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Is there any way to minimize bias in a blind test when you know which speakers are playing by hearing them?

maxxevv

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#21
You'll need a microphone at your listening position to match the SPL of the different speakers too.

Note the amplifier setting of each speaker set to achieve the matching SPL. So that when you switch, the volumes are adjusted accordingly.
 
OP
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Thread Starter #22
I had this exact problem with a blind test I did with myself and a couple friends last year. I was able to pretty easily recognize the two speakers in the 1v1 blind that we did. The blind still worked for my friends, though.

My suggestion - and what I would do if I were to do it again - is to find away to introduce 2 or more new speakers into the blind that you've never heard before. Maybe use crutchfield for their $10 return shipping, or use a company that offers free returns. If you can setup a blind with say 5 speakers, 3 of which you've never heard, I think it will be much more difficult to identify the ones you know, especially if you listen to music you've never heard before.
Interesting and thanks for the suggestions. What speakers did you blind test, by the way?
 

Spocko

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#23
You might want to explore using this device if you want to spend some money ($1,100) as it is an all in one ABX test comparator device from Van Alstine. https://avahifi.com/products/abx-switch-comparator
It features:
  • Precise volume level matching, within 0.1 db, of any system.
  • Blind test modes (either informal or formal) force evaluations by how it sounds.
  • Works with or without a subwoofer.
  • Programmable power-up state and adjustable display brightness.
  • Persistent volume settings power up the same as they were when last powered down.
  • Multiple systems can be set up permanently and switched in/out with remote control.
Screen Shot 2020-03-18 at 1.53.21 PM.png

https://avahifi.com/products/abx-switch-comparator
 
OP
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Thread Starter #24
You might want to explore using this device if you want to spend some money ($1,100) as it is an all in one ABX test comparator device from Van Alstine. https://avahifi.com/products/abx-switch-comparator
It features:
  • Precise volume level matching, within 0.1 db, of any system.
  • Blind test modes (either informal or formal) force evaluations by how it sounds.
  • Works with or without a subwoofer.
  • Programmable power-up state and adjustable display brightness.
  • Persistent volume settings power up the same as they were when last powered down.
  • Multiple systems can be set up permanently and switched in/out with remote control.
View attachment 54877
https://avahifi.com/products/abx-switch-comparator
This might be a useful product if/when ASR every starts conducting blind tests.
 

aarons915

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#25
I don't think you'll know what's playing with that many speakers as long as you have someone pick 2, without you knowing which 2. The problem is you need to level-match them and since you're mixing towers with bookshelf speakers I would run the test with your high pass in place, without subs, this will reduce the influence of bass somewhat. It's also easier and simpler to just use 1 of each speaker and play the songs in mono and of course you'll need a way of instantly switching between the 2 speakers.

I would suggest comparing them almost in a playoff format, the winner stays and another speaker is brought in to challenge it, but make sure you don't know which one wins each round. Have the person make a note of which speaker was preferred to the other but you shouldn't know the results until the end.
 

NTK

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#26
I think another complication is speaker positioning. Here is a screenshot from Dr. Toole's CIRMMT lecture video. In the blind tests, the overall winner was the light gray one (third from left). However, when it was placed in the "disadvantaged" position, it was beaten by the other 3 at their "advantaged" positions. Thus, all speakers should be placed in positions that do not bias the outcome. Should they all be in the same locations when they are listened to (which will require moving speakers)? Or they be placed at their most favorable positions (which will need to be determined--another complication, and when different speakers take the same spots--a need to move speakers)?

C2.JPG
 

MattHooper

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#27
Because other speakers may damp resonances (act as a bass trap) or cause resonances when not connected to anything. Certainly when close together.
I've had a hunch that I've been experiencing that problem.

My two channel system is in the same room as my home theater, which has a surround system. My home theater sound has always been well balanced including in the bass frequencies. But lately it seemed to become quite "boomy" in a way I never experienced.

The only thing that has changed was the introduction of two JL 110E subwoofers, placed below the projection screen in between my L/C/R speakers. The subwoofers were placed there because I plan to integrate them with my 2 channel speakers (which are further out in to the room).
They are not connected or active at the moment. The only hypothesis I've had concerning the new boominess to my home theater sound is the introduction of those subwoofers - either that their drivers are resonating sympathetically and introducing bass issues and/or that their placement slightly alters room node behavious for the L/C/R speakers on either side.
 

MattHooper

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#28
I've only done one kinda blind test with speakers. Years ago a pal had a pair of Quad ESL 63s and a Spendor BC1 pair. He wanted me to do a blind shoot out. I used a blindfold and he just switched the signal between each pair of speakers (placed near one another to the sides IIRC).
It was surprisingly close once I didn't know which speaker was playing! Though ultimately I could detect the boxier character of the Spendor speaker.
 

Mnyb

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#29
I've had a hunch that I've been experiencing that problem.

My two channel system is in the same room as my home theater, which has a surround system. My home theater sound has always been well balanced including in the bass frequencies. But lately it seemed to become quite "boomy" in a way I never experienced.

The only thing that has changed was the introduction of two JL 110E subwoofers, placed below the projection screen in between my L/C/R speakers. The subwoofers were placed there because I plan to integrate them with my 2 channel speakers (which are further out in to the room).
They are not connected or active at the moment. The only hypothesis I've had concerning the new boominess to my home theater sound is the introduction of those subwoofers - either that their drivers are resonating sympathetically and introducing bass issues and/or that their placement slightly alters room node behavious for the L/C/R speakers on either side.
Would turning the subs "on" help ? maybe with the amplifier active the drivers are damped somewhat ?
 

MattHooper

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#30
Would turning the subs "on" help ? maybe with the amplifier active the drivers are damped somewhat ?
I've meant to try that (and thought I did but maybe forgot I didn't get around to it). Thanks for the reminder.
 

HammerSandwich

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#31
That should work. I've read about PA guys destroying compression diaphragms when calibrating woofers. Once they started leaving the HF amps powered up, the problems stopped.
 
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