i recently reconsidered my approach to ultimate bass.
i have previously suggested:
http://www.diy-av.net/forum/viewtopic.php?f=8&t=29
but now i realize we can in fact do much, MUCH better.
here is what you do. you take 3 types of 18" woofers each in its own sealed enclosure.
"top" - 96-98 db efficiency 8-12 mm xmax. 800 - 1600W. ex: JBL 2242, BEYMA 18SW1600ND
"middle" - 92-95 db efficiency 15-25 mm xmax. 1000W - 2000W. JBL 2269, TC Sounds Worx
"bottom" - 88-90 db efficiency 30 mm + xmax. 2000W + TC Sounds LMS Ultra
also VERY IMPORTANT from "top" to "bottom" BL^2/Re should increse VERY SIGNIFICANTLY as it does in the driver examples i have given.
now there would not be any crossover ! all 3 would operate in parallel but each one would be EQUALIZED differently. the combined resulting bass subsystem would be used up to about 200 - 300 hz.
the "top" driver would be essentially run unequalized. the chamber volume would be tuned to limit excursion to prevent damage and distortion.
the "middle" driver would be given a bigger enclosure, more power, and its midbass would be attenuated above 100 hz or so. so it would be about -3db @ 100hz and -6db @ 200hz
the "bottom" driver would be given the most power, about same size enclosure as "middle" driver and it would be rolled off starting from 30hz or so. so it would be -3db @ 30hz for example, -6db @60hz, - 10db @ 100hz and -20db @ 200 hz
basically each driver would be allowed to do what it does best but without crossing any one over to any other so that they can all combine and reinforce each other.
both the entire volume of all 3 boxes and the entire surface of all 3 diaphragms will be used for all frequencies ( maximum utilization ) but at the lowest frequencies ( where box volume is the constraint ) there will be bias towards high BL drivers that can compress the box volume better and at higher frequencies ( where moving mass is the constraint ) there will be bias towards lighter coned drivers.
now go build it. you can thank me later.
i have previously suggested:
http://www.diy-av.net/forum/viewtopic.php?f=8&t=29
but now i realize we can in fact do much, MUCH better.
here is what you do. you take 3 types of 18" woofers each in its own sealed enclosure.
"top" - 96-98 db efficiency 8-12 mm xmax. 800 - 1600W. ex: JBL 2242, BEYMA 18SW1600ND
"middle" - 92-95 db efficiency 15-25 mm xmax. 1000W - 2000W. JBL 2269, TC Sounds Worx
"bottom" - 88-90 db efficiency 30 mm + xmax. 2000W + TC Sounds LMS Ultra
also VERY IMPORTANT from "top" to "bottom" BL^2/Re should increse VERY SIGNIFICANTLY as it does in the driver examples i have given.
now there would not be any crossover ! all 3 would operate in parallel but each one would be EQUALIZED differently. the combined resulting bass subsystem would be used up to about 200 - 300 hz.
the "top" driver would be essentially run unequalized. the chamber volume would be tuned to limit excursion to prevent damage and distortion.
the "middle" driver would be given a bigger enclosure, more power, and its midbass would be attenuated above 100 hz or so. so it would be about -3db @ 100hz and -6db @ 200hz
the "bottom" driver would be given the most power, about same size enclosure as "middle" driver and it would be rolled off starting from 30hz or so. so it would be -3db @ 30hz for example, -6db @60hz, - 10db @ 100hz and -20db @ 200 hz
basically each driver would be allowed to do what it does best but without crossing any one over to any other so that they can all combine and reinforce each other.
both the entire volume of all 3 boxes and the entire surface of all 3 diaphragms will be used for all frequencies ( maximum utilization ) but at the lowest frequencies ( where box volume is the constraint ) there will be bias towards high BL drivers that can compress the box volume better and at higher frequencies ( where moving mass is the constraint ) there will be bias towards lighter coned drivers.
now go build it. you can thank me later.