Setting Sub Crossover Freq


I have speakers that have rated sensitivity of 89-90dB
and a frequency range of 45-22000/50000Hz.

Anyone have any suggestions where to set a sub crossover frequency given these specs ?
mjmch2003
I have set it to about 50-55 on the low end, althoug it's tought to tell with the rotary dial and now the volume is at about 2 o'clock. Seems to been pretty decent. i get some nice low end extention, where the speaks drop off.

Worth nothing, the speakers are ACOUSTIC SUSPENSION (no ports)
My brother (not on a'gon) opined:

"Who knew the level of dorkdom in the world? U do need to turn the power up with lower frequency settings. Reason being, wider, slower waves need more watts to reach the same amplitude of percieved loudness. 80 hz is a little muddy to my ears for a sub. I'd try around 65 hz. Keep in mind that the frequencies are actually notes, so you may want to tweak it based on what key the music you are listening to is in. To figure out notes, keep in mind 110 is an "a" and use pythagorean fractions to tune down to the key you are in. 55 is also "a" ...."
Mjmch,

If you take only ONE THING from this thread, make sure it's point #2 from Drew.

Marty
I should clarify a bit. IMHO, the greatest benefit you'll get from a(n) (optimally installed) sub occurs ABOVE 70hz. This benefit is the ability to address the quarter wave null and the "hump" that so often occurs about half an octave to a full octave above that.

That's why I highlighted Drew's observation. His crossover scheme in point #2 may work well for the 1/4 wave null, but there is another approach to the issue, too. You may find it easier to sharply low cut your main speakers and cross to your sub above the 1/4 wave frequency. You can then address the problem effectively by optimizing the sub's placement in the room.

Stereo subs crossed even higher (app. 120hz to 140 hz) will allow you to address the "thickness" that often occurs in this range. BTW, "bassbusters" or other hemholtz devices can also be used to deal with this issue. If you don't want to go that route, IME, you can usually place stereo subs such that imaging is unaffected despite the high x-over point and frequency response will much, much smoother through the most troublesome ranges.

Good Luck

Marty
I second the use of REQ Wizard. My Maggies are rated to about 45HZ, but the in room response according to the room EQ wizard is 65hz. I was running my sub crossed over at 45 and I felt like I had a gap in the low end, this is was prior to running the REQ Wizard and want prompted me to run in in the first place. I bumped my crossover up to 65HZ and all is good now. The optimal setting would be 80hz but the sub was a bit too localized at that setting, this may or may not be an issue with your set up, it just depends on the placement of the sub in your room.