i have personally auditioned over 10 different manufacturer's line cords. i hear differences. i don;'t understand how a line cord can affect treble response or bass response.
SpatialKing, Sure that could work too. Do you plan to trigger on the ac-line frequency and run some test signals into a power amp, or do you have some other arrangement in mind. If you have a typical amp and speakers in your lab that would be best of course, to correlate the fluctuations in the musical signal to the changes in current as picked up by your inductive probe.
Please let me know how it goes.
I also agree that BIG expensive power inductors can be used to stretch the charging pulse and therby reduce ripple. It is rare to find this on most amps out there. I think Nelson Pass discusses this very technique on his DIY website devoted to the designs of his Aleph knock-offs.
"Not providing a technical explanation does not by default correlate to fraud. Coca Cola does not share its recipe for Coke, and yet few argue that people enjoy the beverage without having to know the formula."
Coca Cola isn't marketing product based on performance/technical claims that can be verified by the end user. Food companies are not obligated to disclose trade flavor secrets. Two different comparisons.
All of your other audio "electronic" products must meet manufacturer's performance claims, or can be held liable for mis-representation or false advertising. Where is there ANY equivalence to this in audio related "tweaks"? Notice how "vitamin/health food" companies can no longer make health claims?
There should be some agreed upon (and regulated) standards within the industry, just like the rest of your "electronic" components.
Metro04: I was basing my comments on basic power supply engineering. I'll start a new thread on the bandwidth requirements of line cords shortly.
Dpac996: Actually, what you want to use in that experiment is not a differntial probe, but a current probe. This is a device you can clamp on the wire and monitor the current flow through the wire. Tektronix makes several of these types of probes; the basic one with a DC to 50 MHz bandwidth is fine. I plan on doing this in the lab this week, just to see the what the bandwidth is of some cheap basic line cords versus the more expensive ones. I'll post the results in a new thread.
Mrtennis and Tvad: Gee, a cable designer said it makes a difference, so therefore it does. But, he gives no explanation for the reason, no facts, no information based on his own experience in the lab, no experimental data, nothing other than his own opinion, which is what he uses to sell cable at 500 to 2000% markup. If he could sell lots of cable based on opinion, think what hde could do with solid data and facts! What is wrong with this picture? As I have stated numerous times in the past, I am happy to be proven wrong on my opinions, but please, someone show me something other than profitable based opinion that I am wrong.
To all, a general note: Please keep in mind that power supply performance is always improved by adding large inductors in series with the capacitor filters, not by removing inductance. So simply stating that "adding inductance is bad" is wrong. Yes, it can be bad, depending upon where you put it, but let's assume the power supply engineer knows what s/he is doing. After all, you must have some faith in their skills, as you bought their amplifier! Other than cost, and they are expensive, an inductive input L or capacitive input Pi filter, are impossible to beat for power supply filters.
my apologies to all for criticizing others for taking audio matters too seriously, when i am guilty of this myself.
i will try to lighten up and limit the sophistry, but not completely.
trying not to be pedantic, maybe i am, if measurements are taken, and observations are confirmed, one can justifiably have confidence that an event that took place in the past, will take place again. but such confidence is not certainty. without certainty it is not knowledge. most decisions are made based upon confidence of consistency of events.
i recently spoke to a cable designer and he asserts that the metal, dielectric, dampening material, geometry, shielding or the lack thereof, connectors and the connection--solder or other, all affect the performance of a line cord.
i guess there is no definitive answer as to this question.
Dpac996, I'd love to contribute to the objectivist explanations of the PC phenomenon. My only problem is that. . . I am just not at all qualified to do so, except for spotting the occasional attempts to pseudo-science, which, fortunately, I have not detected yet in this thread.
MRT, I am delighted you enjoy my Subalpine attempts to humour. Admittedly, I'd enjoy a therapist very much, except for all accounts payable associated with the service. Last I checked my blood pressure was still nominal. no danger taking myself terribly seriously. . . afraid I never did in the past and likely never will in the future. Similarly, I seem to experience a hard time taking logical sophistry too seriously. I am terribly sorry you feel compelled to offer me a quick funeral service during a court debate. . . in some way though, I feel very honored by the challange, as I am definitely not a legal professional such as yourself, nor The Queen's language is even my mother tongue, nor it is my second language. Would it make you feel truly spiritually fulfilled to do so? Or perhaps you would prefer to reconsider, take a big breath, and try a more convivial, or mayhaps even serenely peripatetic look at the topic at hand and at this virtual community of disembodied souls.
Unfortunately this has turned into a freshmen 101 philosophy discussion.
Can we please stay on topic? please, can we let the pure technical treatment of this question carry forth?
