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Nordost Valhalla AC Power Cables, I've been reading a lot about them...
jaustin
post Aug 4 2004, 20:41
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QUOTE (useless_engineer @ Aug 4 2004, 12:14 PM)
the reality of the matter is that they _all_ buy their cables pre-made from a number of asian manufacturing conglomerates from basically a catalog.
*

Most. Not all.

Jim
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useless_engineer
post Aug 4 2004, 21:04
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Power delivery systems (in the U.S.) are designed to deliver 120 V A/C TO THE RECEPTACLE at the full rated power. Typical house wiring is 12 or 14 gauge. The typical power cord is 18 gauge. Currents drawn by an amplifier during the re-charging of the power supply can reach values that are 10-15 times larger than the RMS value.  That can mean significant voltage drops in those 18 gauge power cords, perhaps 5 Volts, OVER THE LENGTH OF THE POWER CORD. Yes, there will be voltage drops in the household wiring, too. But they will be smaller if the wiring is up to code.


I agree...but I wasn't really referring to the voltage drop across the cord (or the household wiring, or the transmission line wiring), but interference inducted into the cord, which is the main advertising feature of these cables. Even whether they are even recieving the full rated 120V usually is not a consideration to those buying these cables...it's whether they are getting a perfect 60Hz signal that interests them (which as stated above is rather irrelevant once the power supply converts it to DC). Basically, more noise is going to be inducted into the unshielded household wiring on the way to the local transformer than there ever will be from the socket to the component was my point. A thicker gauge power cord is definetly warranted if you believe an amplifer comes with an insufficient gauge... but someone who buys a $2500 power cable I assume is probally running a $10,000+ amp which I sure hope would come with a measily power cord whose internal resistance is within design spec.

QUOTE
Most. Not all.


Yes, I was generalising a bit. But even then, wires which aren't made overseas are still made from the same extrusion processes, the materials are obtained from the same suppliers and the cost is comparable, usually a bit higher.

This post has been edited by useless_engineer: Aug 4 2004, 21:10
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jaustin
post Aug 4 2004, 21:50
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QUOTE (useless_engineer @ Aug 4 2004, 03:04 PM)
Even whether they are even recieving the full rated 120V usually is not a consideration to those buying these cables...it's whether they are getting a perfect 60Hz signal that interests them (which as stated above is rather irrelevant once the power supply converts it to DC).

Now THAT'S asking a lot of a measly power cord. You can filter out all the RF muck you want to, but you aren't going to be able to restore the shape of a typical distorted, flat-topped 60 Hz signal. For about the same as that $2500, however, you can buy an A/C power regenerator--basically an amplifier optimized to produce a single frequency--that'll give you a more or less perfect signal. Then again, most of the folks who buy the $2500 power cords already have those.

QUOTE
Basically, more noise is going to be inducted into the unshielded household wiring on the way to the local transformer than there ever will be from the socket to the component was my point.
*


That's what filtration is for (or regeneration). I think the combination of filtration and shielding makes for a sensible conservative design: filter out the noise that gets in in the wall, sheild it once it's passed the wall. Also: One thing that's been mostly left out of this discussion so far is the noise generated by the components themselves. Digital components can generate all sorts of nasties that, if unfiltered, can get back into the household wiring. Filtered A/C cords work both ways. I can't verify it (or prove it) but I wonder if a ferrite-impregnated power cord couldn't even, perhaps, reduce high-frequency radiation by slowing down high-frequency transients. Pure speculation (I can do that as long as it's not about what I hear, right?).

Cheers,
Jim
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Pio2001
post Aug 5 2004, 00:32
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QUOTE (jaustin @ Aug 4 2004, 08:41 PM)
QUOTE (useless_engineer @ Aug 4 2004, 12:14 PM)
the reality of the matter is that they _all_ buy their cables pre-made from a number of asian manufacturing conglomerates from basically a catalog.
*

Most. Not all.

Jim
*



Incredible but true, the French company Hi-Fi cābles advertises the superiority of their Made In France Cābles shamelessly relying on obscure and pseudo-scientific theories claiming the racial superiority of french people hearing over asian people hearing ! sick.gif
The text is available in French only : http://www.hifi-cables.com/04_03.html

QUOTE (jaustin @ Aug 4 2004, 08:40 PM)
I'll close by not making any claims about the positive effects I might (or might not) have heard when I switched out my Belden 14 gauge shielded for a budget hi-end power cord (which cost about 5% what the cord being discussed here costs). I won't make any claims because to do so would violate TOS8.
*


Well, since you tell that it would violate TOS 8, maybe this is because you think that you can hear a difference. If you have the occasion to setup a blind listening test between two power cables that sound different to you, we would be inhterested to know the result.
It would also be interesting to run an RMAA analysis, if you can, on a device fed by different power cables, if it can show a difference in the background noise, for example.
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jaustin
post Aug 5 2004, 02:09
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QUOTE (Pio2001 @ Aug 4 2004, 06:32 PM)
If you have the occasion to setup a blind listening test between two power cables that sound different to you, we would be inhterested to know the result.
It would also be interesting to run an RMAA analysis, if you can, on a device fed by different power cables, if it can show a difference in the background noise, for example.
*

I have some ideas for doing something along those lines. For me, though, this is a hobby, and finding the time is always a struggle. But, given that no one (that I've ever heard of) has done such a thing, I'm sure it'd be worth it.

Cheers,
Jim
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ara-fat32
post Aug 5 2004, 05:10
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Hi-fi Magazine Rules, why they can find peoples pay 2500$ for a Cable.


If you working for a HI-Fi Magazine, you need to travel around many miles, most of Hi-Fi manufacturers invite the reporters to an luxuriosy Hotel or whatsoever Sweet, don't ask why.

If you read a Article about a better Power Wiring, you should keep minded that this cables only are worth the copper inside, and PVC.
But some idiots believe to this stupid Hi-Fi Magazines just because a single idiot gets invited by a Hi-Fi Manufacturer to an Luxuriosy Hotel or whatsoever Sweet,
now, you know why.

Forget all those deep s**t Amp Racks, Get a Beton Rack and a few Rubber sticks from 3M or China it does it always.

Forget this ultra expensive Speaker Wires, & terminals

And last but not least:
Forget those clowns from Hi-Fi magazines.
And don't forget this message.
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useless_engineer
post Aug 5 2004, 05:45
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QUOTE
but I wonder if a ferrite-impregnated power cord couldn't even, perhaps, reduce high-frequency radiation by slowing down high-frequency transients.


Slowing down high frequency transients?!? I'm not trying to be rude...but was this supposed to make any sense?
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jamesattufts
post Aug 5 2004, 08:24
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Would the whole John Dunlavy debunking of expensive speaker cables apply to power cables too? I'm inclined to think they would be even less critical as most houses aren't wired with 1400-dollar interconnects, nor are the components the cable plugs into. Someone should convince Paul Allen or the sultan of brunei to run stereophile magzine-recommended cabling back to the power company.
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2Bdecided
post Aug 5 2004, 09:33
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QUOTE (Xenno @ Aug 4 2004, 03:12 PM)
Yeah...whatever. You'll either hear it...or you won't. I don't care what you turn yours up to...or what anyone else turns theirs up to...they'll either hear it...or they won't. Read the thread title again so that we're on the same page, because in my previous post I state the conditions where these cables may be useful. It would be highly unlikely that the dimunitive effect of a properly run standard power cord would push humm (and other forms of interference) into the audible range (even when compounded by xxx number of cords). Theoretical?..forget about it...I speak from practical real world experience.
*


I wasn't answering the original post - I have no desire to defend $2500 power cables.

I was specifically criticising your blanket statement things are either black or white, you can either hear it or you can't.

