[MaxCast]

Wondering where the majority xo to their sub in their home theaters...if you have the option.  More and more processors/receivers are offering optional cross over points.  This is for front speakers to sub.  If you can xo the surrounds different from the mains....do you?

[StevenACNJ]

I have a Lexicon MC-12 which allows the user to set various sub crossover points:

1. Main L&R - 60hz
2. Center - 70hz
3. Surround L&R - 80hz

[James Romeyn]

I use the pre-pro xo point to flatten a huge +13 dB bass mode at 80 Hz.  The fronts are crossed at 110 Hz.  The sub output of the pre-pro is also low-pass crossed at the same pole.  Then the sub's internal low-pass pole is set below the 80 Hz mode, at about 65 Hz.  Wahlah!   No more bass mode, gone.  Must fine tune by ear the sub's phase, xo pole, & level.  It works.  I got flat bass in a room that is otherwise virtually intolerable.  A Helmholtz radiator could also eat a bass mode, but I've yet to experiment with one.

I believe the above function of a pre-pro is a distinct advantage compared to not using a pre-pro, even playing CD's in stereo.  For this reason, I believe every room has a unique xo point that works best, compared to every other room.

[Bill Baker]

This would depend on the speakers being used. I prefer a x-over point to be a low as possible. Even in HT systems, I like to be below 60Hz if possible. For 2-channel, not a big subwoofer fan.

[James Romeyn]

If you got a room with a 13-15 dB mode at 80 Hz, you got a sum total of 3 choices, & no more:

1. Electronically skirt the mode as described above or with some other eq method.
2. Utilize a Helmholtz resonator to eat the mode.
3. Get a new hobby.

There is no such thing as high-end audio with the above mode in the circuit, IMO.  

If there's another choice, I'm anxious to learn of it.

[Dan Driscoll]

Wondering where the majority xo to their sub in their home theaters...if you have the option.  More and more processors/receivers are offering optional cross over points.  This is for front speakers to sub.  If you can xo the surrounds different from the mains....do you?

I don't have a sub, but if I did and had the capability,  I would cross my main speakers at 40 or 60 hertz, the center and surrounds at 80 hertz.

[ctviggen]

You could move the speakers/subs to reduce interaction with that mode.  You can't change physics in terms of the modes that a room has, but you can change how your speakers/subs interact with those modes.  Nonetheless, 13db is high and this method won't get that much of a decrease.

[ctviggen]

For instance, 80hz equates to 14.21 feet wavelength.  Assuming the peak is all axial mode, a null should occur at 14.21/4 or about 3.6 feet.  (See the picture here http://www.mcsquared.com/modecalc.htm, where the room mode null occurs at lamba/4.)  If you place your subwoofer that far into the room, you'll minimize interaction with that mode. By contrast, if you place your sub near the wall (creating the axial mode) (or any multiple of 7.1 feet from the wall), you'll maximize interaction with that mode.

[byteme]

I use an SVS sub only for HT purposes crossed over at 60.  Bass EQ'd by a Behringer Feedback Destroyer which keeps respons darn flat all the way down to 20hz where things roll off a bit.  I've got a bit of a dip (approx 1db) at 56hz for some reason...but it's much better than it was!

Now that I've got the HT couch with buttkickers in it, I don't have to boost the SVS quite as much as I did and my .1 channel runs probably only 2-3db "hot" over the rest of the 7 speakers which are all bang on calibration wise.

[ScottMayo]

Wondering where the majority xo to their sub in their home theaters...if you have the option.  More and more processors/receivers are offering optional cross over points.  This is for front speakers to sub.  If you can xo the surrounds different from the mains....do you?

I cross at 40Hz, but I've been known to kick it higher for movies.