I am one engineer who does not try to reduce the world around me to equations and mechanistic operations. But, in this case I do think there is a technically legitimate answer... This topic is a matter of electrical interaction, nothing else, pure and simple.
This thread is another example of how we audiophiles talk about hearing subtle differences/shadings, sure they are important, but then we rant and rave about this and that being so and the "well if your system, ear, room, etc are not up to resolution " blah blah blah...with no real technical discussion based on facts. It happens and will continue to just be so.
Why such an unwillingness exists to tackle the problem they way it should be dealt with is just lazy.
It's really ok to talk objectively. Objective science and engineering are what brings forth the awesome equipment we love and your music will still sound great to your ears if you choose to bury yourself in the technical details. It's a matter of choice.
Mrtennis essentially states that without proof, there is no knowledge, only opinion. But in the big picture, much of what we all personally consider knowledge is not proven until we too witness and experience if for ourselves.
I "know" that Canberra is the capital of Australia. But how do I really know that Australia even exists? I have not been there. Many people claim it is a continent in the southern hemisphere which I must take as faith. And since I have not witnessed its existence, is my "knowledge" of this indeed not knowledge? In my opinion, Australia exists but I do not know for sure. And even when my plane lands there, how do I still know I am in Australia? My weeklong trek across the Australian desert in a jeep may have in fact been through the California and Nevada deserts. Life is one huge box of faith.
What defines the line between opinion and knowledge and thus fact? Clearly we have a group here that continues to profess that we can not base our knowledge on what we hear. So what do we use to substantiate out claims? Our eyesight? If I alternate between power cables A and B, and repeatedly take measurements through various tests, compare the charts/plots etc., and can visually verify that cable A always has a higher peak than cable B and frequency X, and so on, then can I deduce from these efforts that I now have knowledge that there is truly a difference? But why do I only trust what my eyes tell me and not what my ears told me before? And if it is not a sight vs. sound issue, then it comes down to needing the test equipment to provide the basis for knowledge rather than my own senses.
As I tried to infer before, even when our senses tell us that differences exist, we may be a long ways off from identifying why they do exist. And as an engineer, I too want to know the how and why of everything around me. But this is simply not realistic.
mr g, i will repeat what i said to others. stop taking yourself, the music, the sound so seriously. you resort to argumentum ad hominem instead of critiquing what i say.
your supercilious attitude is one reason why people think an audiophile needs a therapist.
if you lighten up your blood pressure may go down.
i must admit, i enjoy your british humor, it is so biting and civilized, but as a lawyer, i'd bury you in court.
My Friends, If any of my posts came across as arrogant or whatever, I am sorry. I am a music lover and audiophile, but alas, I have a degree in EE. That being said, having an EE degree does not automatically make someone an authority on power supplies and audio amplifiers. There are many paths one can take in this field but designing high performance audio amps, for instance, is a rare path indeed. My job involves digital designs with FPGAs for software radios, but my real passion is the analog stuff.
Although I am in the more objective camp, I have never stated that power cords can not make a difference. Rather, if you follow my previous posts, you can see I made a feeble attempt to describe how such a thing might be so.
One thing that I will never give up is my fundamental belief that if a real change is heard, however subtle, and repeatable, say between one power cord vice another, then there must be an underlying electrical change to manifest such sonic deltas.
If I did not believe this, then it really does boil down to faith in something else.
I do believe that there are material-electrical differences among pcs, and if in the right high resolution system with great acoustics, then these deltas may manifest. I think this can and does get out of hand and folks have to be somewhat realistic about expectations.
The longer I think about this, the more i'm inclined to believe that it's not simply reducible to the large amount of romex, nor the junction box, nor the long lengths from the step down xfrmr on the pole a bazillion feet away, nor the miles of 100 kV lines back to the distribution station. No. It must be the interface to this network. Why/ how I do not know yet but i have some ideas.
I listen to music alot, but I also love to measure things. I love to understand the physics behind something. In my view one reinforces the other.
A basic experiment to test currents on the ac-line: A high power series resistor with the hot lead. The resistance will have to be low and this is not ideal, but it could work. A safe box of some sort will have to house the plugs and power resistor. A basic ocsilloscope with a differential probe across the resistor (do not use the ground clip as you will be connecting the hot directly to ground via the scope cable--not good). A test signal, like some continuous tones ala stereophile cd-2. Of course you need a trigger for the scope. Simply use the 60 hz ac line setting. This way you capture the events you want to see based on the power cycles of the ac.
You plug your amp pc into the thing you fabricated that houses the power resistor. Fire up the amp.
