Alan's input is quite valuable in explaining the subtle point of slope in the low pass filter at the amp/receiver. If I understand correctly, when the cross over is set to 80Hz and the slope is 24dB/octave then the M80s will produce 40Hz but at a level that is 24dB less and 20Hz at a level that is 48dB less. Higher the listening level, the more prounced the work by M80 at this low frequency. If the slope is less steep (12dB/octave or 6dB/octave) or if the cross-over is set lower, bass duty for the M80 would be proportionally higher. This is the basis for setting physically large speakers like the M80 to "small" in order to unburden them of low frequency work at high listening levels. While there is no "brick-wall" on the receiver side regarding the low-pass cross-over, Alan's recent article on subwoofer calibration indicates that the cross-over point in DSP-driven EP subwoofers actually resemble a brick-wall (i.e, no slope). He recommends setting the cross-over at the EP subs to same cross-over as in the receiver. I think many of us would like some more explanation on this before cascading the cross-overs.
John
