[liamstrain]

Quote:

 
Different dielectrics have different permittivity which is pretty important in determining the capacitance of the finished cable.
 
That said you actually have to try pretty hard to cram enough capacitance into a short cable to bother a decent amplifier.  Of course there are some amps out there that are already borderline unstable and might actually sound different with varying, but reasonable to expect, amounts of cable capacitance.

 
Thanks for the clarification - I forgot that the overall cable capacitance is affected. But you'd have to screw up a good bit, to get it high enough to mess with the high frequencies...especially if you were already designing for low cap.

 

[maverickronin]

Quote:

Thanks for the clarification - I forgot that the overall cable capacitance is affected. But you'd have to screw up a good bit, to get it high enough to mess with the high frequencies...especially if you were already designing for low cap.

 
It's possible to get some amazingly high capacitance if you manage to do everything wrong.  Using something with a poor dielectric constant/relative permittivity like silicone rubber, with some multi-stranded fancy looking braid, and then hooking it up to an amp with a high output impedance you could probably make a low pass somewhere in the audible range.
 
I was talking about how a poorly designed amp circuit could go into some kind of oscillation based on the capacitance of the attached cable and then rain down extra distortion products into the audible range which is a different mechanism.  That would make the cables sound different, but only because the amp driving it is essentially defective.

 

[liamstrain]

Ah - I see what you are after. Makes sense. 

 

[arcticears]

Quote:

+1.
Most cables from $20 to $2000 fall within 'reasonable limits', and it is perfectly possible to screw up the signal and it will affect the sound. Just that the $20 cable won't sound that different from the $2000 one if they are not screwing up.

Correct, I did not mean to imply that the difference would be any more than noticeable if that, certainly not enough to justify the expense.

 

[jnjn]

Quote:

@jnjn
 
Yes, L, R, C are the important factors in a speaker or headphone cable and as long they are kept within reasonable limits the cable should work fine.  It is possible to make a cable which sounds different if you screw things up enough, you have to try hard though.  A good link on speaker cables and effects of L, R, C on them can be found at http://sound.westhost.com/cable-z.htm. 

Rod's a nice guy.  Unfortunately, some of the content is not correct.
 
1.  His loudspeaker model is not reality.  Close enough for a lot of work, but lacking frequency dependent resistance.  When a coil of wire has dc current flowing, the cross sectional current density is uniform, the resistance of the wire will be that of the wire off the coil.  When you start to increase the frequency of the current, proximity effect will rear it's ugly head.  This effect (a consequence of maxwell's equations) causes the current to use less of the conductor.  When this happens, the effective resistance of the coil will increase.  Nowhere in the model is this effect considered.  And, it is not a small effect.  ALSO not present is anything which represents eddy currents.  All metals, when subjected to time varying magnetic fields, will produce internal currents which fight the intrusion of the external time varying fields.  The magnetic structure of any electrodynamic driver will do this, using ferrite or laminations are two good ways to reduce this effect.  So, as a linear lossless model, it's great.  But it's not reality.  edit:  BTW, when modelling and testing an inductor, I typically use the Rs/Ls model. From the end terminals, the proximity and eddy current losses show up as an increase in the series resistance.  In fact, any losses in the inductor show up as an increase in Rs.  This applies for phono carts all the way up to the ITER central solenoid for fusion initiation (4 meters diameter and 13 meters tall.
 
2.  His t-line discussion is terribly inaccurate, misleading, and should be changed..
 
Quote:

OK. I'd argue that discernible and audible are two different things in this case, being that I'm not sure in what qualifiable way this effect changes the sound itself or what variations in delay are seen as acceptable in common comparison testing. I'm also curious to find out whether this discernment is the result of neural processing of interaural differences. Looking forward to reading Nordmark's work.

Nobody is.   The connection has been studied in the field of neuro, but there is no formal education on it available to audio engineers.
 