At this point, with the volume low, you might see some activity on the scope that relates to the charging of the filter caps, aka 120 hz (full wave rectifed). If you can trigger the scope just right,and play with the time base, and vertical gain, sample rate, etc i bet if you crank up the input signal you will see, at the peaks, fluctuations that are directly correlated to the amplified signal. Here is where i think power cords can make a difference. The current is pulled sharply from the power amp at these peaks. We know that abrupt changes indicate high frequency. This is direct from theory and confirmation over hundreds of years. (This IS not equal to whatever high frequency content in the signal to be amplified)
This is one fairly simple test that can be run. I currently do not have a working personal scope and probe of reasonable quality. I would love to do this however.
Of course this may be all wrong, but I like to offer possibilites to understanding our beloved hobby.
Better watch out guys and carps, Mr. Tennis's mechanical froggie is loose again in the audio pond with all its juicy and elegant sophistries. Before you know it he'll have you all wrapped around his magical pingponging fingers!
if experience, then induction and opinion. if premises, then logic, deduction and knowledge.
regardless of what is said on this or any other discussion forum based upon experience, it can not be knowledge.
there is a probability that one does or does not hear a difference. the probability is unknown and there is no proof that a difference exists or does not exist.
if 2 people are in a room listening to some component comparison, one may hear a difference and the other not. this disagreemnet does not mean that there is or is not an intrinsic difference between the component. such a statement wwould have to be based upon knowledge and hence certainty.
however knowledge does not apply in that situation.
so, it all boils down to an opinion. a perception is also an opinion. people have different opinions. opinions are neither true nor false.
the purpose of this thread is become apprised of an explanation, more out of curiosity.
what i said about verification is true. there is no definitive verification of a perception. one perception does not confirm another. you can have 1000 perceptions and 1000 stereo systems. there is no way to know what is going on. it is all conjecture and speculation.
it is the exchange of these speculations and conjectures that makes for a lively discussion. it is enteraining and stimulating.
Metro04 - As an educated EE, I clearly do not have the experience today to begin a scientific or engineering investigation on the matter for which you so very much want definitive answers. But I am not sure we are there yet anyway.
As advanced as our semiconductor and software industries have become, they still fall very short of the ear/brain processing to analyze sounds and therefore music. How and where do we even start to develop processes and systems to identify those sonic attributes that the ear and brain immediately tell us what is the real piano, what is a close simulation or what does not come even close? It's not only frequency or phase response analysis. Music is not this simple to quantify. If Mrtennis or anybody else requires these answers to get confirmation that differences do/don't exist, I suspect he is going to be waiting a long time.
Some of the most brilliant engineers are working on the latest developments of digital systems. And the test equipment for these systems has to be even more precise. And yet, in the final analysis, when I hear digital music, as enjoyable as it can be, my brain immediately tells me something is very wrong. Do we have the ability today to measure and quantify this? And if not, how can we expect the industry to provide a solution sheet with all the answers to explain why I can hear that power cable A affects an amplifier differently than power cable B?
There are events when I can not hear differences between some cables in certain links of the chain; this is good news as it leaves money in my pocket. And when there are differences, the more expensive product is not always the one I prefer. Again, good news as it saved me the expense. But there are times when I discover a cable or any other component for that matter that brings on more abc or xyz; it gets me that much closer to the musical performance. It's a win situation in any of these cases.
If we go into the audition with a seeded mind that we will or will not hear a difference, we have to be prepared to accept that the outcome could be different. And this is independent of any survey, poll, testing, etc., done by any other person or group who have documented that cables in fact do or do not make a difference.
I am clearly no self-tauted audiophile. And I am not trying to provide unverified testimonials either. I simply shared my experience that this closed-minded enginner let his ears be the factor vs. a printed technical report to determine that such differences do or do not exist. If one person can hear that differences exist, then they do. And that person could very well be a third party.
As an engineer, I know how easy it is for data to be "presented" in a way that would cause anyone to initially come to any conclusion. And how many of us have access to the facilities to prove or disprove such claims? We rely on others to do this. So this too is all based on faith.
As Mrtennis reported, "hearing is believing, either i hear a difference or i don't hear a difference. at this point it's an anecdotal report which cannot be verified". But Mrtennis, as any of us who are just another citizen of the larger collective, reading a report is believing, and often neither you nor I can verify such. Thank you, but in the case of audio cable differences, I have more faith in my own ears.
With all respect, you being an EE and fully capable of an exact technical explanation for "Mrtennis", why yet hasn't anyone come forword? Just more of the same unverified "personal" testimonial responses we get from every other Agon reply.
