[Scott Dorsey]

In article , Trevor wrote:
On 28/07/2017 5:17 AM, Scott Dorsey wrote:
You get low frequencies by moving the driver resonance down and moving the
box resonance down. An unfortunate side effect of this is that you now
have to move more air, which means either having to increase the driver
surface area or throw (xmax). There's a reason you don't get 20 Hz or
really even 60 Hz out of a box and driver this size.

Not necessarily. It is quite easy to get 20Hz from a 4" driver, but
sadly the maximum SPL will be so low as to be totally inaudible!

Right... because you cannot move more air, as I said.

That's the bit most companies making small "sub woofers" would like you
to forget. :-)

Some folks have had success with driver designs having crazy high xmax.
Carver managed something that worked better than you'd expect. Mind you
this also limits you in your porting design.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."