Originally Posted by m. zillch
Well I go by Audyssey co-founder Tomlinson Holman [among other things he is the brains behind, and the first two initials of THX, by the way] who was one of the main architects behind the entire system we now call "bass mangement" and Chris Kyriakakis, the other co-founder of Audyssey Labs who has written scholarly papers for peer reviewed journals specifically on the topic of subwoofer integration:
One person's opinion doesn't negate the average frequency humans can perceive bass localization (a well known psychoacoustic phenomena). This may vary somewhat by person (our heads aren't all the same exact size, etc.), but the higher you go above 80Hz, the more likely you can localize bass. IMO, 120Hz was a poor choice for the LFE top end for this reason, but I suppose it gives some headroom so it doesn't just fall off a cliff. I'm guessing they were considering many theaters probably had very poor bass in the surround speakers at the time, etc. as well and so pushing as much as they thought they could get away with to the subs (which are typically stereo in a theater) was a good idea. But that doesn't necessarily apply at home. This is why the setting is adjustable. The door swings both ways. You can shift bass to the main speakers or to the subwoofer. There are typically separate settings for the LFE channel, but it works the same way. It will send bass to the main speakers if you lower the number below the maximum. This gives you flexibility for both you and your room.
The idea that "one size fits all" is absolutely erroneous and I don't care what company that guy works for. That doesn't make him god. Too many people are impressed by fame and it doesn't make a human infallible. 120Hz is a full half octave into the potentially localized spectrum. If YOU want bass that can be localized in your subwoofer, go ahead. I sure as hell won't do it. I don't want to be staring at my sub when it should be audibly invisible. Setting that setting to 80Hz does not lose the information. It gets sent to the mains and no sub's crossover rolls off instantly anyway. A 12dB/octave crossover is down only 6dB at 120Hz, but that gives the mains the ability to present it in both channels and remove directionality. I use an even steeper crossover. I cannot tell where my sub is located when it plays.
This filter has nothing to do with speaker roll offs and crossovers.
That is a misleading statement. That only means that the signal meant for the mains (or even a plain stereo signal) is not involved in that setting. The LFE setting is SEPARATE from the crossover for the main channels bass. However, it doesn't negate the fact bass management moves the bass to the other capable speakers when you have no sub or the crossover is set well below the maximum. It still moves the LFE bass to the mains. There is NO REASON to think that is a bad idea unless it causes problems with your room response. IF you have capable mains that can play to 30Hz, you can use a 60Hz point instead for both the mains and the LFE channel if you want. It will play both signals above that point through the mains. You do NOT lose any information. It simply gets shifted to other drivers. Frankly, I find the original "only one correct" bit unbelievably arrogant and absolute horse manure. IF there was only ONE correct point, there would be no adjustability in the setting allowed. It exists because we don't all use the same systems and speakers!
Now if you have two subs and can't localize tones at 120Hz (easy to test with some test tones), then by all means, let your subs play to 120Hz. Hell, you can cross your mains there too then if you really want to. Get a room response with the Audyssey app and see what combinations get you the best possible room response if you so desire. The system is flexible for a reason and one should not fear that, IMO. It's not hard to set it back if you don't like it.