The first mile: What power stations are best for audio?

[mansr]

Of course it isn't perfect, and neither is the design of an amplifier. Yet you say a properly designed amplifier won't act differently with a cable that is quick to respond to transient demands than it will to one that is slower to respond. And I say the power grid is properly designed, such that a model of an amplifier's transient power demands may assume the supply to the box outside the home does not in practicality limit those demands.

 

I'm saying a properly designed power supply is sufficiently immune to minute differences in transient response on the primary side that the impact on the signal output of the amplifier is negligible. If this is not the case, why is nobody able to show measurements demonstrating it?

[sandyk]

If this is not the case, why is nobody able to show measurements demonstrating it?

 

For the same reason that you and your E.E. buddies are unable to show measurements at the analogue output of a DAC where different USB cables , Regens etc. are used ? Or could it simply be that they are so damn confident of their own ingrained beliefs that these things are not possible, that they would never bother even trying to find out the truth because it involves a lot more time and effort than they are willing to put into it ?

Talk is cheap !

[sdolezalek]

I can't help but wonder whether this conversation is the equivalent to one we could all have had about noise through USB cords before a significant number of us experienced the litle Uptone Regen in our systems and came to a different conclusion -- one that has now created an entirely new product category of the high-end USB hub (with the iFi iUSB3.0 recently joining the party).

 

What we know is that devices like the Regen have a greater or lesser impact based in part on just how well the USB signal is handled at both the computer and DAC end of the chain and that some systems benefit little, if at all, and others quite a bit. Add to that the impact that the length and nature of the connector between the Regen and the DAC seems to be quite important (the "last six feet equivalent of the power cord" or in this case the "last inch")

 

Why would it then be so surprising that the construction of six feet of power cord might have similar differential impacts in differing systems? Might the level and quality of shielding make more of a difference in some homes than others? Might the cable construction and things like skin effects and slew rate have more of an effect on some amplifier and capacitors than others?

 

As with the Regen, you might say: "not needed if the other components are built correctly," but how sure are we that the components we have were built to that standard? Isn't that why we try new stuff in our systems from time to time? I'd have to guess that the true answer might be: "It can make a difference, but the cost of constructing a cable to make that amount of difference would far exceed the cost of a better design on the amp end (or maybe a better power supply on the other end). That would be a fair response.

[One and a half]

I'm saying a properly designed power supply is sufficiently immune to minute differences in transient response on the primary side that the impact on the signal output of the amplifier is negligible. If this is not the case, why is nobody able to show measurements demonstrating it?

 

You'd be surprised how much low frequency hash from say the 5th Harmonic and higher (of 50 or 60Hz) ends up in the system especially at the other end (at the speaker) and yes totally dependent on the design of the amplifier.

 

This article posted by Prof. Raif Smith at Polk Audio [studies on Residential Power Line Noise Parts 1-9](quite lengthy but very good read) shows the effects of lower order harmonics on the AC supply on the speaker terminals. Different AC cables, Ac sources were used, and correspondingly FFTs are shown, the actual values would have been nice for some, but you can't have everything I suppose.

 

When I repeated the same measurements at home, at the speaker end feeding a 1kHz sine wave at the amp input from a computer signal source, the FFT showed only 1kHz spike, there were no other values at all. This tells me the amplifier I measured does filter out the garbage from its own rectifier network and the AC supply harmonic residuals which are pretty low to begin with using a balanced AC supply, or my scope wasn't good enough to read, but zero is zero!

 

So rather than concentrate on what's miles away at the power station, the greatest source of noise is in the home as Jud has advised, since close proximity has little attenuation and more trouble. Dedicated spur lines from the distribution board help since this puts a distance between appliances in the house and audio components, distance = attenuation ++ , that's what we want, but also have to deal with the locally emitted gunk, especially from power amps at high volumes. That is not so easy and no magic bullet either, as often the harmonics creature is like a Hydra, cut one end off and end up with two more in a different place.

[Jud]

I'm saying a properly designed power supply is sufficiently immune to minute differences in transient response on the primary side that the impact on the signal output of the amplifier is negligible. If this is not the case, why is nobody able to show measurements demonstrating it?

 

But once again: Saying someone else has not done measurements showing the opposite (at least that you are aware of, since it appears from what One and a half has said there may be some material from audio companies, and I have not heard you say you've done a search in the academic engineering literature) and speculating on the reason is not the same as saying "I have measurements to demonstrate this."

[Jud]

Why would it then be so surprising that the construction of six feet of power cord might have similar differential impacts in differing systems? Might the level and quality of shielding make more of a difference in some homes than others? Might the cable construction and things like skin effects and slew rate have more of an effect on some amplifier and capacitors than others?

 

Don't know one way or the other, as I haven't seen anything conclusively demonstrating either that it makes a difference or that physics says it can't.

 

As with the Regen, you might say: "not needed if the other components are built correctly," but how sure are we that the components we have were built to that standard? Isn't that why we try new stuff in our systems from time to time? I'd have to guess that the true answer might be: "It can make a difference, but the cost of constructing a cable to make that amount of difference would far exceed the cost of a better design on the amp end (or maybe a better power supply on the other end). That would be a fair response.

 

Or "It can make a difference, but engineering design principles dictate it would be better placed outside the component," as with Berkeley's decision at least ostensibly on engineering grounds (best isolation is one I recall) to make its USB -> SPDIF converter a separate piece from its DAC.

[eternaloptimist]

For the same reason that you and your E.E. buddies are unable to show measurements at the analogue output of a DAC where different USB cables , Regens etc. are used ? Or could it simply be that they are so damn confident of their own ingrained beliefs that these things are not possible, that they would never bother even trying to find out the truth because it involves a lot more time and effort than they are willing to put into it ?

Talk is cheap !

 

Yes... talk is indeed cheap. So are claims about apparent differences heard with different USB cables etc.

 

How many times does the phrases " Extraordinary claims require extraordinary evidence" need to be voiced?

The onus is not on the Electrical engineers to show an audible difference when there is no measurement difference. The onus is on the subjectivists. While the pretty packaging and the "aircraft grade" aluminium is visible etc., the psychology will be strong...

You have been around the forums here long enough to hear about psycho-acoustics (which are well established) so I will save more keystrokes.

 

Also please note, I am a self-confessed hypocrite I have a linear PS to my Audiophilleo (can I hear a difference? not at all sure, not convinced!) and a nicely made Supra USB cable (!! No difference, but is a nicely made cable!). Would I claim any differences heard un-blinded in much of my gear are not psycho-acousitc? Not at all. Will I hear the difference in a blinded test with cables etc. Almost certainly not! Speakers definitely. Pre-amp definitely. Power amps... not sure.

I don't then say the EEs are wrong....

[mansr]

For the same reason that you and your E.E. buddies are unable to show measurements at the analogue output of a DAC where different USB cables , Regens etc. are used ?

 

You mean the obvious reason that there are none?

[mansr]

You'd be surprised how much low frequency hash from say the 5th Harmonic and higher (of 50 or 60Hz) ends up in the system especially at the other end (at the speaker) and yes totally dependent on the design of the amplifier.

 

Again, that's not what I'm talking about here. The only measurement presented by Shunyata for their power cables is the transient response to switching a high-current load (several hundred amps), so that's what I'm talking about, and it has nothing to do with with harmonics or noise induced by other appliances. In order for the Shunyata graphs to be relevant, you'd have to plug the power cord directly into a perfect, zero-impedance power source, something the mains supply at your house is not. The substation transformer is probably close enough that we can ignore the high-voltage power lines beyond it, but the mile or so of wiring between it and your house contributes the majority of the impedance between the power source and your amp no matter what cable you use for the last few feet. Why is this so hard for some of you to grasp?

[sandyk]

Yes... talk is indeed cheap. So are claims about apparent differences heard with different USB cables etc.

Bury your head in the sand, and ignore the vast volume of these subjective reports at your own peril. All you need to do is look at the output end of USB cables with a C.R.O , or the +5V wire at the device end, and you will see the effects of SMPS noise etc, that is coupled into the D+ and D- leads, or even low level packets of Data on the +5V wire can be seen when data exchange is taking place. Differential receivers aren't perfect .

 

You have been around the forums here long enough to hear about psycho-acoustics (which are well established) so I will save more keystrokes.

