|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
206.255.211.134
In Reply to: RE: Exactly posted by tomservo on June 21, 2010 at 14:25:37
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
Follow Ups:
“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
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: