This is a minor correction to my last post in this thread.
Jitter is measured in picoseconds, not nanoseconds. That's how sensitive clock circuits are. Jitter in the order of 300+ picoseconds already has a major impact on sound quality from a digital source. You'll hear that as a "fuzzy" imprecise soundtage.
One picosecond is one milionth of one milionth of a second, or ten to the minus twelve for you techies...
You don't need much to cause harm! |
Snofun3: I tried zipcord and didn't like it, so what should I do? Listen to it anyway?! Please solve my dillema for me!
My solution is to listen long term. In the end, you get a good feel of the character of sound. Obviously that is not something you can judge in minutes.
Do the same "test" on fine wines, any gourmet food, fragrance, whatever. Short tests like that consistently fail to reveal any statistical conclusion.
So, what does it mean?
Either that we should all just buy the cheapest XYZ everything or that the test is faulty. I say the test is faulty and you say it ain't. Please offer a scientific way to resolve this shouting match... Good Luck... |
If you trust DBT, then let me suggest a simple test to make anyone laugh. Borrow a $99 boombox with a CD player and play it through your main speakers instead of the little plastic pieces that come with it.
Play it and your main system with the levels equalized and make sure the little thing is not clipping, please... I bet you won't be able to identify which is which in a controlled DBT!
Does that mean you should sell your main rig and replace it with a cheap boombox?! Heck no!
You know better and so does Mr. Russel, who still urges you to buy his high-$$$ Mac gear (nothing special to my ears).
Go ahead -try this "test"... You're guaranteed to have fun, that's the only thing I can say...
Do you want a scientific reason for the failure of DBT? There is a mountain high of research paper on the short term memory of humans. Our sound memory is pathetically short, like 5-10 seconds. We are limited physiologically, but let's hope our brain can identify our mental weaknesses and compensate for them. Otherwise, music may only mean tones or sound pressure. Those will make sense as battle bugles, but where is the emotional content?
How does Mr. Russel explain that?
It's easy to show what research has shown again and again but then he does not bother to explain the rest of the dillema. If that was the end of the story, we would be maybe talking, but singing? Playing music? What's that good for?
Listen long term. That is the only way to assess your emotional satisfaction. We can't have extreme pleasure turned on and off under test conditions. Our brain is too dumb for that...
But it does know averaging... It does remember when the music comes out more realistic and more engaging. If you don't trust your own ears and brain, might as well read the music off the printed paper. It's the same content, isn't it? Oh, I love that C-sharp!!! |
The following is my engineering interpretation of power cord contribution to good sound. If you have to ask, then I also didn't think they'll make a difference, but reality strikes, my friend!
I've heard amps distorting big time with certain (expensive!) power cord while other amps sounded great with the same. Nothing wrong with either amp!
So why is it?
If you interpret power cords as extension of the "miles and miles" of Romex, inevitably it sounds real dumb that they'll make any difference.
Here is what they are: they are the piece of wire that is closest to your equipment. BIG DIFFERENCE.
Why?
Because audio equipment is affected by NOISE. It's supposed to amplify 20 Hz to 20 KHz, but the circuit doesn't know that!
Audio circuits pick up radio frequency and "mix" it with the audio. This is no technical mumbo-jumbo. Just ask any RF engineer about intermodulation with circuit non-linearity and they'll pull a stack of papers on the topic. Very scientific.
The "funny" thing about radio frequency is that it radiates from antennas and picked up by antennas. The antenna has to be related to the wavelength of the RF emmisions, so short wires are almost "perfect" for that. Yucks!
Well, you might say, there is no short wire. It's an extension of miles and miles. Not so!
When it comes to very high frequencies, the wire's miniscule inductance (very scientific - check technical specs!) is large enough to make the far end of it irrelevant. That's a great simplification, of course, unless one wants to solve Heavyside/Maxwell equations. I don't recommend that...
Now that we understand the nature of wires in close proximity, perhaps we'll be more open-minded about the effects of these wires on the system.
Now, those of you in the rural area might think that they don't have RF pollution to worry about... Wrong!
Guess what. The power supply in any equipment is a source of RF noise. Ahh?! Say what?!
If you have a high speed scope, pull it out and sample (at your own risk!!!!!!!!!!!!!!!!) the rectifier diodes at the switching point. Zoom in and enjoy the view!