Sure have. That's why I passed some of my findings on to E.E. Martin Colloms and others for confirmation.

 

Will I hear the difference in a blinded test with cables etc. Almost certainly not! Speakers definitely. Pre-amp definitely. Power amps... not sure.

Surely you jest ? There can be vast differences between Preamps and Power amps. At the Sydney listening sessions that I attend fairly frequently, most of the time, more than half those present don't even know which device is actually in use until afterwards. Much of the time, the inactive devices are left powered up to sound at their best when compared, so you can't go by indicator LEDs or displays either .You only need suitable source material from something like "The Storm" from a Chesky Hybrid SACD and good speakers, to hear how one sounds like a storm, but the other makes you involuntarily jump a bit.

One amplifier may even give a realistic impression of height, whereas the other doesn't. e.g. Gryphon Mono blocks vs. Nelson Pass 150W Class A monoblocks. The Pass was WAY more realistic sounding.

[mansr]

Bury your head in the sand, and ignore the vast volume of these subjective reports at your own peril. All you need to do is look at the output end of USB cables with a C.R.O , or the +5V wire at the device end, and you will see the effects of SMPS noise etc, that is coupled into the D+ and D- leads, or even low level packets of Data on the +5V wire can be seen when data exchange is taking place. Differential receivers aren't perfect.

 

Nobody is denying that there are measurable differences at the output of the REGEN. What's lacking is evidence that these difference are in any way measurable at the DAC output.

[Jud]

How many times does the phrases " Extraordinary claims require extraordinary evidence" need to be voiced?

 

That's a very interesting notion. It's one I agree with, but here's the kicker - we are then required to decide just what is an extraordinary claim.

 

Many laypeople in the United States (nearly half of everyone surveyed) believe the Genesis version of origin of species rather than the theory of evolution. Does this make the theory of evolution, more than 150 years after publication of The Origin of Species, a set of extraordinary claims? Should we require extraordinary evidence, for example p-values of .01 rather than .05, for all published statistics supporting academic papers on evolution? What about quantum physics, which is just as damned weird and unbelievable as anything can be? Should we doubt quantum entanglement or the existence of the Higgs boson because all the experimental data in support hasn't been held to a higher than usual scientific standard of evidence?

 

The onus is not on the Electrical engineers to show an audible difference when there is no measurement difference.

 

People, including electrical engineers, are starting to show measurement differences. And electrical engineers are among the people saying the differences are audible. So who's the onus on now?

 

Frankly, I don't think that last question is a particularly interesting one. It's more a lawyer's question than a scientist's. What I'm interested in is what's coming next. Will we see some measurements that demonstrate differences of a type and quantity that should be audible, or not? The anticipation is exciting.

[mansr]

That's a very interesting notion. It's one I agree with, but here's the kicker - we are then required to decide just what is an extraordinary claim.

 

Many laypeople in the United States (nearly half of everyone surveyed) believe the Genesis version of origin of species rather than the theory of evolution. Does this make the theory of evolution, more than 150 years after publication of The Origin of Species, a set of extraordinary claims? Should we require extraordinary evidence, for example p-values of .01 rather than .05, for all published statistics supporting academic papers on evolution? What about quantum physics, which is just as damned weird and unbelievable as anything can be? Should we doubt quantum entanglement or the existence of the Higgs boson because all the experimental data in support hasn't been held to a higher than usual scientific standard of evidence?

 

There are mountains of evidence in support of both evolution and quantum mechanics. The audiophile equivalent proof for the Higgs boson would be some guy at CERN saying he felt a tingling in his left arm that he's certain was caused by the presence of Higgs bosons while the experiment was running.

[sandyk]

You mean the obvious reason that there are none?

 

Dream on ! Everybody else in the forum who reports hearing these differences must be delusional, and you and a few of your E.E. mates are the only ones with a grip on reality?

Incidentally, I have never claimed to hear differences between various types of USB leads, but I have heard , along with all the others present at a recent Sydney listening session, the vast difference a USB Regen powered by a much better PSU than the supplied wallwart made, when used between a Windows laptop and a Bricasti M1 DAC.

From an email received the next day.