As mentioned earlier to "ronniekoh", I've witnessed countless cable blind-testing events where self-touted Audiophiles failed to pick the premium designs over basic configurations during my adult 30-or-so years of HiFi tinkering. This included some of my audio dealer friends who sold exotic cables, as well.
It's not like I haven't paid my dues with personal testing. It went hand-in-hand with my interest in electronics, followed by a professional carreer.
A few others, and myself, attempted to offer an explanation to Mrtennis, and even advised hime to contact as many component manufacturers as needed. Note the sarcasm/derogatory responses directed towards the engineering-minded, yet it was manufacturer's engineering claims that attracted most cable buyers towards their purchase.
Albertporter...I don't wish to argue the merits of exotic power cords, isolation devices, and similar audiophile paraphinalia, but some manufacturers doing demos at shows will admit that they have to incorporate these things in their setup or else their potential customers will not take the demo seriously. Like chicken soup...can't hurt.
It's unfortunate when responses become so emotional and even vicious. As an EE myself, I too lived for many years believing that power cables were minimal at best to not just provide an improvement, but demonstrate a difference between two models. And after trying various power cable models, mainly NBS, PS Audio and Electroglide, I still could hear very little difference compared to "stock" power cables with the Aesthetix Io/Callisto preamp, Manley Ref DAC and CAT JL-3 amps. If anything, these models stand out in their respective classes as having way over-engineered power supplies. The output transformer alone in one CAT JL-3 amp dwarfs the power supply in most power amps. And this has much to do with this amp being the most dynamic amp I have heard by quite a stretch.
The electronics masters who have contributed to this thread would conclude that I did not hear differences because the power supplies here were already engineered to respond or compensate for any differences brought on by different power cables. Such a conclusion would only be due to ignorance as I quickly learned for myself.
After being constantly nagged by two local audiophile buddies, one an architect and another a physician, who said I needed very much to try a power conditioner (PLC) and then follow this with further power cable trials, I took their advice. Was I not the electronics engineer here? What could an architect or physician know about the affects of these products that I could not know? Afterall, I went through all the circuit analysis, power transfer, control systems, amplifier design, etc., courses.
Well in a nutshell, I realized how right they were. With three dedicated circuits for the system, one for each amp and the third for the sources and preamp, at $2k, the Audio Magic PLC brought on more of a refinement in terms of noise reduction and vastly improved resolution that no other component change had ever done in my system. The only unfortunate circumstance about this experience was that I had not listened to these two people sooner.
Two months later they both came over with quite a load of power cables for a shootout in my system. The differences now between power cables were dramatic. I could see them looking at me and silently saying, "I told you so". This long-time closed-minded EE had experienced how significant power cables can affect some of the most impressively designed audio components in the business, and to take the system's performance to levels I had not known were possible with these products.
For me now, I could not care less if someone else out there can not hear a difference in such cables. Their results are due to any number of reasons. But their lack of hearing this only indicates that the cables make no difference in the context of their system. The bottom line is that there are differences and they are often not subtle. If you need to go back and forth over and over to try and hear a difference, then plain and simple, your incoming power is a mess or your system's resolution is just not there yet. And for such a case, put your money elsewhere and repeat the power cable trials every couple years or so. I did, and finally it paid off. Just putting a pair of Purist Dominus power cables on the CAT amps brought explosive dynamic contrasts compared to the other power cables I had here.
As for the response by Mrtennis, "but it can not be verified", oh yes it can. Perhaps not in your system can it be verified, but in the context of many others it certainly can be. So many people in this thread have already concluded the outcome without putting forth the effort to hear the possibilities in a highly resolving and dynamic system. I can relate to such an attitude as I lived it myself on the issue of power cables for many years.
We can believe what we want to believe. And we can preach all we want about what we know due to our experiences and education. But one thing I am very grateful for here on A'gon is the amount of knowledge and experience I have gained by others who were more open minded than I was.....and I was the ultimate beneficiary as they had nothing to gain other than witnessing my happiness from the changes.
Oh and one more thing - do power cables affect frequency response? Go drop a Purist Dominus power cable on your favorite power amp, or DAC or preamp for that matter, and make note of the bottom octave presence and control that was not there before.
Those silly idiots down at Pass, Krell, Levinson, Sim, Wadia, etc. Why haven't they gotten on board with all this vast PC knowledge on Agon?
If you've visited their CES, HE and Euro shows during the last few years, you would find all these guys are using aftermarket high end power cords, interconnects and speaker cables.
Many use aftermarket equipment stands, isolation feet and other accessories as well. Anything to help with the sound.
