer" of quality audio, I want to know what the series inductance of the O/H lines, wire in conduit, and branch circuit wiring is.
I also want to know why a cheap and dirty 15A rated contact in a $5 circuit breaker that is "plugged in" to a $100 panelboard is okay but a receptacle on a branch circuit from this very panel needs to be an oyanide cryo'd high-pull-out-resistance audiophile grade receptacle costing $200?
WHY ALWAYS STOP AT THE WALL OUTLET IF CABLE IS MISSION CRITICAL?!?!
The only thing that I think needs further investigation are claims that special "audiophile grade AC cables" do indeed reduce "conductive RFI" or a cable resonance. (say 25MHz for arguments sake).
But before THIS question can be answered, I would need more proof that this resonance is going to a)result in more RFI being conducted or induced in the components PSU which b)can get PAST the filtering in the PSU and c)cause audible deleterious effects to the audio signal if they even get that far. And even then, I wonder why ONLY THE AC CORD IS A BIG BAD RESONATING THING and why house wiring and wiring back to the transformer is never addressed. I also wonder why the AC cord is thought of as a component, when in fact, the entire current loop from transformer to transformer should be examined, either as a model, or a bunch of "components" in series. How can only the last 6 FEET of cable be "not good enough"? What about the other 100 feet and three other wiring methods that are NOT even CLOSE to being as good as even a $5 serpentine service cord for RFI rejection and inductance? Not to mention the two breakers and how they connect to the panel bus...
It this because expense for lavish cables is okay but thought and effort is out of the question?? I suppose ANYBODY can upgrade AC cords - and do not need an electrician to do this...
(((I THINK SO!!)))
There is a huge difference between "miles and miles" and a hundred feet (or less). Miles and miles turns off the brain, it just can't matter, etc.Of course, you chose to still try to make out the "6 feet" as insiginficant, while all the other arguments and measurement info I posted in the reference material is still true.
Folks should read the cited posts and web pages, and see for thermselves what you have glossed over so casually.
Jon:Not really. I am moreso suggesting that if things like trapping RFI, keeping out EMI, and minimizing inductance is important (and let's say they all are for the sake of this post) then why is it the 6 foot cord that gets the most attention? Is it the worst cable method of all the ones in place? Or just the most convenient one to experiment with, as I suggested?
Keeping out EMI is a no-brainer. Even with proper grounding, why put 60Hz fields near signal sources?
RFI resonances *do* appear to have merit from an engineering standpoint (transmission line theory), but you said something in that article that caught my eye:
"Reduced levels of induced RFI and radiated EMI/hum fields would not hurt SOTA sound reproduction."
Okay, these guys (Sean and J. Neutron) are differentiating between induced and conducted RFI, and there are different bandwidths for those kinds of interference. But your statement makes me wonder. Do we do things in audio beacuse they won't hurt? Or because they actually help? I can do 1,000,000 things that don't hurt - but they're all FREE! I don't think doing things simply to be "on the safe side" is good engineering, and it opens the door for products that "might do something" that we all need to use - to be safe.
I've read soooooo much about cable theory in the past few days I truthfully need to give your article a much better read. (There is a lot there to process Jon). I just liked your concept of what constitutes a "sane model" for looking at this. I do plan to read and digest as many references as I can. The theory alone here is not for the faint of mathmatical heart!
But you must admit: building the "perfect cable" that rejects RFI is amazing. But putting it in the same circuit as wiring that could very well be an "RFI magnet" (and inductive nightmare) does not make sense to me.
And we all know of quite of few guys who put special wiring back to the panel (and even better quality breakers) when renovating or building custom audio rooms.
So? Are these guys on the right track? Or did they just need a better AC cord or two? A couple grand for two good AC cables compared to tearing into walls? I can see the attraction and empathize.
Cheers,
Presto
It is undoubtedly due to changing out an IEC connected power cord is a lot easier than ripping the wires out of your walls, and having a high priced electrician come in and put some other wiring in there.Ever try to work with a local electrician, and ask them to install some high performance wall wiring? Unless it looks just like Romex, they freak out and won't do it.
Going from typical Romex to a shielded heavy duty wiring run is not a trivial expence, especially if you literally have to rip out the walls to do it. Unfortunately, the major expense comes in from repairing/replacing the walls!
Of course, it would make a lot of sense to have superior wiring put in place from the transformer, to the breaker panel and so on. But there are limits to what the average consumer can do and afford.
In most cases, even replacing the breaker panel is a major pain in the behind and wallet, in some locations, unless the panel burned up and is no longer functional, you literally CAN NOT replace it, it is against some local ordinance.
Then of course, there are people in rented houses, apartments, condos, etc.
So dealing with the line cord is indeed the easiest way to try to control the AC power situation. Note that the power cord is the closest thing to the audio components in most cases, while the wall wiring is spaced well away from all the components and cables.
Note that I do not advocate spending $2000 plus on an AC power cord, hence my DIY recipes and recommendations (I believe that I almost single-handedly made the Volex/Belden pre-moulded power cords as an aftermarket replacement, a popular alternative).
Also see:
http://www.audioasylum.com/audio/cables/messages/123367.html
and my two replies, especially the last at:
http://www.audioasylum.com/audio/cables/messages/123437.htmlYou might find those posts interesting.
nt
Interesting John. Just a question: Are you saying then that in general the improvement of going to a premium power cord for Class A devices is negligible (ignoring sheilding for a moment)?
Even in terms of JUST current delivery, not negligible, just a lot less than for Class AB power amps.Note that the crappy connections of the pre-moled cords are still there,the overall resistance of a given pre-moulded cord is still much higher than the high performance cord that is hand wired, etc. Then throw in the shielding, any EMI/RFI filtering, etc.
This post is made possible by the generous support of people like you and our sponsors: