Power cords - do they really make a difference, other than potentially reduce noise?

FrantzM said:

Jack

Impulse response suppose ALL frequencies possible from DC to infinity .. The device under test will naturally act as filter ...
It remains possible however to use an STFT or any FFT algorithm to analyze the impulse response and thus deliver a CSD plot from it .. In electronics that may not be too useful for transducers it indeed is..

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That's precisely what I'd like to see done Frantz, but I would like to stress all frequencies simultaneously. Doing one frequency at a time then assembling the results into a plot would defeat the purpose of the test which is to see if there are frequencies attenuated as the duration of the pulses increases. Should some frequencies spike then it would be reasonable to suspect IM or other types of distortion acting like the referred pain of a headache. Now if impulse response does suppose all frequencies from DC to infinity, I'd really like to see this twist applied to it. Change up the impulse durations and amplitudes, mimicking a music signal.

In any case I think it would be a good way to test any part of the power supply. It just so happens that in this case, the variable is the power cord. The reason I'm thinking white and pink noise in pulses is that it is orders in magnitude closer to music signals than pure tones.

Jack

For a power cord that does not seem necessary unless it is a filter and few are if any... The goal would be to prevent antyhing but 60 Hz to reach the power supply. A steep pass band filter can do it and would be relatively easy but rather big depending on the power rating of the componet to be powered. There are much better way to accomplish this, which is Power conditioning..
THis is what I alluded to , trying to kill a mosquito with an army tank....and you know where I stand on the issue already

Also a power cord has to deal with only one frequency and it is supposed to be like a test tone ... continuous .. that is what good AC do 60 Hz and 120 V in the USA from when you turn it on to when you turn it off ... 220 , 50 Hz in Europe and other places ...A PC is not being fed music rather one tone all the time ...
It remains that if you think you heard differences and enjoy them ..as Raul would say, Enjoy the music .. I am simply noting that careful auditions with knowledge removed may yield a more ordinary outcome..

Frantz,

That is what it is supposed to do. Again, respectfully, I am not debating your position. I am thinking out loud about how one might answer the original question which is the title of this thread. I am saying that such a test might show if not just the power cord but any part of the power supply be it a resistor, diode, capacitor or even hook up wire could impact the audio circuit's sonics. Within this broadened context, I really don't see it as a Mosquito/Abrams situation. The test is not on the cord but on the amplifier. The cord just happens to be one of the easily considered variables. Given the current set of metrics for quality control, none to my knowledge have ever mapped out performance under dynamic conditions. Very different from say the automotive and aeronautics industries where say engines are mapped out with factors such as air pressure and temperature and aerodynamics are subjected to varying velocities and directions. All I've seen from the audio industry are averages at static conditions or very few full bandwidth conditions but with limited predetermined amplitudes and limited durations.

By introducing frequency and duration all we're doing is filling in the blanks but again a composite of tones do not a real world test make. Like air velocity and direction for a wing, an amplifier must deal with ever changing conditions represented by the loudspeaker's back emf. We already know what the benefits of a stiff power supply are. We already know that subjectively some people prefer underdamping rather than optimum or maximum possible driver control. What we'd be doing is mapping out performance in the frequency and amplitude/time domain. For example, we might be able to see not just at what power output thermal distortion begins to set in but exactly what frequencies are impacted. Such data could be very useful for a designer.

Going back to the power cord, the very same argument is used against speaker cable. Even you prescribe that at 6gauge all things are equal. At least you have a standard, a rather high one since 6 guage is not exactly in stock like 14 gauge is. Now supposing such a test carried out independently proves that 5 feet does change performance in the audio circuit that it feeds, could the methodology and results not lead to the design and construction of a low cost power cable that has minimum impact on an audio circuit? I say why not? Could this, if it even works at all, not bring down r&d costs that will ultimately benefit the consumer? If so then again why not? Dynamic testing has kept us in the air. That it turns out that they forgot to fire 300mph frozen chickens into engines and cockpits with a cannons to avert the consequences of bird strikes, is beside the point!

I say why not keep an open mind about things. To lighten things up a bit, if an archeologist found the fossils of a modern cow in rock strata with an age that no cow had supposedly existed yet, the immediate reaction of the scientific community would be that it was a hoax. Conspiracy theorists would say that the U.S. Government has a time machine recovered from the crash at Area 51. Cultists would say that indeed Cows are holy and that it is a sign that the world is ending. A real scientist however would not be dismissive but rather would try and find out simply how that cow got there despite being able to trick all the dating protocols. If all goes well, the world ends up with an even more accurate dating method if not, conspiracy theorists and cultists will unite saying that the US Government has a time machine and has been transporting holy cows into the past to avert the end of the world. Meanwhile, the scientific community will put the remains of 3 million year old bessie in a drawer never to be seen again probably to hide the fact that either darwin was wrong or a farm hand got the better of them.

I don't think I'm being unreasonable. I gave a simple, highly possible, potentially useful, practical and impartial way to answer the question. Some apparent evidence of that impartiality is I'm getting it from both sides of the fence.

Let's agree that the position is somewhat academic. The order of magnitude in deriving a waterfall for a passive component as simple as a Power cable may require at Audio Freq. would be so minute as to require a 10 foot screen to analyze but one can always soldier on.. My point remains the following. The role of the PC is to simply not to be in the way .. a simple conduit for the electrons to come across ... One already knows what the frequency has to be, let's suppose that one also knows that other frequencies are there (one Always should suppose so) what are the solutions? Not much: fiter the wrong frequencies out and leave the 50 or 60Hz only This is power conditioning and as I have mentioned in my previous posts remain relatively easy to do but at the premium of size since what is needed is a pass-band filter for a low frequency and rather substantial power in the case of a powerful amplifier .. That is all there is to it ..
One can always measure a person to a sub-atomic precision and a given 2 meter person might actually be at 25 celsius, at sea level at the equator 1.99860016785789 meters .. The person remains a tall 2 meter human being for ALL practical purposes ... similar fine analysis of such a simple passive component does seem unwarranted IMHO ... a simple, open minded knowledge removed audition would tell you quite a bit ... Thus my Mosquito /abrams comparison

We can always complicate things .. At the end truth is always much simpler ... PC ..If you enjoy finding he "huge" differences they make .. By all means do .. but ... the differences between competent power cords, those of enough gauge and clearly correct construction for a given component power draw are so small as to be inaudible... Same with speaker cable .. You have a fine system do try the Knowledge removed experience yourself with a few friends .... You will be edified ...

JackD201 said:

...It just so happens that in this case, the variable is the power cord. The reason I'm thinking white and pink noise in pulses is that it is orders in magnitude closer to music signals than pure tones.

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I agree with you. Just wanted to point out that pink or white noise is uncorrelated whereas music is correlated. I have always wonder whether square waves swept through different frequencies might be better.

Also, may I re-propose again the following idea: Put music through the system and compare the input (known exactly from the input file if it is digital) to a measurement of the output sound. The ratio should be a constant if the system and room are perfect. But, of course it won't be. So, now chase down the difference.

Frantz,

And my point is that the test is not limited in utility to power cords, such a test however might show that there may be more to the cause and effect relationships between components in the same circuit precisely because present test's output data are not geared to directly correlate with what might be audible to begin with the way a waterfall does. They are geared for standardized metrics used to determine quite basic operating parameters that only scratch the surface of what amps do. In other words they can tell you that they work and to a certain degree how well they work under stresses for safety reasons but not how they might sound. That is unless you are like that other guy who thinks todays present test methodologies can explain everything and do it completely to boot.

Let's leave blind testing out of this though. If you want to subscribe to that as the only test that matters for you and think that it can be a substitute for any other, go right ahead too and enjoy your edified life. Which makes me wonder why you are interested in this thread at all unless you are preaching "The Way". Why not tell the thread starter to just do what you did and be done with it? Like I said, it isn't all that important to me but that doesn't mean I can't be curious about the fact that I and many others hear it but have no real explanation for it. I would gladly take it for what it is without "complicating" things if there just weren't so many guys like yourself who walk and talk like I and others like me are simply delusional and take every opportunity to stick it in there by resorting to the "you can't hear it anyway" position.

At the risk of sounding like a broken record............it is the effect of a passive component within the power supply chain on the active circuitry. It is the active circuitry that is amplifying the noise bursts and that is what we get the waterfall of NOT full range noise through the wire of a power cable. The latter I agree would be ludicrous! I don't know what kind of an idiot you think I am if you thought that was what I meant.

I've edited nothing. Please go back and read my posts. Nowhere did I even remotely suggest that the cable itself be measured.


Jack
Definitely writing as a member and not a moderator

Smokester,

Your right. I just can't think of anything that can be consistently used both for quick bursts and extended duration.

Ron Party said:

Mark, so as to bring this interesting thread back OT, given your obvious vast experience in examining and sometimes modifying the guts of a variety of gear in what way can/does a power cord influence sound and, if it does, how would that difference manifest itself?

