Hi all,
I have a puzzling phase issue that is deteriorating the spaciousness and envelopment of the audio system in a dedicated listening room, and I'm interested in hearing any thoughts on what may be happening. I made a series of changes to my room and I can't pin down exactly when the issue began occurring, but after putting new seating in the room that replaced giant bean bag chairs I have a phase issue with the right channel.
Previously I was able to get mono pink noise played out of phase to be completely diffuse across the entire spectrum and music was spacious and enveloping. Lately I've been noticing that music is less spacious, and when I checked mono-out-of-phase pink noise there's a notable amount of sound that isn't diffuse across the spectrum.
With all room correction disengaged I took phase measurements of the left and right speakers at the mouth of each JBL M2 horn. Single-channel phase measurements were then taken at the listening position with the mic acoustically time aligned between the speakers (the speakers should be very nearly symmetrical in the room as well). The close mic phase response between the speakers has very good agreement, but at the listening position the right channel has a lot more phase variation. This phase variation is shown by both OmniMic and Trinnov, whereas previously the phase responses matched at the listening position.
Left channel phase at horn mouth:
Right channel phase at horn mouth:
Left channel phase measured at MLP:
Right channel phase measured at MLP (consistent with left channel until ~900HZ, then greater variability):
Questions popping into my head as I type this include:
Is the right speaker level and in position, or did it get bumped during the furniture install?
Diffraction effects from inconsistent toe-in; again is it out of position?
Could this be caused by a visually imperceptible difference in asymmetry of the newly installed leather seating?
Any ideas?
Many thanks in advance!
I have a puzzling phase issue that is deteriorating the spaciousness and envelopment of the audio system in a dedicated listening room, and I'm interested in hearing any thoughts on what may be happening. I made a series of changes to my room and I can't pin down exactly when the issue began occurring, but after putting new seating in the room that replaced giant bean bag chairs I have a phase issue with the right channel.
Previously I was able to get mono pink noise played out of phase to be completely diffuse across the entire spectrum and music was spacious and enveloping. Lately I've been noticing that music is less spacious, and when I checked mono-out-of-phase pink noise there's a notable amount of sound that isn't diffuse across the spectrum.
With all room correction disengaged I took phase measurements of the left and right speakers at the mouth of each JBL M2 horn. Single-channel phase measurements were then taken at the listening position with the mic acoustically time aligned between the speakers (the speakers should be very nearly symmetrical in the room as well). The close mic phase response between the speakers has very good agreement, but at the listening position the right channel has a lot more phase variation. This phase variation is shown by both OmniMic and Trinnov, whereas previously the phase responses matched at the listening position.
Left channel phase at horn mouth:
Right channel phase at horn mouth:
Left channel phase measured at MLP:
Right channel phase measured at MLP (consistent with left channel until ~900HZ, then greater variability):
Questions popping into my head as I type this include:
Is the right speaker level and in position, or did it get bumped during the furniture install?
Diffraction effects from inconsistent toe-in; again is it out of position?
Could this be caused by a visually imperceptible difference in asymmetry of the newly installed leather seating?
Any ideas?
Many thanks in advance!
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