Why is it always the electronic ignorant that defend their "bat-like" hearing as gospel, and completely ignor the fact that ALL of their audio equipment was "ENGINEERED" based on decades of electronic research. You'd still be beating sticks together if it wasn't for engineering! Those silly idiots down at Pass, Krell, Levinson, Sim, Wadia, etc. Why haven't they gotten on board with all this vast PC knowledge on Agon? But I'm sure YOUR vast knowledge can run circles around their years of combined experience. Speaking of crystal-rubbing, UFO-watchin' "religious types"... Give us a break!
For decades I have experimented and listened for changes in my system. Sometimes I hear something, sometimes I don't. When I hear something I am open minded. When I don't I am a naysayer. C'est la vie.
Unlike power cords, speaker and interconnect cabling can "directly" affect inductive speaker loads, or sensitive gain stages. Both cables are in the audio stream, and can affect frequency response by inductance, resistance, and capacitance. The altering or addition of these passive components may/can be proven audibly (pending their values) instantaneously. A power cord's job is to transfer available voltage/current into the components power supply, thus converted to stable, low ripple DC. This DC will be attained no matter what conductor material is sellected to feed it. Silver or gold conductors will merely grant but a few milivolts difference (over a 6 ft length) into the isolation transformer, over copper. The outlet voltage varies far more at any given moment! Whether being fed by 50 Hz or 60Hz, the power supply converts it into DC, and is un-affected by the passive components mentioned earlier.
Besides all the preceeding footage of non-audiophile Romex wiring, what about all the "acclaimed" aftermarket line conditioners being inserted between the outlet and audio components? Lots of passive/active components in direct contact with the AC stream, thus feeding the exact same audio component. All of which would add way more coloration in comparison to ANY power cord related issues. Oh...and yet ANOTHER power cord! Where's all the "frequency" related questions there? It just doesn't apply to power supplies and cords, with regards to limiting a component's output frequncy. Where's all the concern about the isolation transformer's copper wiring, or core composition? Just think about each and every component's internal soldering, for those bringing up that PC-related topic (includes most power, speaker, and IC cables).
For every personal scenerio you've witnessed/debated someone claiming to hear differenses, I can match with ones who have failed during blind testing, whether in their personal environment, or a dealer's. I've been at this HiFi stuff for three decades now, and been through these discussions/testing before.
My problem is that I lack the discipline with not responding to these forums. Seems no one ever seems to sway the other camp, but in my lengthy career of electronics trouble-shooting and personel training, I've observed all kinds of scenerios where work colleagues report having repaired/diagnosed a problem that wasn't even related, but in fact, they reset or disturbed something else in the process. My explanation/advice to them is to re-verify, sabatage, or replace items they've swapped. More than 70% of the time, they didn't truly fix the problem. That's my advice to you readers. Ignore the label ego and bragging rights, and create engineered methods to reconfirm what you're hearing. That's all...
Reb, you stated: The #1 factor by far is the type of conductor material the cord is built of. Everything else is secondary. Well, I agree but only to a certain point. If I compare my current cable, the Pure Note Paragon Enhanced with another less expensive pure silver conductor cable, I hear very audible differences. The Pure Note is detailed (silver effect), has good delineation of space and instruments (silver effect), is fast (silver effect), and has agile bass (silver effect). But it doesn't have the emphazised treble and harsh upper midrange of the typical pure silver cable. So I think it has also to do with the shape of the conductors (ribbon, round or rectangular), the dielectric material and whether the conductors are cryoed or not.
Don't you notice that it is always the engineering types who feel a need to justify by first principles the sound of his system to others when all he has to do is start the music? or do they think that all that talk before hand is going to make it sound any better? reminds me of the religious types who need to convince others to shore up their weak faith ... Build your products with your theories, the heart and ears will be the ultimate judge. Theory and execution are two different things, only results matter.
Oh, forgot to mention, next time l went over to his house, he was using oval 9'S . Now he is using Nordost Heimdalls & VD power 3. Now, he is lusting after my Siltech Sig & Khamas. YmMV
hearing is believing. either i hear a difference or i don't hear a difference. at this point it's an anecdotal report which cannot be verified.
suppose i was listening blind and could hear the difference 90 percent of the time, what would an engineer say at that point ?
it seems that some people deny perception. granted there are psychological and physiological facors which affect perception. however, one can not deny it's validity if the evidence is meaningful.
Two weeks of theory is not going to convince someone who just heard a difference in the first 5 seconds of swapping. Justify all you want. Only hearing the music matters to me. Does not really matter if it is a placebo effect or what. I hear a difference is all that matters.
below is a message bet I sent several yrs back I just had an argument with a techno type about cables. Done it many times, its interesting. He said that cables do not make a difference. (Of course he is the engineer type who prefers the low cost solution backed up by theoritical claims that never faces the acoustic reality of the products that he supports)
So I brought him over to my house and switched out thin monster type cords vs a cheap pair of ps audio speaker cables(I don't even want to show him my real ones). Guess what, he heard a undeniable difference, which he then justifies by saying that the gauge size is different and therefore the resistance is lower and that makes a difference. So I asked him that if the guages were the same, then they would sound the same? He said YES! I then asked him if one were silver and the other were copper, would it make a difference? He said since the conductivity is different, the answer is YES! So I said if the gauges were the same and the same conductors were used, there would be no difference? He said YES! I asked again if the above two were the same but if 1 was a twisted pair(or coax) to better reject interference and the other was not, would there be a difference? He answered, anyone would know that a twister pair has better noise rejection so, the answer is YES! So I said that if the conductors were the same, the gauges AND the same geometries were the same, then they would sound the same? At this point, he suspects a dead a end trap and he pulses a long time before answering... Yes .... So I carried on, I asked if shielding makes a difference? He's cautious now, and answers, if in a noisy environment (like near power transformers ...), yes ... So I said "in order for cables to sound the same, then
all of the above must be the same? in which case you must have the same cable! RIGHT?" he went .... While he was quiet, I gave hime a couple more things to think about, like dieelectric, vibrations, skin effects, termination, static, etc ... He came back and said well, maybe they are not audiable ... at which I replied "you must be deaf or in denial"
Without personally witnessing your comparison technique, no one really knows what you're hearing.
Look, there is only a tiny percentage of Agon readers with adequate electronics background qualified to give explanations on electronics theory, based on decades of engineering facts. Instead of gambling on subjective reader opinions, call a spectrum of reputable manufacturers that aren't MARKETING cords with their gear.
It's amazing how so many put all kinds of faith into aftermarket companies peddling endless claims (not limited to audio), but the actual component ENGINEER'S aren't given enough credit for their designs and requirements. It's in their best interest if it made a difference, right? Speaker cabling and IC's are another issue all together.
The power cord type, supplied with a $6k amplifier (example), was sellected based on the component's power requirements, and is what was utilized to obtain the amp's engineered specifications, THUS obtaining the audible results that so-called "Audiophile reviewer's" base their "positive" articles on. (An entire story of it's own)
The more you know about electronics/powersupplies, you'll begin to understand why alternate cord conductors will have no affect on the component's output FREQUENCY response. I'm always open for further education, but please base it on engineering facts, or post some reputable articles for all of us to read, and preferably un-biased.
It is well understood how/why humans can convince their senses into believing all kinds things, and is why placebo and advertizing (all industries) work so well.
You have an open mind, experiment and listen for changes in your system. That puts you way ahead of the naysayers at this site who believe NOTHING of this sort can be detected by the human ear :^).
i was listening to my stereo system using an all copper line cord, gold furutech connectors, no solder connections, some dampening material in the cord feeding a tube amp.
i listened for a few minutes and changed the power cord. the second cord, had the same connectors, method of connection, dampening material, with copper and gold metals.
i heard a difference--a shift in the frequency response.
one line cord seemed to provide more extension top to bottom, while with the other there was some attenuation at the frequency extremes.
What technical articals are you extracting your "voltage bandwidth" vs "current bandwidth" findings from, with regards to this topic and powersupply requirements?
Spatial King, I was describing the very basics of amplifer power supplies, paying particular attention to the rectifer output/resevoir cap.
I know that the power bandwidth of most amps easliy extends beyond 20 kHz. Perhaps I did not articulate my thoughts precise enough, but I was not suggesting that an ampllifer's bandwidth is the same as the transformer. I was purposely not getting into too much detail. The question that Mr Tennis asked was how can ac-line cords affect frequency response. My simple answer is: I think that if there are ferrites or other inductive material involved in the construction of the cord, the inductance of this particular ac-cord may impede sudden fluctuations in current.
At the crest of the rectifed pulse, ie the charging pulse, the secondary of the transformer is now dumping current to the cap and the output device. It has to be this way or Kirchhoff's current law is full of hot air, which is not the case. The point I was trying to make is that during this brief moment the required current must ultimately come from the ac-line. If the ac-line is heavily inductive the instantaneous current performance may suffer. I have never tested this theory on a real amp with different power cords. I have done circuit simulations in PSpice and i'm just throwing this out there as one way high frequencies or dynamics may be affected by PC's.
After writing that last night, it occured to me I should also elaborate a bit. When I said bandwidth, I was speaking in terms of the amplifier bandwidth, and I still state that line cords do not affect it. But since we are discussing line cords, let me relate the term "bandwidth" to line cords.