WOW! What a positive difference your diy power supply made when plugged in to the Regen. I stopped analysing the sound and was enveloped in the music....

[Jud]

There are mountains of evidence in support of both evolution and quantum mechanics.

 

Gee whiz, really? Way to miss the point. Scientists did not treat the lack of, e.g., certain fossils prior to their discovery, or cross-confirming evidence before genetic testing was available, as disproof. They waited and adjusted their assessments of what was scientifically "known" as the evidence accumulated.

 

Once again: Lack of confirming experiments thus far (at least to our own knowledge - I haven't made a thorough literature search, and you haven't said anything about having performed one either) is neither proof nor disproof. I am very comfortable saying "I don't know" rather than "We don't have confirming evidence at this point so it should be considered wrong." (This is a favorite trope of non-expert laypeople on evolution blogs - "You don't have the evidence, therefore we win," a/k/a the "God of the gaps" argument.)

[sandyk]

What's lacking is evidence that these difference are in any way measurable at the DAC output.

 

That's primarily because those who dispute this, and are suitably qualified, are too lazy to get up off their arses and try and measure them! Instead, they usually demand that those who make such claims should provide the proof, while knowing full well that they don't have the training, expertise or test equipment to do so.

[mansr]

Gee whiz, really? Way to miss the point. Scientists did not treat the lack of, e.g., certain fossils prior to their discovery, or cross-confirming evidence before genetic testing was available, as disproof. They waited and adjusted their assessments of what was scientifically "known" as the evidence accumulated.

 

Once again: Lack of confirming experiments thus far (at least to our own knowledge - I haven't made a thorough literature search, and you haven't said anything about having performed one either) is neither proof nor disproof. I am very comfortable saying "I don't know" rather than "We don't have confirming evidence at this point so it should be considered wrong." (This is a favorite trope of non-expert laypeople on evolution blogs - "You don't have the evidence, therefore we win," a/k/a the "God of the gaps" argument.)

 

Quantum mechanics started as a theory formulated to explain observations that science at the time didn't account for. This theory was then used to make predictions and experiments were devised to test them. Once in a while, an experiment has an outcome different than the expected. When this happens, the first thing scientists do is try to replicate the results, preferably in a different facility. If the unexpected results are found to be repeatable, the theories are adjusted accordingly, new experiments are devised to verify the changes, and the cycle repeats. Correct predictions strengthen the theory, and false ones weaken it. I don't see this process being applied at all when audio tweaks are discussed.

[Jud]

Quantum mechanics started as a theory formulated to explain observations that science at the time didn't account for. This theory was then used to make predictions and experiments were devised to test them. Once in a while, an experiment has an outcome different than the expected. When this happens, the first thing scientists do is try to replicate the results, preferably in a different facility. If the unexpected results are found to be repeatable, the theories are adjusted accordingly, new experiments are devised to verify the changes, and the cycle repeats. Correct predictions strengthen the theory, and false ones weaken it. I don't see this process being applied at all when audio tweaks are discussed.

 

No, nor when they're disputed, which has been my point through this discussion. As Alex (sandyk) mentioned, there's a dearth of experimental testing with adequate equipment on *both* the pro and anti- sides of nearly any heated audio discussion you want to name.

 

John Swenson has laid out pretty specifically the testing program in which he intends to engage (or for all I know is presently engaged) in order to measure changes at various points in the DAC's digital circuitry, and the limitation that prevents him from "going the last mile" and measuring differences at the analog output of the DAC. (The limitation is that to do reliable measurements, one needs measurement equipment that exceeds the capabilities of the thing being measured by an order of magnitude or more. To reliably measure differences at the DAC's analog outputs and relate them reliably to the digital inputs, as I understand it this means in essence one would have to construct by far the world's best DAC.)

 

Assuming for the sake of discussion John successfully carries out the measurement program and shows results that support his hypothesis, then one can choose to say "OK, so far so good, though we don't have the conclusive analog measurements;" or "A-ha, yet *another* instance in which the hypothesis is not established!" I tend more toward the former. I get the feeling you tend more toward the latter. I do not think the latter is more "scientific."

[Boris75]

The audiophile equivalent proof for the Higgs boson would be some guy at CERN saying he felt a tingling in his left arm that he's certain was caused by the presence of Higgs bosons while the experiment was running.

