Originally Posted by djbluemax1
Well, here's my personal take on raising my crossovers from their default 40Hz to 80Hz all the way round and how it affected things.
First off, a description of my system to establish a baseline.
Multi-disc player: Oppo BDP-93
AVR: Onkyo TX-NR5008
Additional amplifiers: Emotiva XPA-1 500 watt monoblocks for the L/C/R
Speakers: Boston Acoustics E100's for the LCR. My rear surrounds are older 3-ways that have built-in 12" woofers.
Subwoofer: Seaton Submersive HP with built-in 2400 watt amp.
I watched the pod race scene off the Blu Ray of Star Wars Ep 1 probably about 15-16 times going back and forth between 80Hz and 40Hz.
I first watched the entire scene with my regular 40Hz crossovers, then watched the entire scene again after changing all the crossovers to 80Hz, then went back and watched those scenes/chapters again with the crossovers reverted back to 40Hz, and yet again with them set to 80Hz.
I then used the A-B function of the Oppo to continuously loop specific scenes from those chapters while switching between the 40Hz and 80Hz settings.
My take on it after all that?
1) In my system, there is no lack of 'slam' in either setting. The overall SPL's and impact in the lower octaves is similar
2) There IS a discernible difference between the two settings in my system. As it turns out, after doing this test, it appears I can localize bass noises below 80Hz to some extent.
In some of the scenes that I replayed/looped back to back, over and over again, I could actually hear the difference between the crossovers in what sounds came from the satellites vs which were handed over to the sub, i.e. in some of the scenes where the other pods fly by, with the 80Hz setting, I could hear that the upper frequencies panned with the speakers, but the low end 'rumble' didn't pan, whereas with the 40Hz crossovers, the entire sound effect of the pod flying by panned across the speakers.
There was a point where I could no longer localize panning though. Basically the really low end of the rumble was non-localizable, but that range appears to be below the 40Hz crossover setting, as once again, I could hear some of the low end rumbles of the pods flying by NOT panning when set to 80Hz, where I would hear it all pan when set to 40Hz, but the lowest/deepest rumbles sounded... formless/sourceless and non-localizable regardless of crossover setting.
For me, this made the 40Hz setting more involving in those scenes, because it produced a much more realistic effect of a large object producing high SPL low frequency noise passing by, as opposed to the 80Hz setting that had the higher frequencies pan, but all the sound from 80Hz down not move around the room.
Had I not specifically tried this and demo'ed them back to back, I would not have realized that I could hear/sense this difference. It's a bit of a downer to me personally, because I was planning to timbre match the rear surrounds using smaller versions of the E100's that have the same tweeter, but those speakers (E70's) have a -3db point of about 63Hz anechoic. Now I have to think deep and hard about this, and it's going to be a pain should I ever decide to change my surround setup, knowing that I'll now have to look into surrounds that can run flat down to the 30's, where it would be so much cheaper and easier to look at all the options that only need to go flat to THX 80Hz specs.
As I mentioned earlier in the discussion, I've also determined that there is a percussive/concussive factor to low frequency capable surrounds. In that example I'd mentioned, it's easy to roughly indicate the direction of the explosion of a bigger firecracker from the direction of the pressure/shock wave. I find this evident in movies with surround gunfire too, and once again, the 80Hz crossover tends to neuter that.
As far as music goes, the effect is much more subtle in my setup, but it's there on tracks where there's material in that region between the 40 and 80Hz crossover settings.
Chesky records is known for their use of stereo mic'ing, in particular, their use of single point mic'ing with a Blumlein pair configuration. This mic'ing technique tends to produce recordings that not only capture the artists, but the space they were recorded in as well.
On David Chesky's Area 31 album, tracks 3 and 4 particularly (Concerto for Violin and Orchestra, Tom Chiu, violin: Allegro Maestoso and Wonjung Kim: The Girl From Guatemala respectively) both exhibited these differences with the 2 crossover settings, because both these tracks have instruments digging into that 40Hz-80Hz range (and on rare occasion, a little lower even).
One of the things about Blumlein mic'ing is that properly done, they not only convey a sense of the space the recording was made in, but they produce recordings with soundstages that appear to have greater depth. The 80Hz setting on those tracks produced a flatter fuzzier depth image of the bass in those 2 tracks than the 40Hz setting, but as I mentioned, the difference was more subtle to me than the more blatant, "these frequencies are panning and THESE frequencies are no longer panning" differences in the Star Wars sequences.
As always, YMMV, but it looks like I'm going to be sticking to the 40Hz crossover settings on my own system.
As far as the point of this discussion taking place in the Audyssey thread, as has already been mentioned numerous times, I'd say it definitely has merit and is on-topic as the previous common advice was simply, "run Audyssey, raise all crossovers to 80Hz if they are set lower. Do not lower any crossovers". Well, in my own setup, it seems that there are benefits to using lower crossovers if the system is capable of reproducing them flat at the volumes that will be used.