Originally Posted by jaddie
Seems to be a bit of confusion here. There are several functions being blended into one: the LFE LPF, the crossover frequency, and bass management. However, they are actually separate functions.
The LFE channel is an independent channel containing up to 120Hz content, therefore the LPF should be at 120Hz, or LFE content will be missing. Then there's the crossover used in bass management, which would be the more room/speaker dependant function, as it controls how much LF material is crossed over from the mains to the sub. Then there's the small/large speaker size function, which determines if the crossover removes LF material from the mains and redirects it to the sub, or leaves it in the mains AND sub. That function is affected by the crossover frequency setting. The exception is if there's no sub, then the LFE gets distributed to the mains (usually).
Typical bass management crossover setting is 80Hz, but depends on the performance of the room and the mains, and would change the bass character and quality. Changing the LFE LPF usually has very little audible effect as most LFE content is below 80Hz, though technically there can be content up to 120Hz in that channel. It does not change what happens in the mains.
But really, the only correct setting for the LFE LPF is 120Hz.
In real life, there is very little content up to 120Hz in the LFE channel, according to professional film mixers. But yes, there could indeed be.
The issue is whether that content is so important that having it negates any 'issues' which may arise from using a LPF of LFE of 120Hz. I find, for example, that what seems to be in the LFE channel above 80hz is mostly "mush" (I have dual Seaton Submersives so my bass performance is very good and very revealing). By using an LPF of LFE of 80hz I seem to be able to eliminate the mush without having any negative impact on the real bass content.
It seems less than productive, to me, to follow a mantra (the only correct setting is 120Hz
) if actual experience shows that better results are obtained by not following it. This is, of course, assuming one understands all the issues involved in any decision made.
I set my LPF of LFE at 80Hz years ago and have never felt any need to revisit it. Of course, YMMV.