 

This is a wonderful metaphor

[Jud]

This is a wonderful metaphor

 

I think its wonderfulness depends quite strongly on how idiotic you feel audiophiles are.

[crenca]

I think its wonderfulness depends quite strongly on how idiotic you feel audiophiles are.

 

I know am new to this world and thus run the risk of "first impression" bias, but I am frankly frightened by the number of "audiophiles" that argue for a completely "subjective" "emotional" perception, of say what a $1000 power cord does (I won't use the word "idiotic" here ).

 

Worse, I am frighted by how many in the audiophile press explicitly argue that a radical subjectivism is all there is to it...

[Jud]

I know am new to this world and thus run the risk of "first impression" bias, but I am frankly frightened by the number of "audiophiles" that argue for a completely "subjective" "emotional" perception, of say what a $1000 power cord does (I won't use the word "idiotic" here ).

 

Worse, I am frighted by how many in the audiophile press explicitly argue that a radical subjectivism is all there is to it...

 

Why frightened, and why "radical subjectivism"? I don't see people using words like that about people willing to pay huge sums for bottles of wine or bourbon, or violins. (The first and certainly the last of these dwarf sums paid for audio equipment.) Yet in those fields too there have been blind tests in which connoisseurs are unable to reliably tell the high dollar stuff from the rest.

 

I personally very much like the idea of exploring the possibility of getting better (in my personal definition, closer to real or "live") sound through good engineering and science. But I have no worries about how anyone else may want to approach audio for their own greatest enjoyment. I have a great time chatting with people here who come at the subject from all sides, from "radically objective" (without double blind ABX tests, we can't credit reports that jitter affects the sound below at least twenty nanoseconds, that DACs or amps or filters or player software or computers/servers or different resolutions of music or certainly cables sound different from each other) to "radically subjective" (we should trust our ears only). I have the great advantage of knowing so little that nearly all the folks here have something interesting to teach me.

[crenca]

Good points Jud. I suppose I would say that while the taste of a wine or food is subjective, what is a "real live" sound has an objective element in reproduction (fidelity). There is a whole "sales job" being done around what is more fidelis. On the other hand, the subjectivists are claiming fidelity does not actually exist (which leads to an absurdity), so in those senses it is not like a preference for this or that flavor of food.

[Paul R]

There are mountains of evidence in support of both evolution and quantum mechanics. The audiophile equivalent proof for the Higgs boson would be some guy at CERN saying he felt a tingling in his left arm that he's certain was caused by the presence of Higgs bosons while the experiment was running.

 

Oh phooey - that's just nonsense.

 

There are two significant differences - measurements are not done in the environment where most people do the greater part of the listening. This may or may not be a significant factor, but most people I know would condor it possibly significant. Or in other words, it is impossibly difficult to eliminate the environment as a factor.

 

Second, the last and most telling test instrument is a person listening. This has so many variables that it is non-sensical to even try and draw any universal conclusions from - well - from just about *any* number of tests.

 

Lastly, something is convincing many many people that they hear a difference. It is not only wrong to claim that is nothing more than expectation bias - it is plainly a stupid thing to do.

 

Just as stupid however, is to ignore the fact that expectation bias and other forms of bias play a part of the judgements of what we hear. Blind, sighted, or otherwise delivered, test results from individual listening tests are unusable and probably invalid because of this.

 

So, you tell me - what is the better choice - tell people they are imagining what they really do hear, or tell people that current technology is incapable of measuring differences that people here? Or some other "easy answer" in between?

 

For my money, I bet until we get telepathic and can actually see inside another person's mind, we might never know all the answers to this.

 

-Paul

[Jud]

Good points Jud. I suppose I would say that while the taste of a wine or food is subjective, what is a "real live" sound has an objective element in reproduction (fidelity). There is a whole "sales job" being done around what is more fidelis. On the other hand, the subjectivists are claiming fidelity does not actually exist (which leads to an absurdity), so in those senses it is not like a preference for this or that flavor of food.

 

You know there are chemical measurements for the constituents of food and wine, right? And what about the sound of a violin? I'm not going to let you say the comparison isn't an apt one that easily.