December 4th, 2018, 2:47 pm
mix4fix wrote:I have both cabinets, one side of drivers, and not enough mounting screw for one side.
December 4th, 2018, 2:54 pm
December 4th, 2018, 3:39 pm
December 4th, 2018, 3:49 pm
tomp wrote:Stuart:
I don't understand why you say the test was flawed unless breaking a preconceived notion that someone has about expected outcome makes it flawed in your mind.
The random selection pattern was pulled from a site on the web that mathematically determines randomness. There was no equipment between the caps under test and the speakers. If anyone would like to repeat the test I would be happy to help. BTW, you are incorrect in your memory of the results. No one including David got a result anywhere near 70%. Statistically you could have gotten the same results by flipping a coin.
As far as the caps, prior to the test there were claims that the differences in the caps were huge. As the test results showed that was not the case with no one being able to distinguish between the caps on a level beyond random. Let's do it again if you want more confidence in the test.
December 4th, 2018, 3:54 pm
December 4th, 2018, 4:29 pm
December 4th, 2018, 4:36 pm
December 4th, 2018, 5:22 pm
tomp wrote:The test conditions for the crossover cap test were as follows:
1. A set of speakers built by Stuart were used for the test that occurred in David Berning's listening room. Stuart can provide the details of the speakers.
2. The crossovers were constructed so that the capacitors under test could be swapped out in the same boards so only the caps changed.
3. No ABX box or other device was used to switch the caps in and out.
4. The choice of which caps (A or B set) would be used for each trial was determined by a random sequence generator that is on the web.
5. The values of the caps were verified so they were the same for both sets.
6. Before the blind trial, listening sessions where the cap in the speaker was known were conducted for both sets.
7. To make it a true double blind test, the person changing the caps (me) was not in the room during the listening tests so I could provide no visual or other clues as to which set I had installed.
8. With the listeners in another room I installed the set of caps determined by the random sheet and then left the room after telling them the test was ready to proceed.
9. The listeners controlled the music and length of the trial. When they were through they let me know it was time for the next test, called me back, and left the room while I either changed caps or left them the same as determined by the sheet.
10. To make sure there was no clue as to whether I changed caps by the length of time I took, in every case, I took the same time to remove the caps and installed either the same caps or the second set before calling them back so the time was the same and if anyone was listening to my actions they were the same.
At the end of the test the score sheets that were used by the listeners to determine which set of caps was used for each trial were collected and scored against the original random selection sheet from the web.
One of the legitimate complaints of the test was the necessity to leave the room between trials which interfered with their memory of the previous test. I offered to use my ABX control center which would allow instantaneous comparisons but there were some who did not want anything else in the test. BTW, I have done many sessions with listeners to determine if they could hear a difference when the ABX tester was in or out of the circuit and they could not. David Berning did not trust my tester so he built his own and achieved the same results. If anyone is interested in doing further tests either with or without the test box, let me know.
December 4th, 2018, 10:22 pm
December 4th, 2018, 10:45 pm
TubeDriver wrote:My point about effect size is that you had 3-4 listeners? Less than 10 trials? Perhaps you would need 100 listeners to reliably detect a difference? Or single listener would need to need hours and many trials? In a system they were familiar with? With so few observations, even using a random generated observation, standard error will be large. How about uncontrolled variables.....was each listener agnostic to the finding of the other listeners in real time during each evaluation period? Etc, etc etc..
I guess my point is that getting/calculating statically significance is easy but getting valid results from any experiment involving human participants is often difficult.
https://journals.plos.org/plosmedicine/ ... ed.0020124
This is an interesting publication but I think they are talking about something quite different than what we are doing. Among other things, when they talk about bias they include "manipulation in the analysis or reporting of findings" To me that means the same as cooking the books which is not what our tests entail. They also talk about the pressures of financial interests to achieve a certain outcome. That may be true in the medical arena but last time I ran a test no one was paid to achieve a certain outcome. There are other statements that either way overreach or do not pertain to the types of testing we do. I think that they left out an important assessment of testing, that being that although most testing perhaps in the medical field may be suspect, most properly and narrowly defined testing in a double blind fashion in any arena where there are no mitigating factors such as grants or money involved are extremely useful and are the foundation of reliable scientific testing.tomp wrote:The test conditions for the crossover cap test were as follows:
1. A set of speakers built by Stuart were used for the test that occurred in David Berning's listening room. Stuart can provide the details of the speakers.
2. The crossovers were constructed so that the capacitors under test could be swapped out in the same boards so only the caps changed.
3. No ABX box or other device was used to switch the caps in and out.
4. The choice of which caps (A or B set) would be used for each trial was determined by a random sequence generator that is on the web.
5. The values of the caps were verified so they were the same for both sets.
6. Before the blind trial, listening sessions where the cap in the speaker was known were conducted for both sets.
7. To make it a true double blind test, the person changing the caps (me) was not in the room during the listening tests so I could provide no visual or other clues as to which set I had installed.
8. With the listeners in another room I installed the set of caps determined by the random sheet and then left the room after telling them the test was ready to proceed.
9. The listeners controlled the music and length of the trial. When they were through they let me know it was time for the next test, called me back, and left the room while I either changed caps or left them the same as determined by the sheet.
10. To make sure there was no clue as to whether I changed caps by the length of time I took, in every case, I took the same time to remove the caps and installed either the same caps or the second set before calling them back so the time was the same and if anyone was listening to my actions they were the same.
At the end of the test the score sheets that were used by the listeners to determine which set of caps was used for each trial were collected and scored against the original random selection sheet from the web.
One of the legitimate complaints of the test was the necessity to leave the room between trials which interfered with their memory of the previous test. I offered to use my ABX control center which would allow instantaneous comparisons but there were some who did not want anything else in the test. BTW, I have done many sessions with listeners to determine if they could hear a difference when the ABX tester was in or out of the circuit and they could not. David Berning did not trust my tester so he built his own and achieved the same results. If anyone is interested in doing further tests either with or without the test box, let me know.