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John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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Old 20th November 2018, 07:46 PM   #9971
scottjoplin is offline scottjoplin  Wales
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Originally Posted by john curl View Post
No, I am a disciple of Ram Dass.
Wow man, far out. Hey, have you scored any of this sonic gear Listening to These Beats Supposedly Gets You High. We Try Them | L.A. Weekly
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Old 20th November 2018, 08:21 PM   #9972
tapestryofsound is offline tapestryofsound  Scotland
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Originally Posted by gpauk View Post
Really? Why is that?
Thinking out loud, I guess it is because each and every individual has a life and history that leads up to the very moment of the ABX test, and that in itself brings with it all of the phsychological baggage and inner psychic chatter into the listening test environment.

To filter out all that 'noise' and to achieve an observable and repeatable objective result would take either a considerable number of untrained participants, or a rigorously select few of highly trained participants. Both approaches have their advantages and disadvantages.

The main disadvantage is there are relatively few individuals out there at all interested. They like the music, and don't really care all that much how it gets into the ear canal.
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Old 20th November 2018, 08:58 PM   #9973
DPH is offline DPH  United States
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^ The food guys manage to train folks fairly quickly to be at least decent, some/a lot of it coming in the form of "dry running the protocols" to gain familiarity with the selections and how the test will actually precede, which goes a long ways towards removing test anxiety(this goes for any protocol). On the other hand, there is still the mental burden of the test itself.
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Old 20th November 2018, 09:36 PM   #9974
john curl is offline john curl  United States
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Yeh, like the A-B protocols comparing New Coke and old Coke. '-)
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Old 21st November 2018, 05:22 AM   #9975
john curl is offline john curl  United States
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What happened? Did my 'coke' test reference confuse you? What I was relating to is how the managers at Coca Cola decided through some sort of tests to change 'old Coke' to 'New Coke' and then meeting a great deal of resistance from the public who actually like to drink the stuff. SO, they switched back to something close to 'old Coke' and called it 'Coke Classic' and quietly phased out 'New Coke' for all intents and purposes. Of course, they could not admit their mistake, so they double blind tested the major advocate for getting the 'old Coke' back and PROVED that that guy could not tell the difference, by getting a null in the test. Some test huh?
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Old 21st November 2018, 06:23 AM   #9976
bimo is offline bimo  Indonesia
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All sound systems sound same, although I never heard them

Just kidding
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Old 21st November 2018, 07:05 AM   #9977
PMA is offline PMA  Europe
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Originally Posted by mmerrill99 View Post

The use of some form of hidden controls, as recommended in ITU guidelines, is one possibility to ascertain is the participant sensitive to a certain level of known audible difference - for instance in one or more of the 16 trials of an ABX test, B could be an exact copy of A except that it has been adjusted by 1dB (or whatever is deemed appropriate) & if X is not identified correctly as A or B then we have an indication of false negative for this particular type of difference - does it generalize to lack of sensitivity to other small impairments? More than one trial & more than one run of ABX would be needed to evaluate the sensitivity of the participant/test to small impairments. Volume level is just one suggestion, easy to implement, to act as a hidden control - other differences are possible & other approaches have been suggested in the past
In our off line tests as they are suggested here (like my tests in "Everything Else" forum) the participants have free choice of

- volume level used
- number of trials used
- length of time interval used, one test may take 24 hours or more if the participant likes,
- number of trial repetitions
- sound system used that is familiar to the participant, headphones or speakers

So, IMO, all your suggestions are fulfilled, the participant has absolutely free choice of almost anything, no stress, he does not have to go somewhere and fulfill the protocol of the test in unknown place with unknown people.

So, taking into account this almost absolute freedom of choice and no pressure, why are there almost no positive ABX results in tests like wire x tube pre with 0.5 - 1% distortion, or even when testing the original file vs. recording through hybrid power amp with same distortion, loaded with speakers? Is it because of "stress", or for the reason that the sound differences are at the threshold of hearing resolution, hearing cleaned from sighted biases like look, brand, good highend story etc.?
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Old 21st November 2018, 07:53 AM   #9978
mmerrill99 is offline mmerrill99
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@PMA, have you ever tried to test how sensitive your test is by embedding hidden controls in it, as I suggested? Until you do you will never know if it's the test itself that is supressing people's ability to discern differences.

Btw, the first two of your choices are not free
- if people use too high a volume, differences can be audible which would be inaudible at normal listening levels
- 16 trials is the normally accepted min number for statistical significance

Last edited by mmerrill99; 21st November 2018 at 07:58 AM.
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Old 21st November 2018, 08:24 AM   #9979
vuki is offline vuki  Croatia
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How to win That Music Competition

on sighted vs blinded
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Old 21st November 2018, 08:34 AM   #9980
PMA is offline PMA  Europe
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Originally Posted by mmerrill99 View Post
@PMA, have you ever tried to test how sensitive your test is by embedding hidden controls in it, as I suggested? Until you do you will never know if it's the test itself that is supressing people's ability to discern differences.

Btw, the first two of your choices are not free
- if people use too high a volume, differences can be audible which would be inaudible at normal listening levels
- 16 trials is the normally accepted min number for statistical significance
I agree on both. Too high volume can pick up noise-only related issues. 16 trials at least, agreed.
For the reason of possible "too high volume" issue, I constituted both of my latest test to be immune to this manipulation. This is made by sample music choice, cutting no-signal beginning and ending of files and further tests and file comparing.

Regarding test to hidden controls sensitivity, IME I did what I could.
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