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For a while now I've been noticing that I can get pretty different LF in-room response depending on current room layout and whether doors/windows are open or closed. Anyway, a couple of days ago I decided to test a few variants to see what is the impact exactly on both my systems.
First the living room system (listening distance approx. 2,3m), measured with MMM at MLP (single speaker + sub):
The response above ~300Hz is almost identical in all cases.
As we can see, the sub-bass below 30Hz is almost 4dB higher with all windows open vs all closed. Above we see that a few peaks (~35Hz, ~55Hz) are 4-5dB higher with the windows closed vs open. Interesting part is also the 200-300Hz area which has the deepest dip with all windows open.
Next let's look at my desktop, nearfield system (listening distance ~70cm), this time a single speaker measured with a single point sweep at MLP (for simplicity; though I verified first that MMM shows a similar response in LF):
Most of the difference is with the lowest modal peak where there is almost 10dB difference in level between fully closed and fully open room! Also we see that there is some 'drift' in center frequency of the peak, which goes up as I open additional windows/doors.
This difference is very audible which is what forced me to go down this rabbit hole in the first place
The result is I created 3 different EQ presets that I have to switch depending on the door/window position!
I'm using the RME Babyface built-in DSP 3-band EQ for room correction in this system, and I modify just the lowest band to correct the moving peak - with this I can get similar response in all cases. Here is an L+R combined response measured with MMM for the 3 situations/EQs:
As you can see, this gets the in-room response to the same ballpark in al three cases.
I guess this all shows that, even with pretty good speakers and access to EQ, there can be some less-than-obvious dependencies to take care of to get consistent sound in a room! Anyway, perhaps some will find this interesting!
First the living room system (listening distance approx. 2,3m), measured with MMM at MLP (single speaker + sub):
The response above ~300Hz is almost identical in all cases.
As we can see, the sub-bass below 30Hz is almost 4dB higher with all windows open vs all closed. Above we see that a few peaks (~35Hz, ~55Hz) are 4-5dB higher with the windows closed vs open. Interesting part is also the 200-300Hz area which has the deepest dip with all windows open.
Next let's look at my desktop, nearfield system (listening distance ~70cm), this time a single speaker measured with a single point sweep at MLP (for simplicity; though I verified first that MMM shows a similar response in LF):
Most of the difference is with the lowest modal peak where there is almost 10dB difference in level between fully closed and fully open room! Also we see that there is some 'drift' in center frequency of the peak, which goes up as I open additional windows/doors.
This difference is very audible which is what forced me to go down this rabbit hole in the first place
The result is I created 3 different EQ presets that I have to switch depending on the door/window position! I'm using the RME Babyface built-in DSP 3-band EQ for room correction in this system, and I modify just the lowest band to correct the moving peak - with this I can get similar response in all cases. Here is an L+R combined response measured with MMM for the 3 situations/EQs:
As you can see, this gets the in-room response to the same ballpark in al three cases.
I guess this all shows that, even with pretty good speakers and access to EQ, there can be some less-than-obvious dependencies to take care of to get consistent sound in a room! Anyway, perhaps some will find this interesting!