Hmm, not sure how to call it...Neural processing of Interaural differences? chicken and egg?
Quote:

 
Yes I agree with the L C R componant making a difference & largely only that making the difference though in one case though unfortunately I didn't have the equipment to test the capacitance of the cable at the time but that was one cable that I'm not sure why but it sounded absolutely horrible. It went by the wayside in less than a day it sounded so bad. None of the other cable I tried sounded remotely that horrible. I have never head even high capacitance cables sound that bad. I do believe it was the properties of the dielectric in this case. Perhaps a really bad batch of it. Do to the L C R properties of commercially available cables being not as low as I needed when I was running a passive preamp I made my own cable that were super low in capactance (about 75pf for  meter with ends) 7 these cable were superior sonding to the commercial cable in my aplication. I continue to make my own cable for high output impedance devices as my cable just couldn't be beat in that application. In low output impedance or matched output impedance to the cable characteristic impedance I found there to be no difference as there shouldn't be.
 
By the way my cable are very very cheap to make. The costliest part of them are the ends which I get for around 20 dollars for the ends sufficient for one stereo pair of cables so you see I don't elieve in expensive cable either.

Are these headphone cords or interconnects?
Quote:

 
Different dielectrics have different permittivity which is pretty important in determining the capacitance of the finished cable.
 
That said you actually have to try pretty hard to cram enough capacitance into a short cable to bother a decent amplifier.  Of course there are some amps out there that are already borderline unstable and might actually sound different with varying, but reasonable to expect, amounts of cable capacitance.

When making a cable, the following equation applies.
 
LC = 1034* EDC
 
L is inductance in nanohenries per foot
C is capacitance in picofarads per foot
EDC is the effective dielectric permittivityof the geometrical construction. For a constrained cable design, this is equal to the relative dielectric permittivity of the insulator.  For an unconstrained cable design, this is the lower limit of what can be built, actual cables will be higher.
 
A constrained cable is designed for little external magnetic field.  Coax is one, high count braid where return and send intermingle, ribbons against each other where the insulator is more than ten times wider than thick.
 
Typical dielectrics not foamed have a value about 3.  Foamed runs 1.05 to 1.5
Typical zip cords run from 4 to about 10 EDC.
 
If you have vendor numbers for L and C, use this equation to calculate the EDC.  If the EDC is less than 1, one or both of the values is incorrect.  EDC less than 1 is superluminal propagation velocity, so unless the vendor has a nobel prize, it ain't happening.  The prop velocity of a cable is 1/sqr(EDC).  If EDC is 4, velocity is half lightspeed.
 
This is a consequence of the amplifier's open loop unity gain fequency and how the load decouples as frequency goes up.  A high capacitance cable will NOT look like a capacitor as long as the load retains an impedance close to the cable.  Once the load decouples, the energy storage of the cable will look more and more like capacitance, and the phase shift will marginalize the output..it'll oscillate.
 
j

 

[arcticears]

@jnjn
 
Thanks, again you make me think.  In the post, he does state he is using a simplified equation.  While not  giving the "whole" picture, do you not agree that for cables used in for audio frequencies, that it gives usable information?  As for T-lines, I will dig a little deeper.
 

 

[jnjn]

Quote:

@jnjn
 
Thanks, again you make me think.  In the post, he does state he is using a simplified equation.  While not  giving the "whole" picture, do you not agree that for cables used in for audio frequencies, that it gives usable information?  As for T-lines, I will dig a little deeper.
 

Yes, what he presents is very useful.  It is great for the first pass when analyzing the system.  The concern of imaging, soundfield recreation, and localization/lateralization is beyond the scope of the simplified or approximation equations.  As I stated earlier, I never even thought we were able to discern much below 50 uSec, nevermind 5 or even 1.2.. 
 
We are taught the approximations simply because if we used the analytically accurate equations, nobody would get anything done.  Imagine trying to hash out bessel solutions for skin depth??  I couldn't...so I use the exponential approximation for basic calculations, but understand it represents a simplification.  Should a problem require deeper analysis that the exponential provides, I can at least understand the limitations.
 
T-lines are very difficult to really understand if you have been taught the approximations and use them.  Sometimes you have to stand back and re-analyze.  Once I realized the issues concerning the line to load imbalance (as well as experience with 400 volt per nanosecond hardware build and use), I sat back and worked out the problems caused by using approximations and rule of thumbs.
 
Let me know if you have any questions, I'll answer what I can.
 
j

 

[arcticears]

@jnjn
 
Thanks, what you say in true about all approximations, they should only be used if you keep their limitations in mind.  I am still digging on the T-line thing.
 

 

[germanium]

To your question jnjn,Are these headphone cords or interconnects?
 
I was speaking of interconnects as headphone amps have low enough output impedance to make the cable capacitance of no consequence though if you go to low of output impedance you could get problems with oscillation on poorly designed amps with high capcitance cables. It could also cause some problems for wide band amps which are already on the verge of oscillation with normal loading

 

[kiteki]

Originally Posted by jnjn /img/forum/go_quote.gif
 
You have provided a very astute observation here, well done. 
 
j

 
Thanks, and thanks for the civilised comments.
 
 

Originally Posted by Prog Rock Man /img/forum/go_quote.gif
 
I agree that further testing of those who do make correct identifications is needed. Further testing is needed to see if there really are golden ears who can reliably pick out which system is which.

 
Then you should add a note in your compilation thread that the test was limited or flawed, right?  My issue is with studies like that one being linked to over and over as evidence, for example at places like the NwAv blog or Wikipedia.
 
 

Originally Posted by Prog Rock Man /img/forum/go_quote.gif
 
Yes, I agree the expectation is it will be as easy in blind testing to pick out differences found in sighted. People get a big shock when that does not happen.

 
Nothing in the study mentioned sighted differences, the NwAv blog has said audiophile differences disappear "when you throw a sheet over the rig" and provided that study as evidence.
 
So, where does the study mention sighted differences?  If they sound the same with a sheet over them they'll sound the same without a sheet, isn't that more sensical?  The study doesn't mention which component is supposed to sound better either, and for what reason.  Are they saying the expensive CD rack was actually supposed to sound better than the wooden chair, or... are you saying that the CD rack does or could sound better to some people when sighted?
 
 

Your hunch runs contrary to the obvious conclusion. You've found that people who are familiar with cable DBT results refer to the evidence as voluminous and one-sided, but your personal bias leads you to offer the alternative hypothesis is that there really aren't that many such tests and that most of them are flawed. This is pseudoskepticism.

If you're wondering about all these countless tests, take my previous advice in this thread and go to a library and look them up in a database (otherwise, some links don't come cheap). There you will find properly designed and peer reviewed DBTs accompanied by thorough statistical analyses. Sticking to internet-only sources puts you at a disadvantage. Not only that, but it sometimes comes across like you're asking others to do all the research legwork for you and claiming that they're wrong if they don't.

 
I don't have any desire to support fake science or flawed studies only since they refer to what's labelled by some as an "obvious conclusion".  Such labels are derived from personal opinion, intuition or scientific theory, in this case it seems not listening tests or statistical evidence.  Ill-quoting flawed statistical evidence only makes the scientific viewpoint look too narrow or like wishful thinking.
 
Perhaps with cables it's not so vital and you want to call it pseudo-skepticism, but it's clear that people with a certain attitude towards cables will most likely have a similar attitude towards all other audio components as well, even if those components are more advanced.
 
If someone says cables have been disproven with a huge body of statistics, and ill-quote papers, then when they say something like all DAC's sound the same or all microphones above $1000 are snake-oil I have no scientific reason to believe them in that instance either.
 
 
The link you provided is an article from 1987, the preview goes into a lot of detail about the vinyl rig and electrostatic speakers, however it says nothing about the cables or number of listeners in the test, it did say they think ABAB versus AAAA could be more accurate than ABX though, which I definitely think could be true in some cases and I'd like to see a Foobar plug-in supporting that testing method, or similar same-different method.
 
Is there any evidence that rapid switching ABX is the best method?  No, and please don't say it's hidden somewhere in a library and "sticking to internet-only sources puts you at a disadvantage".
 
This is the information age and information is free, you can't say locked university vaults have proven this or that. =)
 
p.s. If you think the audio field is full of people making millions on $500 Beats headphones and EE / AE's saying the CD format is statistically / scientifically proven as 100% transparent, then imagine what other fields like history must be like!

 

[liamstrain]

Quote:

 
Is there any evidence that rapid switching ABX is the best method?

 
Is there evidence that rapid switching ABX is the only kind of ABX we are recommending? I have no problem with more flexible test formats to allow for more natural listening. 

