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Phase cancellation between 50-75 Hz
Old 3 weeks ago
  #1
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Avgatzeblouz's Avatar
Phase cancellation between 50-75 Hz

Hi everyone,
I'm re-positionning my speakers in my room, as some work has been done in it. The room has some basic bass trapping helping quite nicely in the 100 Hz area. The issue I faced today is the following : I moved my left speaker, and did measurements until I found the best spot in the room for the speaker and the measurement mic. I had a pretty nice curve, with only 7-9 dBs variations across 40Hz-12kHz. I then put my right speaker symmetrically in the room, and measure. Good response, even though not as good. I measure both of them... Gigantic hole from 50Hz to 75Hz ! I superimposed both curves, and they show the responses are out of phase from 45 Hz to 75 Hz ! I tried with other speakers, passive ones, and the same result occurs, so improper woofer wiring is not the cause.
So this was the best spot for individual speakers, and I face this very frustrating issue. I tried to move the right speaker closer to the left one, and the phase cancellation disappears after around 20-30 inches to the left, but the overall response is not as good, and I find myself uncentered in the room.
Does anyone have any advice on how to remedy to this situation ?

Thanks, guys.
Attached Thumbnails
Phase cancellation between 50-75 Hz-basses-hors-phase.jpg  
Old 2 weeks ago
  #2
Lives for gear
 

well, it's all about the combined response...

anyway, the graph doesn't look very nice at 50, 100 and ca. 120hz etc. very well either - assuming you have ruled out any anomalities and differences in the entire monitoring chain in both channels, issues could stem from the distance between the woofers and/or to any of the walls:

you get max. phase offset between two speakers at half the distance of the wavelength and additional boundaries (table, desk etc.) can also lead to issues.
so, remove all gear other than the speakers to find out about the latter. if you're using the speakers in landscape mode, swap their positions (to change the distance between lf woofers) and you should see an improvement - besides getting you the lowest octave (which seems to be missing), a sub could also help to smooth out the fr.
Old 2 weeks ago
  #3
Lives for gear
What about Waterfall?
Old 2 weeks ago
  #4
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Avgatzeblouz's Avatar
I gave up for now, and put back my Spiral groove. The curves are not really good, but I guess making the bass traps deeper will help. It is still better than this gigantic hole the phase cancellation was making. I'll work on that, thanks for your help !
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