So even though the frequency response graphs produced by the auto EQ look good, something else is amiss that’s not showing on any graphs?
I have heard a few different auto EQ, and I never thought any of them sounded good, but I cannot explain why since the frequency responses look good.
Looking good is a big part of the problem.
As you move away from a source be it live musicians or a speaker, then the proportion of reflected versus direct sound increases in favor of the reflected sound.
Reflected sound however has a lower frequency content than direct sound. So there is a natural HF attenuation. So there should be HF roll off as you move away from the speaker. If you correct for that effect the sound will be harsh and unbalanced.
That might sound superficially good for close multi miked pop music, but for natural instruments, in the concert hall, recital hall, opera house or church it is disastrous.
Incidentally this also drives home the point that listening panels prefer wide dispersion speakers, whose off axis response mirrors the axis response but with some smooth HF roll off, of axis.
Let me just illustrate the point.
Here is the FR of a main speaker at its current location at 2 meters.
The droop above 15 KHz is from omnimic.
Now the "sub/LFE"ouput is blended in at 40 Hz. Note that there is slight roll off and you will see why below.
Here is the FR of the center at 2 meters in its current location. It is rolling off 12 db per octave at its calculated F3 of 48 Hz.
Now lets see the room response.
First row. 12 ft back from center speaker. These results are with the front three and surrounds.
HF decline is starting at 6 KHz. You can not time the speakers for all seats and the impulse response shows that.
Now lets look at the second row, MLP.
Note that the speakers are pretty much perfectly timed for the MLP. HF roll off is now starting at 4.5 KHz. There is slight LF rise starting at 30 Hz.
So that position gives a good rendition of a high priced seat in the concert hall.
Now lets look at the third row.
Like the frontrow, the speakers are not perfectly timed for that position. The HF roll off is steeper. Now there is stating to be significant rise below 50 Hz. This is to be expected given that the rear seats are about 3 ft from the back.
However you can see why I elected to mix the 40 Hz sub/LFE output the way I did. It also shows why you have to be careful not to turn subs up too high.
The room is 29 ft. long, and 16 ft wide with 9 ft ceiling.
So you see you have to be very careful correcting FRs at any seated position.