 

[Prog Rock Man]

Kiteki.
 
I do not think that since no tests have progressed to further test those who 'passed' means they can be described as limited or flawed. The reason for that is the proliferation of such tests all getting the same results. Past results show that taking the 10 who 'passed' will result in another random 'passes' and you could go on until you had just the one who has 'passed' then all. But now prove that is nothing more than random itself.
 
I was comparing the general results of blind to sighted tests when I said "differences found in sighted tests", not that one test. There are thousands of sighted test result, just read What Hifi for dozens each month into all sorts of hifi products from cables to speakers. My research into blind testing has found two results
 
1 - a very consistent outcome whereby sighted finds the differences, blind comparison finds differences which are now smaller than before and are not dependent on the price/image of the product (so cheap can do as well as if not out perform expensive) and ABX where the differences vanish.
 
2 - that different parts of the hifi chain perform differently. So no cable has ever passed an ABX test and they do badly in blind comparison, amps get mixed results, bit rates do better again and speakers do best of all in both blind comparison and ABX tests.
 
The clear conclusion is spend your money on speakers/headphones and not on cables.
 
With regards to quick and slow changes with ABX, the various tests find no difference at all. The results are the same no matter how quickly or slowly you change cables.

 

[kiteki]

Hmm the quote system isn't working right now.
 
"liamstrain - Is there evidence that rapid switching ABX is the only kind of ABX we are recommending? I have no problem with more flexible test formats to allow for more natural listening."
 
Not anyone in this thread I think, sorry if it came across like that, but I think I've seen at least one person insist on a volume-matched 0.1 second rapid switch ABX format for detecting differences in their amplifier versus more upmarket ones, or a modified version of the same amp.
 
I think rapid switching ABX is very likely the best method for detecting minor differences in volume, but it seems dangerous to extrapolate on that to all perceivable sonics.  As a sensory analogy, if you rapid switched between two different perfumes, you could be tricked into perceiving them as the same, while if you took a very quick break or smelled coffee inbetween perfume A and perfume B, you could more correctly identify the subtle differences.  If you took a 10 minute break, they could smell different due to the more typical reasons like expectation bias via visual impact, price, etc.
 
 
"Prog Rock Man - Past results show that taking the 10 who 'passed' will result in another random 'passes' and you could go on until you had just the one who has 'passed' then all. But now prove that is nothing more than random itself."
 
You can't incorporate previous test results into future tests.  You can assume the 10 who passed were only guessing, but that is purely an assumption and not statistics or science.
 
Let alone one of those 10 who passed might have said "wow system A sounded so good!" when he left the room, or pointed violently at the left system while in the room, influencing others to choose the left system.  If it dispelled some myths about super expensive audiophile CD players and CD racks not introducing very audible differences, then OK that's fine, but I still view the test as a novelty...
 
"There are thousands of sighted test result, just read What Hifi for dozens each month into all sorts of hifi products from cables to speakers."
 
I see your point there.  I'm not familiar with What HiFi, but perhaps they can't hear the differences?, i.e. they're just fabricating them for other incentives like profit, or suffering from the visual impact, price, or other emotional influences...
 
If you think more reviews should be conducted blind without having any idea what the product is, I have no issues there at all!  I think most people have decided if they like the car or not before they've turned the engine on, and someone decided audio should be all expensive leather and chrome too, not just sound.  So, some people think audio is mostly just expensive leather and chrome, which isn't true!
 
"2 - that different parts of the hifi chain perform differently. So no cable has ever passed an ABX test and they do badly in blind comparison, amps get mixed results, bit rates do better again and speakers do best of all in both blind comparison and ABX tests."
 
bit rates do well because their digital nature makes them convinient to ABX, unlike physical components, people can practice bit rates and eventually find the differences.
 
There are people (like myself) which have a hard time with ABX'ing bit rates, and Wikipedia says that 256kbps MP2 is 100% transparent, i.e. no one can hear the difference versus CD quality, proven by extensive blind-testing, actually they write "in the most critical conditions ever implemented" - http://en.wikipedia.org/wiki/MPEG-1#Quality
 
I think the ABX study they're referring to involved 61 listeners with something like 20,000 trials, in the end only 1 of them could detect a difference, that should underline that you can't collect the data and dismiss the positive results.
 
