Hi all, Since a good month, I played with different low pass / high pass crossover settings and I find something isnt right. I have a DIY Tempest subwoofer and my mains are Paradigm Monitor 9 v.3. These floorstanders are powered by an Anthem MCA-20 stereo power amp and the av/receiver is a Yamaha RXV-630. So to only use the Paradigm crossover unit, I set my towers to large (useless anyway because I use the main-out of my av/receiver), I use "MAIN" for the bass (I can choose between SWF, MAIN, BOTH. The Tempest plate amp crossover is logically set at its maximum, at 150 Hz, in order to not have a the entire signal from the X-30. Normaly, I use 50 Hz for the low AND high pass because the Paradigm have plenty of mid-bass kick and I let the Tempest to do the rest. So now, I begin to explain whats happening... One day, I suddenly wanted to have the mid-bass kick from the Tempest so the towers would have to work less. I changed first the high pass setting to 80 Hz, by placing the connections behind the crossover unit at the right place and I changed the low pass to 80 Hz too, by turning the low pass knob. Then, I played different songs, songs which are very dynamic... !!! !!! To my big surprise, I heard LITTLE changes from the bass produced by the Tempest. In fact, I didnt find to have more mid-bass kick from it. In the other way, the changes in bass/sound from the towers was obvious and I could even see that the woofer excursion was reduced during kick drum passages. Not so long after, I changed the low pass seting from 80 to 35 Hz (lowest setting). Woaa... very little changes again. Its like at either 35 or 80 Hz, some frequencies arent well filtered at all. So here are some numbers I would like to share with you. I measured the outpout very near the woofer, something like 6" because I didnt want the room to have an effect on the results. If you dont already know, the low and high pass of the Paradigm X-Over unit reduce the outpout by 18 dB/octave. I played a tone of 50 Hz for the test. Crossover setting==========Measured output -----35 Hz----------------------99 dB -----80 Hz---------------------101 dB -----120 Hz--------------------104 dB -----150 Hz--------------------107 dB I dont know if its me, but I find the results weird for a 50 Hz note!