Originally Posted by sdurani
Sure, but I don't let perfect be the enemy of good.
I'll take perfect, thank you very much!
Ooops, not quite perfect. There's a 2 dB bump at 40 Hz.
That is with a random placement of my 3 subs around a very irregularly shaped room with an alcove to a stairwell on one side, an equipment rack, a hallway to a bathroom in the back left and a back bar in the rear. The width of my room varies from 24' to 16' with about 6 different width dimensions along the course of the right wall. I wouldn't know which one to pick to use as the single width dimension to use for mode calculation.
(BTW, that measurement is also post-Audyssey XT32 but without DEQ and with my subs in Pgm1. It's a single point measurement at the primary LP. It's just the subs, (no speakers), and there is an 80 Hz LPF, (crossover), set. After that measurement, I add a "house curve" by adding Pgm2 and DEQ with an RL offset of 5.)
Originally Posted by sdurani
Those calculators are useful because they can help find subwoofer locations that improve frequency response and seat to seat consistency,
so I don't hold it against them if they can't predict all simultaneous interactions of every single mode.
One row of seating, whether dedicated HT recliners or a living room sofa, is more common than multiple rows; even here amongst home theatre enthusiasts at AVS. Which is why I'll typically suggest placement that addresses width modes, since all listeners will be subject to the same conditions for length and height modes. The latter can be addressed with EQ, as long as the row of seating avoids deep nulls. If Audyssey sees the same problems in every seat...
So irregularly shaped rooms don't make me reflexively dismiss subwoofer placement based on room modes. As long as there are parallel side walls between the sub locations and the seating area, it's worth a try. Where the predictive calculators come in handy is giving me a starting point for possible locations and problem frequencies.
Sanjay, let me ask you something... You keep coming back to this concept of "seat to seat consistency." In general, do you think it's more important to provide seat to seat consistency in the bass than it is to optimize the single "sweet spot" seat? I'll provide my own answer for your consideration:
Looking at the optimal setup for a surround sound system...
...it is obvious that there is exactly ONE seat where everything comes together optimally; the sweet spot. At ANY other location, the distances and levels will be incorrect. For example, if you sit in the right seat, (red circle):
...now you are in the wrong positions for all the speakers. The right speaker is too close; the left speaker too far away. You're off-axis of the CC. The right surround is too close; the left surround too far away. Same thing for the rear surrounds. Imaging will suffer, especially any imaging that depends on "phantom images." You can't make up for that with changes in distance and level setting without totally screwing up the primary LP.
You're also at the wrong angles to, and off-axis of all the speakers at all locations other than the sweet spot. This will mean the timbre-match that you've worked so hard to maintain will be lost outside the sweet spot. Of course, you can use "Constant Directivity" speakers and get close to the same timbre at seats outside the sweet spot, (and if you can, you should), but realistically, how many users do that?
Seats other than the sweet spot are, by definition, compromised, even outside the bass range for the reasons I showed above... and there is no way to fix those compromises without screwing up the sweet spot. And you definitely can't fix more than one other seat. If you "fix" the right seat, you'll not only screw up the sweet spot, you'll really screw up the left seat. The same holds true for the bass. If you try to optimize the bass for an "area", you must make compromises at the sweet spot. They may not be big compromises, but the adjustments you would use to correct the response over an area would have to be different than the adjustments you would use to correct one single spot. If they're different, they can't both be optimal.
To me, it makes little sense to me to provide "better" bass at more listening positions, (LP's that are already compromised in so many other ares), if it compromises the bass at the only spot in the room where EVERYTHING else is optimized. If that means I end up with an "Archie Bunker" seat, I'm OK with that. If you ever visit my theater, I'll get up and let you sit there.
In fact, I'll insist on it.