on the hpf i have it set to 20hz with but48 and but18 on the lpf 80hz now what should i do there?
Actually, set the high pass filter to 20hz, 2nd order butterworth. This will allow for more extension, and still protect the driver from unloading under tuning.
You need to use an external amp to your main speakers so you can control both the subwoofers and mains with the DCX to get your optimal integration. The built in crossover system in the receiver is primitive and inflexible. If you are using stereo/dual subs, and placing each one within 3 or 4 feet of each main, I would cross at 80-85Hz, 4th order. Fine tune the adjustments for main and sub until you get the smoothest measured response.
I must say so far without any equalization yet this is the best sounding sub i have heard!
Just wait until you find optimal room position and apply some correction EQ.
BTW, you can make the sub sound like any level of 'tightness' that you so desire using the DCX. After you have set it up and applied your correction EQ, etc.; activate a low shelving filter of 6db/octave rate. Center it's frequency at about 35hz as a starting point. Now set the filter for -2 to -4 dB. This will apply a subtle low end taper, and now it will sound essentially like a highly dampened sealed box. Some people prefer this type of sound. Well, you can have that sound if so desired, and yet still have the massive output levels and low distortion available from this ported system.
-Chris