New Posts  All Forums:Forum Nav:

Power Cables... Really? - Page 28  

post #406 of 417

Also, five posts in a row. Nice.

 

How do you suggest I deal with the many posts, such as yours, posted to me by several different personalities, maintain separation of response and context?

 

???

post #407 of 417

Use the Multiquote button. The one with a pair of quotation marks on it. Click it on every post you want to respond to, and click the single quotation mark button on the last one.

post #408 of 417

How is it applied in an invalid way? You still haven't adequately answered that. 50% guessing is valid,

 

Sure I have.  In the case of ABX cable tests, the fifty percent, you're guessing rule is a species rule of convenience that discounts reality in that it doesn't allow for low level hearing sensitivity in that it's doesn't allow for those tests where an individual really can hear a difference but only with a dependency factor lower than fifty percent.

 

In the case of cable tests, this parameter is being applied as a matter of convenience to prove a bias.

 

...as I hoped you would have understood from my coin demonstration.

 

What makes you think I didn't understand your example?

 

???

post #409 of 417

Use the Multiquote button.

 

I'll do my best to figure this one out.  Thanks!

post #410 of 417

You're also confused as to the use of the word "reliable". Pay particular attention to definition #2,

 

2 : giving the same result on successive trials.

 

Definition #2, when used in the context that I used the word, supports my comments of a reliability factor of one in ten.

 

(Fortunately for me, oh darn, I have to go to work.)


Edited by beeman458 - 7/13/10 at 6:56am
post #411 of 417


 

Quote:
Originally Posted by Prog Rock Man View Post
Because he said this

 

"No testing of the listening ability of the subjects; no attempt to determine if the components being tested have any electronically measurable differences; no attempt to determine at what threshold a positive result can be obtained (related to the previous points) and the people performing the tests are usually extremely biased and are performing them intent on getting a negative result.  None of this is good science."

 

To clarify I am talking about the science behind blind testing in relation to audiophile claims to do with power cables in particular and cables in general.

 

Hifi Wigwam conducted a test where four power cables were disguised with the same sheathing and then set to different forum members who had about a week each to try the cables on their own kit at home. At the end eight of them said they had heard differences between the same cable, as two were identical. None reliably picked out the audiophile cable. That is a well conceived and conducted test with no press influence or deception or religiously held beliefs to somehow falsify the results.

 

Currawong speaks speculatively and as I quote "None of this is good science". I am speaking of actual testing where there is is very good science.


I'd be quite interested in a blind test of that design, but while using cables that the subjects would normally be able to do a sighted A/B differentiation under the same circumstances.  At that point, we'd have strong evidence for placebo effect with those subjects and with those cables.

 

I will not be commenting further about this since as Lenni rightfully says, we probably shouldn't be discussing DBT's here.

 

I'd normally take this up with you in the thread "Audiophile Myths and Claims", but after your comments in this post of yours, I decided to stay out for sure. 


Edited by aimlink - 7/13/10 at 7:13am
post #412 of 417

considering the length of regular wire between my audio gear, my house counter and the mains power grid...I'm not really a believer in high purity copper power cables yada yada, but shielding is very real...especially in those wifi-warfare days(I can pick up +10 networks where my gear stands[:ideenoire]).

 

so whaddayasay about ferrites on AC cables? noone seem to agree on anything of course: http://www.agoraquest.com/viewtopic.php?topic=24349&forum=65&start=0&select_page_number=1 

 I have found that when it comes to Digital equipment which is highly sensitive to RFI contamination the ferrite filtered power cords offer much better performance, but on non-Digital equipment the LAT powercord worked much better than the power cords with ferrite filtering.

I added a total of 40 more ferrite filters to MMM's various cables, interconnects, power cords, speaker cables. Remember she has 9 speakers and 6 subs so there are alot of cables. The effects have been positive without any detecable loss of dynamics. In fact there seems to be an improvement in that area due to less noise.

http://www.venhaus1.com/diymains.html

I have found that Ferrites constrict the dynamics of the system and they ADD inductance to the hot/neutral

 

some say that ferrite filtering gives a "blacker" background, and others that all it does is destroying the sine waves...but the ferrites I use only add impedance >25Mhz: http://vendor.parker.com/Groups/Seal/Divisions/Chomerics/Chomerics%20Product%20Library.nsf/24eb4985905ece34852569580074557a/9cd8138d75093bd08525699d00460881/$FILE/chosorb.pdf

 

regular ferrites can destroy a TMDS signal, though(but AC is 50/60Hz): http://www.scapro.se/text/murataemidvi.pdf

 

A major issue is that the addition of an EMI filter, for example, can cause waveforms to lose their shape, making faithful data transmission impossible. [..]
DVI transmission rates are in excess of 1.6Gbps, and if ferrite beads are added to signal lines, not only is the extraneous noise component eliminated, but also the frequency components that make up the signals to be transmitted!

