Originally Posted by Bill Fitzmaurice
Almost all subwoofer amps are bandwidth limited to low frequencies, otherwise they'd be much more expensive to make, so LFE inputs are still effectively low passed. As for a sub's internal low pass filtering 'interfering' with that in the AVR or an external DSP, they don't. For that matter the two can be cascaded to realize a higher filter slope, for better rejection of above bandwidth content.
My SVS sub is not bandwidth limited. They assumed I would provide my own crossover, and that makes the amp even cheaper to make. The LFE version of the Rythmik subs goes out to 200Hz, so I would like to make mine similar as well. It's not like I want the sub to blast a 90dB sine wave at 200Hz or anything.
Right now, I am somewhat concerned that because of this extra filtering, the two halves of my crossover aren't quite matching up. My non-LP-filtering SVS sub, which is right next to this Rythmik sub, lets a tiny bit of higher freq noise leak thru (I can hear it if I put my ear close to the sub), and I think it integrates a little bit better with my speakers. (This is just an opinion without having done further tweaking, and is not a statement of fact)
In any case, if I wanted steeper filtering, I could do it thru my own crossover, thanks.