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In Reply to: RE: Not responsive.. posted by tomservo on June 21, 2010 at 08:56:27
>In the testing I described, all the participants had a chance to get used to their wires, had a chance to pick out the best, most revealing music passages, were all accustomed to whatever changes if any the switcher caused and could still “hear” their wires clearly when they said they were ready (to be “blinded by science” or rather having the knowledge of which was which was eliminated leaving only the aural inputs).<
Sounds like a DBT-within-a-DBT is needed. Or maybe a "bias-cure-within-a-bias-cure", would be better stated. :)
Follow Ups:
...were all accustomed to whatever changes if any the switcher caused
The only way that would be possible is to compare listening through the switch to listening without the switch and extra cabling. The box is used or it is not. That would be the necessary control to replace the assumption set.
His main point is that folks tend to focus on visual cues. If proving that was the objective of the test, then it succeeded. If the objective, however, was to objectively compare the signal wires, then it failed.
rw
"The only way that would be possible is to compare listening through the switch to listening without the switch and extra cabling. The box is used or it is not. That would be the necessary control to replace the assumption set."
Alternately, if one were to assert that covering a cable with magic marker changed it, one is stuck either measuring the effect from the standpoint of electronic theory OR by asking if anyone hears any difference.
The electronic theory approach used to design things says if the effects are small enough, they will not be detectable, the idea with the switcher is that to do this test one must compare so what matters is the stray elements are very small as they were (like a few inches of cable).
The point is that once no one knew which was which, the differences that they heard went away, that part was a blind test, if you really can't tell which is which or a difference between A and B using only your ears, the differences are very small..
The usefulness was in showing everyone just how large even dominating what they expect or know was relative to the actual / detectable acoustic changes the different speaker cables imparted relative to zip cord.
That part was huge, totally unexpected and humbling for some who were totally "sure" about their cables.
One can debate everything makes a difference even a flyspeck of dust in the room and it does at some level, but until one removes prior knowledge from the test, one is not measuring what your ears hear but an opinion which encompasses what you know and believe as well..
The point is that once no one knew which was which, the differences that they heard went away, that part was a blind test, if you really can't tell which is which or a difference between A and B using only your ears, the differences are very small..
Do you have any interest with pursuing the differences that are found with cabling? Do you honestly think that Wal-Mart zip cord is indistinguishable from Nordost Odin on a superlative system? What is your initial bias?
That part was huge, totally unexpected and humbling for some who were totally "sure" about their cables.
Once you've made the unproven assumption that loading the amplifier with both cables using the box had no effect. Who knows - perhaps the cables tested were no better than zip cord in the test system. BTW, what was the test system? Could others duplicate your test for verification? I use low DC cables because electrostats are more sensitive to both C and L. Others are not.
...but until one removes prior knowledge from the test, one is not measuring what your ears hear but an opinion which encompasses what you know and believe as well.
Do you think this concept is under debate?
rw
“Who knows - perhaps the cables tested were no better than zip cord in the test system. BTW, what was the test system? Could others duplicate your test for verification? I use low DC cables because electrostats are more sensitive to both C and L. Others are not.”
First, I understand your skepticism. Second, in particular electrostatic speakers require a low inductance as a capacitive load will form a second order low pass filter. Understand, I am not saying cables do nothing, they do something to be sure and what they do is in part related to the length.
I have a tower I use to measure speakers up in the air so that there are no significant reflections into the bass range. I need to do this in order to design the crossovers I use which do not result in phase shift, the result being something like a full range ESS, not spreading a signal out in time.
A hundred feet of good mic cable is no real problem but a hundred feet of speaker cable is a real problem. I need to have the measurement error it adds to be very small even at 100 feet. I evaluated all the likely choices but none had low enough series L, normal extension cord would produce an error/ roll off of 2 dB at 20KHz with accordant phase shift, TOO large.
I ended up making a cable from a pair of low loss coax cables (a variant of RG-9913) cross coupled.
That 100 foot cable pair ended up having the L and C in the range of the 10 foot kimber cable sample I had while having about 1/8 the Rdc. If you want to try a theoretically blameless cable, the stuff (the modern low loss RG-8’s extended family) is dirt cheap compared to audio hose, the electrical parameters are very good, the design scientific.
If you have a ham fest locally, you can pick up usable lengths of this stuff for a few bucks, look for the stranded center conductor which is more flexible.
I have a tower...
Was the speaker cable test using the box conducted with the speakers on the tower with 100' of run for each cable?
rw
"Was the speaker cable test using the box conducted with the speakers on the tower with 100' of run for each cable?"
No, for the listening tests, the cables were what the attendees brought and varied from 10 feet to about 30 feet (10 meters i would guess)in length.
For the measurement set up, each cable type was measured open and close circuit to determine the series L, R and parallel C, ALL of these properties are directly proportional to the length so one the values 'per foot" are determined, then the effect of any length out to about 1/8 wavelength can be calculated. At 20KHz, 1/8 wl is still well over a mile so there is no transmission line effect to be concerned with in audio cables normally..
Interestingly, one cable type was significantly worse than lamp cord, that was the generic round hardware store extension cord. It has much more space between conductors and so had by far the highest inductance per foot.
That series inductance can only exist when there is uncoupled flux between the two conductors (which carry equal but opposing currents), the self shielding of the coax apraoach or the weaving (and extension of twisted pair) greatly reduces the un-coupled flux which is why these types have low series L.
Best,
Tom
with the last post was to ascertain your test system to be able to put it into context. Source. Amplification. Speakers. Program material. Cabling not under comparison.For the measurement set up...
Was that done first without box and then WITH BOX and other cable(s) connected?
I was more interested with actual measurements, not calculated values in a vacuum.
rw
Edits: 06/22/10
> His main point is that folks tend to focus on visual cues. If proving that was the objective of the test, then it succeeded. If the objective, however, was to objectively compare the signal wires, then it failed. <
Precisely.
I'm not against blind testing at all. I'm not even against double blind if it can be pulled off properly, and not even against the box if it can be proven that it works as advertised. In other words, I'd like that same stuff I get asked for repeatedly... evidence.
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