dipole midbass section


Disabled Account
2007-12-31 1:16 am
i've been wondering what kind of application i can come up with for this woofer:

21" Beyma

and i figured it out - dipole !

but not a subwoofer, just woofer ... it would probably be able to handle stuff down to about 60hz and below that frequency a subwoofer would take over.

basically i think this driver would be excellent to cover the region where all the mud from room modes is - 60 to 200 hz or so.

i also thought of a way to pack four of these drivers into a reasonable sized dipole "box" ... it would be like a pyramid inside of a box missing front and back. two drivers would face forward and two back to cancel motor distortions. i could maybe draw a sketch sometime if necessary.

above 200hz there arent any serious anomalies with room response and below 60hz you will not find most of the musical instruments like voice, etc so some accuracy can be sacrificed there

what do you think ?


Disabled Account
2007-12-31 1:16 am
Magnetar said:

I think the bass drivers will modulate the cone of the 12 and muck up your good sound

hm... thats a valid concern

lets then swap the 12" for this 10"

10" Beyma mid

and make the rear volume behind it very small making use of the fact that it has high Fs and low Qts to bring up its resonance frequency to about 200hz ... then the compliance of air behind it should effectively prevent it from moving when the woofers try to modulate it

as a matter of fact we can put four of those 10s in there to make up for lost displacement ... they cabinetry would get a little more complicated but i can still see it ... again i can make a sketch if necessary

then this whole thing could be used up to about 500 hz and on top of it all we could mount another concave pyramid shaped concentric array out of lets say four 5" midranges and a 3" compression driver in the middle

it could all sum very nicely out in space. the two horns would have similar directivity and the crossover between the two horns (each of them a concentric array) would be low enough (500hz) to avoid lobing even with large C2C distance.

and then the well controlled directivity would extend down naturally below the range of the horn courtesy of the dipole ...

then just between the two horns a bullet supertweeter could be placed directly on the listening axis to fill 10khz - 50khz range

all in all it would be a 2+2 way + subwoofer + supertweeter ...

anybody wants to build this ? :)