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In a non-RF polluted environment, it would be unlikely that a power cord would influence the sound (and by that I mean introduce audible levels of hum, buzz, hash or other noise into the audio heard at the speakers). Manipulating the power cord in an RF-polluted environment (when the attached audio gear lacks sufficient RF filtering at the power supply mains connection) can and will likely result in changing levels of hum. VHF pollution from a nearby FM/TV transmitter sounds like 120 cycle buzz when its severe. The orientation of the power cord will affect the amount of interference, in just the same way an antenna, like the old 'rabbit ears' we used to use for televisions, will pick up varying amounts of signal.

In a non-RF polluted environment, the only other situation where a power cord may affect the noise level is in the case of unshielded audio gear and that's usually tube gear with exposed 12AX7s or other high gain low level stages nearby, however, this is unlikely, given that the power transformer on the amp is by far a much larger emitter of EMF. If the power cord is routed near the input tubes, and it's not shielded, some hum may be heard, because of the EMF radiated by the power cord itself. If the cord doesn't pass near the input tubes, then it makes no difference. Thousands of feet of cheap aluminum wire powers your amplifiers. Changing the last six feet won't make much of a difference, except in the case of it acting like a VHF antenna in RF polluted environments (because the wire has a relatively high RF impedance and because the wavelengths are about the same as the length of the power cord, typically.

On a power amp, the important function of the power cord is to deliver enough current so that the AC voltage doesn't sag below the amp's minimum operating line voltage when the amp is driven to full power into a load.

There's no 'magical' function to the power cord that is somehow altered by introducing noble metals, or elaborate jacket material, or by cryogenically freezing parts of the cable/connectors. All that AC gets converted to DC in the power supply, and the 'sound' of that AC is muted. All of this assumes that the amplifier itself is reasonably shielded, has reasonable RFI/EMI filtration in its power supply, and that the environment isn't noisy.

I've got electronic light dimmers throughout my house. I also have CFL lamps on some of these dimmers, which is the ultimate in hash. Under my previous stock preamp configuration, the buzz and hash from the dimmers was audible in the audio at very low levels. After adding input filtering to my preamp's power supply and improving the ground topology of the power supply itself by some rewiring and probing with a scope on the 1mV/div range, the trash coming down the line no longer produces audible buzz/hash in the system. Fance power cords would not have helped in this situation. But proper power supply filtration did.

JackD201

Hated debates seem to bring the heat in people. There are many things you accuse me of. Amongst them the inference in your own personal cognitive abilities. Far from me was the intention to question your intelligence. I simply suggested that for the subject at hand, some tests were IMO superfluous which I maintain. I also do think there is a value to a test where the knowledge is removed if the testimony doesn't become different. I don't think that by that I inferred that blind tests were the, your words, only test that matters and think that it can be a substitute for any other, you are wrong. I don't , I simply believe that blind tests do test very well the reliability and repeatability of an observation. I, also believe that long term listening have also their value in choosing what one finally lives with, the biases are however difficult to remove. That is all. I have stated often here and elsewhere that both DBT and Listening tests have their validity .

My last retort to you would be the following. Given sufficiently powerful tools, there are scarcely identical objects. One will discover difference in almost anything and these will be physical, repeatably measurable. That the human physiology , thus mind can perceive them is another thing... We don't see infra red nor do we hear 100 KHz. That was my point. Preaching , I don't need to. My vested interest in this thread and many others is the enjoyment of the hobby at an increasing higher level along with the sheer joy of learning .. I stay away from ad hominem attack they advance neither causes: nor the debate, nor the relationship with my fellow human beings. I will however defend my positions with vigor but respect. I suggest you read my posts too ... I attacked your positions not you, not once you... I am not sure your last post returned me that favor

Frantz,

Your turning this around on me? My so called "position" that you attacked warranted no attack in the first place as it was not a "position" to begin with! In a nutshell it was this

1. I hear differences
2. I categorically stated that I don't know what causes them
3. I presented how I would like to find out

Who are you to tell me that the approach I would like to take is "superfluous" if you and nobody else to my knowledge, and apparently yours, has ever tried it? "Superfluous" despite the potential benefits that might be had OUTSIDE of the power cords. How can an attack on my open expression of curiosity NOT ANY STATEMENTS OF FACT, again not even a "position" per se, be separated from myself?

It's not even a hated debate Frantz. Respect does not include talking down to a peer. That is what brings the heat. How am I to take being talked down to with phrases such as "You will be edified." Now, now Sir, what even makes you think I have not participated in knowledge removed scenarios and presume to know how I fared or might fare. Tell me that this is not a direct attack on my cognitive abilities in an effort to discredit what I think would be at the very least an interesting exercise on no technical grounds other than it being "superfluous" or trivial or not even worthy of attention. Now tell me that that is respectful. Oh I read your posts over and over but it just made it worse.