Human hearing is stochastic, not deterministic. Even the masking threshold data at the heart of psychoacoustic codecs are probability thresholds (e.g. 50% chance or 70.7% chance of hearing something), not absolute thresholds (now you hear it, now you don't).

If you were only referring to the power cables in question, that's fair enough - but to suggest that every audio component can be judged with a black or white "this makes a difference" vs "this doesn't" doesn't make any sense. If that's not what you meant, then ignore my comments. If it is what you meant, then I strongly disagree!

Cheers,
David.
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rickshaw
post Aug 5 2004, 09:46
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There is a rule of thumb in Hi-End Audio that you should expect to spend 10-15% of your total system value on interconnects, speaker wire and power cords.

With this in mind power cords that retail for $2500 would not be out of line if you have a $50,000 system....and yes many people do spend that much. It is common to see amps (mono blocks) go for $15,000 or 20,000 with preamps costing about half that. Speakers.....how much do ya got? It can cost as much as your car...or more.

Bottom line, don't knock what you have not heard. If your perspective is a amp wired with "bell wire" or a sound card and PC speakers you need to understand there is a whole new and expensive world out there.

Would I spend $2500 on a power cable?? No, but I will and did do a DYI and spent $75 doing so. Sound to me, in my system, using my ears, with my music and my gear is better than the stock 18 ga cord that came with one of my components .

As mentioned in earlier posts, there in no B&W on this issue and the improvement is very subjective.

Just hope and pray that some day you can afford to and not think twice about spending $2500 on a line cord. smile.gif

Peace,

sdz

This post has been edited by rickshaw: Aug 5 2004, 09:53


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Pio2001
post Aug 5 2004, 12:02
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QUOTE (rickshaw @ Aug 5 2004, 09:46 AM)
Just hope and pray that some day you can afford to and not think twice about spending $2500 on a line cord. smile.gif
*


One should first demonstrate that they have a different sound than regular power cable before this is advised in this board.
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rickshaw
post Aug 5 2004, 12:45
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Pio2001,

As mentioned the issue at hand and the impact these power cords have is in my opinion subjective at best. In my experience upgrading power cords has made a improvement in the audio quality on MY system to MY ears. I need not prove anything to anyone.

This is exactly like proving there is a God. I and others believe in one yet there are some out there that don't and still others that want proof.

There are many in the audio world that feel power cords and interconnect upgrades are worth the cost. They need not prove anything to you, me or anyone else. It is their money, their systems and their ears.

Here is a link to a group that would beg to differ on the value issue and if you care to read you will find what you search for:

http://www.audioasylum.com/audio/cables/bbs.html

There is a simple solution, don't buy them if you feel they are of no value. smile.gif

Peace,

sdz


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Somebody has to do something, and it's just incredibly pathetic that it has to be us. Jerry Garcia-Grateful Dead
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jaustin
post Aug 5 2004, 13:18
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QUOTE (useless_engineer @ Aug 4 2004, 11:45 PM)
Slowing down high frequency transients?!?  I'm not trying to be rude...but was this supposed to make any sense?
*

Yes, it was. And as a useless physicist, I'll be proud to display my useless credentials beside those of any useless engineer. tongue.gif

What it means (and I admit it might not have been clearly expressed) is that the instantaneous (or nearly so) demand for current that results from digital switching could not be immediately met, because the rise time of the current in the filtered power cord is slower than the PS would otherwise require in recharging. Very rapid changes in current result in noise. By slowing down the rise time, you reduce the noise. Pretty straightforward.

Cheers,
Jim
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.halverhahn
post Aug 5 2004, 13:49
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QUOTE (Funkstar De Luxe @ Aug 3 2004, 07:56 PM)
Can some one please tell me a logical/scientific explanation of how this works?  Is there one?  Anyone actually heard the difference a good power cord caqn make to their system?  It seems like a load of shit to me but there is just too many reviews and publicity for it to be completely false.


It works because it's voodoo... and the reviewer is bribed.


