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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
phusis's avatar
phusis
1,209 posts
 

@erik_squires 

How did I refute myself?

erik_squires
16,121 posts
 

100 Watts is not enough, but it is enough.. ... but you can't tell by wattage... Funny.

phusis's avatar
phusis
1,209 posts
 

@erik_squires --

"100 Watts is not enough, but it is enough.. ... but you can't tell by wattage... Funny."

And we also read and make of it what we want to, right? :) As I'm sure you can assess from my original reply I'm not, depending on the context, in complete disagreement with you, but that's not to say I refute myself. I merely try and point to scenarios where 100W can be more effectively utilized (if still not being "overkill" per se), but those are scenarios outside of your context, and so my main contention still holds. 

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lonemountain
455 posts
 

In pro this comes up in "bass managed" speaker placement in ATMOS systems.  When you roll out the bass of a small speaker, how much does the total SPL capability change?  The answer is you have to measure it.  We did so at the ATC factory and it only gains around 1dB total output SPL to use a HP filter (bass management).  There exists out there some manufacturers that state massive improvements in SPL when bass managed, I'm not sure how they arrived at these new measurements and conclusions.   So I think from a practical standpoint, you'll get a little improvement in total SPL by filtering out LF, but its less than you'd guess. 

tcutter OP
107 posts
 

@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. 

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