Very large sized planar driver ( 180square feet) ...possible ?

[newfinish]

adire made a motor ,piston like,capable of moving a 4'x4' plywood like speaker,and they said it could move even bigger sized surface.don't know if they are still available somewhere.

 

[el`Ol]

my guts also tells me ( often correct ) that having a front planar wave pass through the listening spot, clean and loud, can be something desired for HT sub-bass reproduction!!!

I can only tell you again that you won`t get a planar wave when there is a wall opposing the source. Try the simu yourself.

 

[JinMTVT]

I can only tell you again that you won`t get a planar wave when there is a wall opposing the source. Try the simu yourself.

hey! ok
wich simu? the graphical wave simulation?

and how to set it up to it emulates a plane driver?

 

[el`Ol]

Most important is that you not only edit the slit, but also place the linear source (crosses) right into the slit. Then you can draw the walls.

Oliver

 

[JinMTVT]

i do not understand how one can emulate a non point source with point sources ???

even if we move the sources in the slit with the emulator, they still not emit like a plane ??

also, one has to take in account that there will be a room with the same dimension as the base driver itself in my house ..won't be in an infinite situation!

It was brought forward by MJL21193 member to use
some pneumatic rams isntead of magnetic motors..
i don't see any problem with doing that..
do you guys see any ?

are pneumatic ram precise enough ?
if i only require less than 1mm movements, i am not too sure that pneumatic rams would provide the precision
newya i think this idea has to be considered,
as there is no real limit to what i can use as motor

i will try and calculate the weight of the total CF laminated sandwich for this size..with different available carbon prepeg weight and different core thickness
VS flex ..could be interesting
i know we have some sandwiches with balsa cores that we use that are near 1g/square inch!

 

[JinMTVT]

what about using servo motors with linear ball screw things?
plenty available for cheap off ebay or chineese fabs ..

i guess that a few servo motor would be good enough to drive a subwoofer wall ??
fast enough ? precise enough ??

 

[el`Ol]

i do not understand how one can emulate a non point source with point sources ???

In the single slit mode the two crosses in the single slit model are the edges of a linear source.
BTW, did you read all the stuff about wave absorption at the opposing wall in the planar forum?

 

[JinMTVT]

quite a bit ..

are you talking about my other thread ?
or is there more?

 

[JinMTVT]

the only curvature and deflection i can see if from the diffraction ...

even extending walls from the edges of the slit there is some diffraction, but then is going to account for much on a sub bass driver with very high front SD and power?

 

[el`Ol]

Yes, I mean your other thread.
In the simulation the wavefront is perfectly planar when I build the side walls, even better than without walls, but all changes when I draw the opposing wall, and that`s what the active absorption stategies in your other thread deal with.

 

[JinMTVT]

ok nice
that is what i understood also ...

so if we find a way to deal with the rear wall,
the rest could be near perfect ....

though i can see that there is a big difference between
a room with standing waves from rear reflection
and one that has no rear wall and waves only pass by

what do you think about the way we will hear the different wave pattern ??

 

[el`Ol]

I guess with virtually no energy storage in the room you would perceive the bass as very "fast". In a German forum it would give an uprising now, because "fast bass" is a contradiction in itself, I don`t know how it is here, but that`s what I think.

 

[JinMTVT]

i guess that i will have to make a small scale sample to be able to feel it ...

you think a 2X2foot tubbed box would be enough ?

 

[el`Ol]

Better try a powerful sub in your garden.