Kubs said:
There is a high pass and low pass setting ..... You are right ... There is some encroachment in the mid section .... Is there anyone in south London / Surrey who can come round and set it up for me
I would run your speakers full range and not use the high pass filter.
Play some test tone frequencies through your speakers with the sub off, starting at say 50hz, then go lower until you reach a frequency where you speakers are rolling off and sound a bit quieter. this could be 40hz or maybe even 30hz if you have room gain.
Now set the low pass to 30hz or 40hz or as close to the frequency where you heard the speakers rolling off and on the 24db setting.
Now get a test cd and play a test tone of your chosen low pass filter frequency through the system(30hz or 40hz?). Make sure the sub is turned up just enough so you can hear it but its not drowning the speakers. Now get somebody to adjust the phase on the sub while you sit in the listening position and listen for when the 30 or 40hz tone sounds loudest. This is the point where the sub is in phase with the speakers.
Now reduce the volume of the sub slowly until you just cant hear it anymore.
Now play test tones starting at 20hz and up and listen to see if you have a flat response. The idea is that your sub will not add to any frequencies already produced by the speakers, just extend the response discreatly down to 20hz or below.