Do you realize that in all but one of your posts directed to me you made reference to DBT in ALL of them except ONE and the ONE is the one that says what I might find is insignificant? All that despite my saying that I am not debating your position AT ALL. It's like being guarded by Gary Payton or Joe Dumars. I'm not even a player! I'm just a guy thinking out loud making no definitive statements. What the heck are you defending with such vigor without so much as an assailant?

Have the last word man. You could have shot down the methodology, that would have been fine by me. You however did nothing but attempt to trivialize it. That was and is not fine by me.

Jack

MylesBAstor said:

My experience is that AC cords can make a difference - and in some unpredictable ways. For instance, why does inserting a higher quality AC cord between the turntable's speed control and wall make a difference in the table's sound. But damn it does as evidenced by a much lower noise floor.

The caveat is that I don't think one AC cord works in all situations with all systems. So one needs to really be able to compare several cords in their system before plunking down the greenbacks

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I may actually know this one or at least have a plausible theory. Most motor controllers are actually noisy devices and AC power goes both ways. The noise from the controller gets back into your wall circuit and fouls the line. So goes the "theory". Therefore, putting a power cord that reduces noise lowers the noise floor.

This is really cool. I've looked at the viewing stats for this thread and the other thread about "Do Cables Make a Difference" (or something like that) and thousands of people have checked it out. Pretty much every other topic on this site is pretty quiet if not dead by comparison. Everyone is into the question of cables - power or signal - and obviously people are looking for answers.

This may also explain why there are so many cable companies. It's rich territory for cash!

The ironic thing is that I'm pretty sure no one has any universal answers and I'm also pretty sure that this is what people are looking for. I don't know why. I know many local audiophiles in the area and not one of them has the same system. Is it any wonder that everyones experience is different?

No sage advice here or any sermon from the mount however, in my experience they do make a difference. I'd even say they make a bigger difference than signal cables. I find it better, not just different.

Like the signal cables I'm not sure I would ever shout the phrase "night and day". My 1980's vintage cassette Walkman vs my iPod Touch - that's "night and day". I'll still take the perceived percentage improvement with the power cables regardless.

In my system with my ears, yeah, they make a difference.

ack said:

I hope this doesn't turn out to be too controversial a thread, but other than some of them reducing noise (RFI/EMI), I find many after market power cords not materially better than good stock, assuming the right gauge is used in every application. My problem is that I can't scientifically explain the "major" improvements some people claim they hear, unless they are all tied to lower noise and/or marginally better contacts in the plugs.

......

Thoughts?

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I have a sneaking suspicion that every last audible (and real) improvement can ultimately be traced to either an improved efficiency (mechanical vibrations) or lowered resistance (electrical noise).

That would make sense to me since every last system requires these two most basic energies (electrical and mechanical) to even function in the first place. And yet when these two energies are left to themselves (i.e. under-controlled or improperly managed) will utterly cripple every last system's level of musicality. Almost as if a serious performance-limiting governor has been installed.

A system's level of musicality is dependent on how many remaining flaws are audibly degrading what the intrinsic quality of the components are capable of delivering. And most standard components, CD players and amplifiers are not engineered well enough to be unaffected by the quality of the mains power and other interference - playing with the power cord is a way of altering what the circuitry of the piece of equipment is seeing as an "input", via that cord. In the end, it's all just filtering, though the action may seem subtle in nature.

Personally, I just alter standard bits of electrical cable, and where it's plugged in - this gives me sufficient control over that area to minimise degrading effects. The real answer is to make off the shelf audio gear bulletproof to these factors; but this will take some research, and commitment to proper engineering ...

Harlequin said:

http://www.theaudiobeat.com/blog/shunyata_research_medical.htm

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Great article.

Moving this to the measurement forum might force some people to look at:b it.

Gregadd said:

Moving this to the measurement forum might force some people to look at:b it.

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Greg....I did consider starting a thread with the link on that sub-forum, perhaps that would have been the better option.

Harlequin said:

Greg....I did consider starting a thread with the link on that sub-forum, perhaps that would have been the better option.

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Hi Harlequin...i put it under the Shunyata link some time ago...perhaps we could pick it up from there or move mine to yours.

http://www.whatsbestforum.com/showt...Monitor-Noise-Floor&highlight=heart+institute

LL21 said:

Hi Harlequin...i put it under the Shunyata link some time ago...perhaps we could pick it up from there or move mine to yours.

http://www.whatsbestforum.com/showt...Monitor-Noise-Floor&highlight=heart+institute

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Evening Lloyd, I feel that I may have created something of a topical Hydra here in that I re-started a thread in the measurement forum with the link as inseptural post #1, on reflection a mesh, and perhaps Lee or another of the management team might merge/ move my OP to wherever they feel it to be best placed.