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Gecko
post Aug 5 2004, 15:39
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I have a related question. What kind of power cables are used on expensive, highly sensitive laboratory equipment? I'm thinking of raster tunnel microscopes or similar stuff. Considering the amount of money spent on such equipment, spending an additional $2500 on a power cord would be peanuts.

I don't actually know the answer, but I would strongly assume it's just your everyday cord (shielded perhaps). I suppose, if super expensive, specially designed power cords were beneficial, laboratory equipment would reveal it (higher resolution/speed or whatever).

Also consider the Pentium 4 CPU which is extremely demanding of the power source because of very rapidly changing load and very low tolerances regarding power stability. And yet there aren't any special oxygen free, yadda yadda cables used in your PC. The legs of the capacitors, resistors and coils are just standard. Miraculously it still works.
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DigitalMan
post Aug 5 2004, 16:25
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QUOTE (rickshaw @ Aug 5 2004, 03:45 AM)
Pio2001,

As mentioned the issue at hand and the impact these power cords have is in my opinion subjective at best.  In my experience upgrading power cords has made a improvement in the audio quality on MY system to MY ears.  I need not prove anything to anyone.

This is exactly like proving there is a God.  I and others believe in one yet there are some out there that don't and still others that want proof.

There are many in the audio world that feel power cords and interconnect upgrades are worth the cost.  They need not prove anything to you, me or anyone else.  It is their money, their systems and their ears.

Here is a link to a group that would beg to differ on the  value issue and if you care to read you will find what you search for:

http://www.audioasylum.com/audio/cables/bbs.html

There is a simple solution, don't buy them if you feel they are of no value. smile.gif

Peace,

sdz
*


The analogy to God is inappropriate - please do not go there.

The reason you have to prove that you can hear a difference in cables is because of the rules of this forum (TOS 8). Search for numerous threads documenting the placebo effect of audible claims - it is an extremely powerful and potentially expensive psychological effect. If you claim on this forum that something makes an audible difference then you need to show proof, otherwise don't post it and enjoy the audio placebos and fetishes in private.


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Was that a 1 or a 0?
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useless_engineer
post Aug 5 2004, 16:51
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QUOTE
What it means (and I admit it might not have been clearly expressed) is that the instantaneous (or nearly so) demand for current that results from digital switching could not be immediately met, because the rise time of the current in the filtered power cord is slower than the PS would otherwise require in recharging. Very rapid changes in current result in noise. By slowing down the rise time, you reduce the noise. Pretty straightforward.



Now that makes sense smile.gif The other post was worded like you were trying to 'slow' frequency. Although I have to say I'm having a hard time imagining a common amplifier with enough peak output capacity for this to be an issue...discharging the power supply capacitors faster than they can be recharged means implies you are overdriving the amp well beyond it's RMS design power and the distortion you get from this is going to be several orders of a magnitude greater than that of the filtered power wire.

QUOTE
I have a related question. What kind of power cables are used on expensive, highly sensitive laboratory equipment? I'm thinking of raster tunnel microscopes or similar stuff. Considering the amount of money spent on such equipment, spending an additional $2500 on a power cord would be peanuts.


The design of power cables for most lab equipment is fairly generic, they tend to be a slightly thicker and have decent shielding, but not considerably different than you'll find on say a decent computer screen. Ocassionally they are twisted pair (where the signal and ground wires are closely spiraled such that interference in one wire cancels interference in the other). Generally the noise reduction of the power lines is the job of the power supply...but needless to say your going to find a far higher quality power cord than lamp cable. Keep in mind that higher quality probally means the cord cost $5 as opposed to $1.

Most of the time the main concerns are grounding and the interconnects used between sensors and the measuring device. Typrically care is taken such that the chassis of the powersupply, amplifier, measuring device (say an oscilloscope) ect... as well as the shieldind on the interconnects, are all attached to a common ground (using sufficient gauge wire to minimize resisance differences).