First of all, there is a voltage bandwidth and a current bandwidth but they are not the same. With respect to a line cord, the voltage bandwidth needs to be only a few Hertz wide, say 58 to 62 Hertz or so. Although the voltage bandwidth is much more than this, it doesn't have to be as long as the line cord can pass 60 Hz without loss.
The current bandwidth of the line cord, however, has to be much wider. In this case, a bandwidth from DC or a just a bit higher than DC to at least 600 Hz or so will do the job. The current BW can be higher than this without any problems.
I think I will start a new thread regarding line cord bandwidth as there is much to explain and it is really off topic from this one; probably next week sometime.
Regarding RF: I didn't mean to imply the line cord acted like an RF antenna when it was powered. What I was trying to say, however vague, is that it can act like an antenna and pick up RF energy. Although this energy should be eliminated in the transformer or perhaps some RF network in the PS input, there are cases where it can actually get into the amplifier itself and cause sonic problems. In this case, switching line cords may or may not make a difference. However, that being said, you still have lots of ROMAX in the walls which can pick up RF, too.
Dpac996: I believe you have bandwidth of the amplifier and bandwidth of the transformer, line cord, diodes, surge capacities, line droop, line drop, and dynamic compression all mixed up. Amplifiers simply don't work the way you describe. The power bandwidth of the transformer is typically no where near the amplifier bandwidth and sometimes it is not more than 47 toi 63 Hz. The line cord has wider BW to be sure, but keep in mind the only frequency on the line cord is 60 Hz, at least in the US.
Metro04: I do agree that materials do affect performance, but not like interconnects. Line cords only carry one frequency, 60 Hz here in the US. Interconnects can carry bandwidths from DC to 100 MHz with ease, if you use the right one.
Reb1208: Actually, if a line cord were to really seriously limit the power amp enough that it began to get warm and soft, it is more likely that dynamics will be compressed, rather than bandwidth. You might find that the low frequency peaks, not the high frequency peaks, is what got clipped. However, bandwidth below clipping, will be unaffected.
For RF to propogate it not only requires some type of conducting surface, but the physics of the medium (IE the physical environment that contains the RF) play an important role. Effective transmission lines do not power cords make. True certain frequencies of RF energy may attach to the surface of things other than metal, but in our case, audio amplifiers in metal cases, with power cords going in and cables I/O etc...which under normal conditions are shielded enough. I believe that very few home audio amplifers have ever fallen victim to any incident RF of enough energy as to be noticable.
This report of hard or glassy audible results from "RF" ...where does this come from? Have these types of claims been investigated? Have tests been run where an audio amp and cable have been exposed to swept RF sources while listening tests and/or controlled measurements of the device under test are performed? I highly doubt it.
Like the study of speaker cables, etc... it is a hard test to do and there is no shortage of opinions on the subject.
Remember, we are talking about engineered products. Yes we derive pleasure out of them but, there are cold hard facts based on decades of knowledge and years of experience put into the designs we love... We need to stay true to the basic facts of engineering and device physics to truly have meaningful conversations about it.
Back to the question: How can a line cord affect frequency response? In a typical audio amplifier power supply, on one side (we will call it the ac-line side) the transformer sees some resistance (from the dozens of feet of ac line going all the way back to the transformer on the pole), some inductance, and some capacitance. -Aside: homes typically have 12/14 gauge un shielded solid copper wire that is the standard. Increasing the diameter of the power cord to say 10 or even 6 gauge does nothing to the instantaneous current available "out of the wall". SUre current densities may be different on fat and skinny conductors, but the end result will be the same. These lines are in series.
So the transformer, itself made of two massive inductors wound around some magnetic core decouples the amp-side windings from the line-side windings. This is good news. ANy dc offset on the line side, besides having ZERO effect from the power cord, can now NOT "get across" to the amp-side winding.
SO, on the the next stage: the recitifers. So now we have a sinusoidal 50/60 hz signal driving a bridge rectifer of some sort. You have AC going in and rectified AC going out of the rectifer. THis means that, if you looked at the signal out of the rectifer's positive terminal you would see the negative going waves are now inverted and you only have positive ac-bumps, spaced either 50/60 hz apart or 100/120 hz apart, depending on the overall design of the rectifier stage. To "make" DC the rectifed pulses charge capacitors. With ZERO loading on the caps,(ie output transistors completely off) the charging currents from the rectifer gradually reduce as the caps reach full charge. The caps can only be charged at a rate directly related to the ac-line frequency. In the typical class A or A/B output stage design...one of the three pins of the output transistors (either FET or BIPOLAR) are connected to this supply "rail" thus allowing useful operation of the device (I left out the other pins to simplify the discussion).
