[milosz]

I have two frames with 2 OB 12" subs each with the Rythmik servo amps based on the Hypex 400 crossed over at 45 Hz with a DEQX along with my tri-amped MG 3.6's (DEQX again, I have two of them...)

The sound is spectacular.  The OB subs blend seamlessly with the bass panels of the MG 3.6's and I have decent response down to 16 Hz.  And crossing the subs over at 45 Hz saves my MG 3.6 bass panels from low bass punishment, meaning I can play them louder without slapping the diaphragms against the magnets.

The OB subs are fantastic!

[Early B.]

If possible, move those subs further into the room (beyond the AV cabinet) and they'll sound even better. You may realize that you don't need the DEQX. Also experiment with the subs playing much higher than 45Hz so you can take full advantage of them. One more thing -- those are some slick sub amp boxes.

[corndog71]

Yeah, open baffle subs should be minimum 3’ from the front wall.  You are definitely not getting the best performance out of them in that set up.  You could even put them against the side walls outside of the Maggies.

[milosz]

Thanks for the suggestion. I tried them out further into the room, the sound wan little changed, measurement  showed about the same - 3dB point of 16 Hz. It's possible I could have gotten more SPL out of them further in the room, but in their current position I can easily get my 95 dB overall system SPL goal.

In addition to affording a much steeper crossover slope, the DEQX corrects for things like group delay and so on, I've tried without it and the sound was not nearly as good.

[Early B.]

If you're using the subs mainly for home theater, then placing them close to the wall is fine.