There are several mechanisms in which RF pickup muddies audio. One was mentioned above - direct mixing. The most common might be the impact on jitter in digital audio sources. RF has its nasty ways of leaking through stray capacitance. In average equipment it takes very little effort to reach clock circuits and add a few nanoseconds of "fuzziness" to your timing reference. This topic has been analyzed to great boredom, so just search for exact details. The jist of it is that very few nanoseconds of jitter are enough to cause distortion of the non-harmonic type - the worst there is. Audible products that do not relate to the music tones!
If you don't accept that jitter is an issue then you are seriously wasting your time reading all the way to this point. It's too scientific, perhaps.
So now we understand three things:
1) short wires in close proximity to the equipment differ from miles of Romex in regard to RF rejection (elementary Physics).
2) Any system with a power supply emmits RF. (you can verify this yourself - again: at your own risk!!!!!)
3) Low levels of RF mixed with audio are not nice. (Just ask any RF engineer)
Any more comments about the "myth" of power cords?!
Mind you, I don't advocate paying $2,000 for these, but at least be aware that they are doing something other than draining your bank account. Some power cords do RF filtering extremely well! |
Bigjoe: I agree that it's best to correct the problem at the source, but most people just buy equipment to listen, not to fix it...
Coming from some background in power electronics (many years ago...), I appreciate these issues. Unfortunately I find that quite often audio engineers concentrate on the audio part of their gear and the power supply is sort of an afterthought. Real sad!
But it's "only" a power supply... Dah!!! |
Snofun3: My claim is very simple. Since the method proposed (i.e. DBT) is worthless (and there is lots of scientific data that says that is true) for determining audible differences (whether they exist or not) then my proposal is to make a judgement based on long-term listening. The goal is to enjoy the music, so test equipment is marginally relevant (how do you test joy?!)
So, at least I have a proposal, rather than say it's all BS, even though many of us believe they have more joy with certain components.
You can say that you don't agree, and instruments are the only thing that counts, despite their faults. Then you'll say NO and I'll say YES and we'll go on (theoretically) forever. In that case it becomes a "religious" discussion rather than a logical one.
The other option is for you to have an alternative proposal, so we can discuss it.
Or just buy a boombox. They're fine for making noise in the street, but I still say that you (and I) won't tell the difference between that boombox and a Krell with Wilson speakers - not in a DBT... |
Snofun3: suddenly the difference was, errr, let's say, much less perceptible So, are you saying that you are **as satisfied** with your system in the **long term** with Radio Shack cables or generic 99 cent interconnects from the flea market? If so, then I understand you although I don't agree. If not, then there must be something "else" that the **test didn't catch**. That's all I'm saying. |
Mark02131: There is not a shred of "scientific" evidence that says any such thing Not the DBT itself, but in regard to our sonic memory. But why hypothesize about it? Try it yourself as I proposed with a boombox and your $$$$ system. I've been a participant in one well-conducted DBT and I've talked with the person which ran the test. He has quite a bit of experience and scientific background in audible perceptions and I believe his word is quite credible when he tells me that there is enough scientific data on the subject to show that statisticaly most participants are just guessing. I'm interested in any other data do you have that supports other conclusions. |
Then you'll understand why people really can hear differences between boomboxes and better systems Same speakers (for frequency response) and level matched? Is that a real claim - or a guess? I'm smiling here... cause I know the answer... |
Pabelson: Of course boomboxes have their own speakers - crappy ones with tonal anomalies and bass rolloff. You must equalize the spectral coverage and levels to have any meaningful conclusions. Furthermore, if you take what you would consider a bad sounding (but not clipping!!!) boombox even through the good speakers, one that you are willing to bet your life on finding in a DBT, let me give you a friendly advice: Don't bet your life!
You will not identify it in a statistically meaningful way! |
If you eliminate all the factors that make things sound different, then they sound the same But they don't sound the same and even YOU will notice that. Yet, you will not identify the boombox in a DBT. I'll bet $1000 against your $100, how about that. It's a farse, coined around the $15,000 "challenge". Both are a farse. Geddit? Bad test. Nothing else I have to say... |
Pabelson: you have to invent and carry out some sort of blind test You got it... A long term test... How do you know you're not imagining a difference You can measure differences (how about 0.25% difference?) in THD between the two and still won't be able to tell the difference in a conventional DBT with one minute clips. What do you think?! The answer is, you don't know, and you can't know unless you compare them blind So, when (not if!) you fail the above test you will sell your main gear and listen to a boombox for the rest of your life, just because you arbitrarily decided that "you can't know unless you compare them blind"? The emphasis is on arbitrary, until I see a conclusive research that shows consistent statistical correlation of DBT to sonic perception. Without that, you are making an arbitrary decision that the particular method is a good indicator. I'm looking for the science here. Go back and look at the roots of scientific evaluation. Even Einstein's theory of relativity had to wait many years for "official" proof, until someone could measure the effects of gravity on light. We tend to simplify and take things for granted, but that is not scientific. What's scientific is for one to ask why isn't reality in agreement with Newtonian mechanics and dare say that the speed of light is constant, risking ridicule by his colleagues. You can ignore what your brain tells you based on what seems to be an incomplete or insufficient test data. That is not science, even though it includes scientific methods. I'm sorry that I don't know the answer, but I do know what to ask. You don't! You seem to accept it that someone with X years in the audio industry "gotta know" more than what your own ears tell you. With that approach we wouldn't have an atom (which nobody could see at the turn of the twentieth century!) and would be still teaching Greek geometry instead of Calculus in our schools (Newton was "blamed" to be insane with his definition of infinitesimals...) Dare to question! |
Someone should make a little $100 box that implements a tunable band-pass filter to put in the interconnect lines. I bet that you could make such a box with some knobs that would let you make your interconnect sound like "silver" or "copper" or "quantum equalized equipotential polarized dialectric" cables. Zip cord plus a box like this would be as good as any $15000 cable. That's the Carver "theory" applied to cables... And it is not true. A "box" with passive or active components does not behave the same as a transmission line in regard to RF handling or even in regard to the full audio spectrum. You are making a big simplification of what should be analyzed by Maxwell equations and perhaps simplified to distributed network. The "box" theory says that it all can be simplified into an "ideal" transmission line plus ideal basic components. That's known in engineering as the first-order approximation. It's good for predicting basic directions, not for details. BTW, you can simplify the concept even further by putting an equalizer in the chain. If all these transfer functions are linear then you can "bundle" them together! Some online magazine measured and published Nordost Valhalla capacitance curve. No passive components that I can think about can do that... Equalizers do some good in some systems but they are not "sonically-free", whether active or passive. If you bother to reach the highest levels of audio reproduction then you will take the extreme pain to match the most basic components and avoid additions to the signal chain. On the other hand, I plan to audition Transparent cables on the advice of a friend. Through their extensive R&D, they may have found ways to make my system better, and that's worth listening to. Ah, and then your emotions take over... It won't make a difference, but heck let's have a listen... :-) Be strong and resist the urge, Mate... :-) Or, listen and think whether this set of cables seems to do a better job conveying the music compared to what you have. I'm not saying the particular one does or doesn't, but only listening in your own system can tell you the whole story. Of course if you know the "formula" of this cable or the circuit for that amplifier - you can build them yourself. The question is how much is it worth to you... To some people an interconnect is worth $50 max and even when they hear a better set they won't spend the money. To other people money is no object. Most of us fall somewhere in between... See - we were just reduced to an "average"... :-) But somtimes, just sometimes, the emotions take over. Like my friend that needed to rebuild his garage and one day I go to visit and he has a $40K dCS digital front-end - and no garage... The mysteries of the mind... :-( |
Pabelson: Just because you don't know the science doesn't mean the science doesn't exist Then we finally agree! You and I don't know why it sounds different. That doesn't mean it sounds the same, only that we haven't reached that level of analysis or technology. I couldn't agree more!!! |
Pabelson: But I do know why it sounds different. No, you mean you ASSUME. Based on what? Absolute self-appointed authority? It sounds different because you don't even bother to level-match before you do comparisons. Or it "sounds" different because you imagine it to sound different. That's the science you don't know. Go learn it. I'll let you level match the boombox to the main system. I'll bring my own sig gen, scope and distortion analyzer for you to do a better job. If you want, I'll calculate the Fourier transform for you on paper, how about that? Still think I don't know what I'm saying? A scientific approach is based on observations, forming a theory and then showing that the theory predicts correctly other events, not forming the "super theory" and sticking to it no matter what. Trouble is that with all that engineering knowledge I cannot ignore obvious OBSERVATIONS and you do. That's the only scientific difference, having an inquiring mind or dismissing what does not "fit our theory" based on "assumptions" like the quoted post (in its entirety - no editing). |
Pabelson: You're ignoring all the cases where people have claimed to hear differences Did I at any time claim that these "people" are right?! Let's be very clear about this: I'm only responsible for my own observations or claims and have no desire to defend someone I don't even know. |
