Speaker relative efficiency/sensitivity when using a high pass filter


Is there a formula/algorithm/rule of thumb for calculating how a speaker's power requirements might change when the lower frequencies are handled by a subwoofer?  Specifically for a ported speaker with a supposed frequency response down to 35Hz and an a 89dB sensitivity with a second order crossover at 80Hz. I know it goes down but by how much? I recognize that power requirements increase as frequency decreases but is the difference enough to allow for a less powerful amp? I would think so.

 

tcutter

@nymarty I am using a Devialet 400.  It has high and low pass filters along with time delay. I have a Dayton Audio SA1000 as my subwoofer amp with second order and fourth order high and low pass filters, respectively, at 80Hz but I am not currently using these. I would if I were to go with separates or an integrated with a tape monitor.  I'd lose the time delay feature of the Devialet but would hopefully make up for it with other attributes.  I could also use a miniDSP or equivalent which you might consider as well.

@lonemountain Do the small speakers you measured have considerable bass output? I would guess that a speaker that goes to 50Hz would yield less of a gain than one that goes to 35Hz. 

Similar but different question: with crossover (12 db/octave) at 200 Hz, how much (percentage) of the power goes to the low pass, how much to the high pass? 

Background: trying to determine (for class A or tube) what power rating for the amp I should eyeball for the high pass.