Another case in point, Wikipedia says more and more people now prefer MP3 compression to lossless - http://en.wikipedia.org/wiki/MP3#Audio_quality, which means you can't dismiss preference.
 
The Pras & Gustavino study took that into account.  Basically, some subjects kept selecting the wrong answer with such significance, that it becomes statistically significant, like losing money at a roulette table until it reaches a 1/1000 chance of losing with such significance.  Most studies don't take that into account. 
 
 
"The clear conclusion is spend your money on speakers/headphones and not on cables."
 
Yes.

 

[anetode]

I don't have any desire to support fake science or flawed studies only since they refer to what's labelled by some as an "obvious conclusion".  Such labels are derived from personal opinion, intuition or scientific theory, in this case it seems not listening tests or statistical evidence.  Ill-quoting flawed statistical evidence only makes the scientific viewpoint look too narrow or like wishful thinking.

Perhaps with cables it's not so vital and you want to call it pseudo-skepticism, but it's clear that people with a certain attitude towards cables will most likely have a similar attitude towards all other audio components as well, even if those components are more advanced.

I did not mean "obvious conclusion" in the way that you took it. The statement referred to obvious in the Occam's Razor sense, as the simplest conclusion rather than one which is correct by necessity. What I was saying is that you conclusions were more complicated than need be because of several predispositions. As in, give a man a pile of bricks and tell him to build a chimney. One man, the common laborer who has to move on to the next project, will be more economical and use just enough bricks to construct something functional and structurally sound. A different man, taking this as a leisure project, will use more bricks and embellish his way to a beautiful chimney, but without the experience of the laborer he might compromise on the structural stability for aesthetics. This analogy is meant to apply to your approach to considering studies. You're applying too much philosophy (waxing about attitudes and such), too many preconceptions, which mean that you are trying to come up with a solution that you can admire rather than just accept. Hence why I refer to your approach as pseudo-skepticism.

If someone says cables have been disproven with a huge body of statistics, and ill-quote papers, then when they say something like all DAC's sound the same or all microphones above $1000 are snake-oil I have no scientific reason to believe them in that instance either.

Perfect example of the above. How do you know that they are ill-quoting papers? Why are you extending something they say about one subject, i.e. cables, to others, like DACs or mics? And finally, why do you refer to your subsequent distrust as being prompted by "scientific reason" when it is nothing more than methodological snobbery (at best, or a deeper ideological prejudice at worst)?

The link you provided is an article from 1987, the preview goes into a lot of detail about the vinyl rig and electrostatic speakers, however it says nothing about the cables or number of listeners in the test, it did say they think ABAB versus AAAA could be more accurate than ABX though, which I definitely think could be true in some cases and I'd like to see a Foobar plug-in supporting that testing method, or similar same-different method.

Which is why my point was that you'd need more than a free online preview

Is there any evidence that rapid switching ABX is the best method?  No, and please don't say it's hidden somewhere in a library and "sticking to internet-only sources puts you at a disadvantage".

This is the information age and information is free, you can't say locked university vaults have proven this or that. =)

On the contrary, librarians take great care to arrange information for maximum ease of accessibility in libraries, it is the internet which obscures useful info with piles of random crap. As for your second point, I refer you to the other part of the oft quoted maxim by Steward Brand that "information wants to be free":

"On the one hand information wants to be expensive, because it's so valuable. The right information in the right place just changes your life. "

Good info is worth spending money and effort on, just like good music. Please don't take my suggestion to look beyond internet sources as evidence of some sort of ivory tower elitism, I'm also a huge wikinerd. And, like most other wikinerds, I eagerly admit that most online info, as mirrored by most wikipedia info, is unverifiable tripe.

 

[kiteki]

I'll answer that post later, not sure if serious or not.
 
p.s. in post #585 you said I "want others to do all the legwork" (?)  I just look at the studies which are presented as science and evidence, and check if that holds true.
 
If you have found "properly designed and peer reviewed DBTs accompanied by thorough statistical analyses" at your local library no one is stopping you from sharing it with us.