So now, imagine that the output transistors have a job to do and are now driving a speaker load. The current source for the output transistors comes from: 1) The resevoir caps directly -- during moments the recharging pulses from the rectifier are absent 2) The rectifer/power transformer directly -- During moments that the signal to be amplified places its demands on the output device during charging times. Under this condition the power supply current is not evenly split among recharging the cap and output device. Here is where a good stiff power supply carries the day for audio amps.
In the context of number 2-- consider higher frequencies that require amplification... it is very possible that higher frequencies cause related current spikes through the rectifer stages and back to the transformer/power cord/wall etc... ...also consider 'dynamic' signals such as drums requiring current during this window...
If you have a power cord with extensive ferrite beads or other ferrous material, it is possible that under these conditions, the higher frequencies may be diminished, due to increased resistance to the current at these frequencies b/c of the inductive response from the ferrite. This is why, I think, that ferrites in power cables may diminish dynamics or dull the high end.
It is more from a reducing-the-available-current-under certain-conditions effect than an actual designed filter result, though one can mimic the other.
Of course, the transformer itself has a frequency response and this may over-ride anything else by orders of magnitude under the high frequency analysis.
Not sure if I completely agree with the power cord acting as an RF antenna. Once energized, it has more rejection qualities, and is more susceptible to large electro-magnetic field influences. Even placing two energized cords along side each other, will have little or no effect on the other's audio component. The newer switching class-D amps can inject adequate hi-freq noise into close-proximity sensitive interconnect cabling and component gain stages (even through some cable shielding and metal chassis), but would be hard pressed to have an audible affect when placed several yards up stream, along side another amp's un-shielded PC (via an extention cord for testing purposes). Oh, and can't forget about all the non-shielded Romex behind the sheetrock walls. Mainly what people hear from two-way radio communication, is affecting radio/television receivers or inadequately shielded sensitive components and IC cabling. That's the only time I've ever heard anything during audio playback, and I live next to a private air park where communication takes place throughout the day. I'm open to explanation, though.
Reb1208,
Regarding conductor materials... copper, silver, or gold are capable of frequencies into the extreme RF bandwidth. The audio bandwidth is child's-play in comparison. Copper is utilized everywhere in these applications. Capacitance, impedance, and shielding are the main issues affecting an interconnect's frequency/performance, as they do with RF cabling or wave-guides.
Not real sure how or why you're having issues with shielded cords creating coloration. Any further explanation to help us understand what might be contributing to your findings?
I have followed this thread closely and until now have not felt like saying anything. But the last post by Sp has sparked me to reply.
Over the past ten years or so I have listened to atleast 100 or more power cords in my system. Never satisfied with the results, I started building my own. At last count, probably 30 samples. Every type of wire, geometry , shielding method and terminations imagineable.
None of my final designs, with the execption of (1) are shielded. Shielding, IMO adds an audible coloration that I find quite annoying.
The question, "how can a line cord affect frequency response?"
Based on my experience, the #1 factor by far is the type of conductor material the cord is built of. Everything else is secondary. How?, the same way an interconnect does. Use conductors that restrict bandwidth and the frequency response will be adversely affected.
The power cord doesn't affect frequency response, however it can affect dynamics and in some cases become an antenna for RF. When RF gets into your amplifier, then it can affect the sound in many ways:bright, lean, hard, glassy, etc. Normally, the power supply should eliminate these effects, but in some cases, it doesn't.
It never ceases to amaze me just how cheap some expensive amplifiers can be. Some factory power cords are really inexpensive. When you replace them with better quality ones, there can be a small difference in DC levels in the power supply, which you will hear. However, none of this will affect frequency response.
Whether or not you will get the same effect(s) with a Belden 14 gauge shielded power cord for 10 or 12 bucks is a whole different matter.
Boa2, my PCs quack real loud all the time. Especially when I take a wild gander, and goose 'em real big 20 amp IEC male connector down those ornithologically inappropriate tini 15 Amp female receptacles. Perhaps Robert should offer a new line of PCs insulated with authentic Canadian Artic Goose Down. . . or should we leave it to Virtual Dynamics?
As for Albert influencing the rest of us to buy his gear, of yes, every time he upgrades, a number of us tail waggers sit there drooling and waiting for the hand-me-down table scraps. 8-) And Albert, did you notice the Wotans for sale? Or are you holding out on a pair of JL-2s or quad of JL-3's?
I'm almost at the point, after 28 years in this hobby, that I believe there is no bad product, it's all synergestically related.
Thank you for your post. I agree completely, John. Your comments are thoughtful, and they remind us of how often in these discussions the focus is on winning rather than enjoyment.
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