The interconnects themselves are usually (but not always) twisted par with a metal shield. (like decent audio interconnects, decent meaning $30 radio shack cable - not kimber cable). The resistive, capacitance, inductance values are important here because they create a bandpass filter in the wire. This is true for audio cables as well, but is a fairly non-existant problem with a decent cable which will handle signals fine well past 100,000 Hz. It's far more important for something like an oscilloscope which may be asked to measure into the gHz range. For more difficult signals differential cables are sometimes used (like pro-audio XLR balanced cables) which used a differential error signal to cancel out induced noise or a sensor with a high output level (say 10V instead of 10mV...as 0.01V of induced noise would be insignificant at 10V vs. very bad at 10mV) or current loop transmission (signal is encoded by varying the current at a more or less constant voltage). I should also point out that the quality of the interconnect required to reduce noise is directly proportional to wire length...so you want to keep runs as short as possible. If your going to try and run an RCA cable 100ft you're going to need a much higher quality cable... but from 3-6ft like you should be using (and digital coax or optical for larger runs) the luxary cable's possible improvement should round to zero (this applies strongly to signal cables, much much much less so to power or speaker cables).

$2500 would be peanuts for some equipment, but you have to keep in mind that the goal of the engineer designing this equipment is to meet a maximum signal quality level at a minimum price, and they are going to do this by analysing the signal path in a repeatable, measureable, scientific manner. They will not rely on marketting gibberish or unproven subjective opinion. So unless he/she can prove such exotic cable is absolutely necessary it will not be used. The fact that super-luxury audio interconnects are NOT used for applications which require considerably more accuracy than the human ear will ever be capable of resolving should say enough.

This post has been edited by useless_engineer: Aug 5 2004, 17:49
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cabbagerat
post Aug 5 2004, 17:51
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QUOTE (jaustin @ Aug 5 2004, 04:18 AM)
QUOTE (useless_engineer @ Aug 4 2004, 11:45 PM)
Slowing down high frequency transients?!?  I'm not trying to be rude...but was this supposed to make any sense?
*

Yes, it was. And as a useless physicist, I'll be proud to display my useless credentials beside those of any useless engineer. tongue.gif

What it means (and I admit it might not have been clearly expressed) is that the instantaneous (or nearly so) demand for current that results from digital switching could not be immediately met, because the rise time of the current in the filtered power cord is slower than the PS would otherwise require in recharging. Very rapid changes in current result in noise. By slowing down the rise time, you reduce the noise. Pretty straightforward.

Cheers,
Jim
*



That's the job of the filter caps in the power supply. Generally a good PS for a domestic amp will have some large capacitors to remove 50Hz (or 60Hz) ripple from the rectifier (10mF per channel is what I would chose for a 60W amp). Because big electrolytics have a large Equivalent Series Resistance and series Inductance, they don't filter out high frequency (over 500Hz) low amplitude (say 30dB below the main 50Hz component) very well, if at all. To solve this problem, a set of smaller film or ceramic caps are put in parallel with the filter capacitors (generally a couple of nanofarads). While this sort of first order RC filter doesn't produce pure DC, the Power Supply Rejection Ratio of the amplifier means that noise from power supply ripple is around -100dB. You'll be able to hear it only if you really crank the volume with no signal.

Generally the current demands for digital switching will be taken up by either the decoupling caps on the board. A little noise is the least of your problems if you let your rail voltage drop heavily when a switch occurs.


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dreamliner77
post Aug 5 2004, 19:17
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I bet we could sell some of these $2500 cables to the Pentagon....


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"You can fight without ever winning, but never win without a fight." Neil Peart 'Resist'
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2Bdecided
post Aug 9 2004, 12:41
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QUOTE (dreamliner77 @ Aug 5 2004, 06:17 PM)
I bet we could sell some of these $2500 cables to the Pentagon....
*


Weapons of mass delusion?

Sorry - I'll get my coat...

Cheers,
David.
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