 

TDK sell ferrites specifically aimed at filtering TMDS signals.


Edited by leeperry - 7/13/10 at 11:02am
post #413 of 417

Show Don't Tell

 

On my random play this morning...
 

post #414 of 417

... There is so much wrong with this post that it's almost difficult to reply to, so I'll try to take things point by point in the italicized text.
 

Quote:
Originally Posted by beeman458 View Post

 

Smart people realize that DBT prove absolutely nothing other than the test giver arbitrarily discounts anything they haven't heard themselves.

 

No. Just no. Double-blind testing is double-blind when neither the subject nor the test giver know which item is which during the test. It only records the data generated by the subject while attempting to eliminate experimenter bias. That's the whole *point* of DBT. For that matter, one would think that "smart people" would actually know what DBT involves...

 

How can anybody, with a straight face, declare that something can't be heard by another.

 

"I'm sorry, you didn't hear what you just heard because if you don't hear it often enough to suit my statistical purposes, I'm here to tell you, that you didn't hear what you heard."

 

There's no attempt to tell you what you did or did not hear, only if you can hear what you claim to hear and tell the difference more frequently than you would while randomly guessing. If you can actually hear what you claim, it's likely that you would be doing better than random guessing.

 

Or.......

 

"I'm sorry, you didn't reliably hear it often enough to count, so I'm going personally declare you didn't hear what you say you heard because I know better."

 

Even the medical field gets a better pass than fifty percent.

 

"This drug may work only ten percent of the time but using this drug enhances your survival rate from zero percent to ten percent."

 

... That's not how statistics work. That "50%" is how frequently you'd likely to guess correctly between two options purely by chance. Again, one would think that you'd do better than random chance if you can actually hear a difference. Your comparison is invalid as in that scenario (beyond the fact that it's a downright unrealistic scenario), 0% *is* the frequency prior to treatment, and is comparable to the 50% in the case of two different cables. But again, it's an unrealistic scenario and a poor comparison in the first place, so even that's a bit of a stretch.

 

I'd like to see one of these anti-cable testers turn this treatment down because it doesn't serve their seventy or eighty percent rule.  You really do need to look past the BS of these test givers and once you're on to their BS, it's wisdom, not aversion that stops one from being foolish enough to take a meaningless test designed to ensure fail.

 

There's no debate here.  Why?  The dice are loaded in the favor of the house.  Who wants to play in this casino?

 

Unfortunately, this is just going to have to come as an appeal to common sense. In an earlier post, you discuss someone reliably hearing a difference 10% of the time. This is another poor example, but I'll try to work with it. If you're saying that such a person would be able to correctly guess which cable is which only 10% of the time, it's laughable. That would be significantly worse than even random guessing at 50%, and there's no way to really read anything into it other than "Wow, this guy happened to guess really poorly." The only other way I can think to use that 10% is if you mean "10% improvement over chance." in which case you'd have to be just a little over that 50% which you seem to find so unreasonable. Bring that up to 20% or so improvement over the 50% and it starts getting statistically relevant. However, I think we'd also all have to agree that when differences between cables are expressed as "night and day" or "lifting a veil," one would expect just a *little* more than "a little better than random guessing."

And please, make sure that you actually have a well formulated argument before attempting to insult the intelligence of anyone who doesn't happen to agree with you. One can have a viable argument and disagree with the methodology of a specific test. To claim that all double-blind testing is invalid, however, is nothing more than foolish. And if you do find a valid problem with the methodology of the tests that have been performed, by all means point it out and propose an alternative test. You'll find that the "anti-cablers" you refer to are really just proponents of empirical evidence, and would welcome further testing even if the results don't agree with them.

post #415 of 417

Did you feel that cool breeze waft in here? It was a few of posts ago I think...  

post #416 of 417

All I feel in this thread is a warm breeze that smells of poopoo... 
 

Quote:
Originally Posted by Rdr. Seraphim View Post

Did you feel that cool breeze waft in here? It was a few of posts ago I think...  

post #417 of 417

This is a DBT free forum.  This thread is locked until it can be cleaned up.  If you want to have a DBT discussion, please do so in the Sound Science forum.  If you can't follow the rules with posting here, you're basically asking to not be allowed to post at all.  Your choice.

New Posts  All Forums:Forum Nav:
This thread is locked