Its Fs is 20Hz! And its super loud at 20hz with no subsonic filter! You're wrong its tuned fine at 20hz trust me come have a listen! I put it in a 4ft3 box sealed and produces much deeper and louder sound with my ported box. Don't be jealous that you cant find my subwoofer anywhere anymore. Best subwoofer in the world tuned @ 20hz with 2500 Crown amp watts powering it!
Yes, but F3 pretty much always ends up a little bit above Fs.
No matter how you calculate the T/S parameters of your sub driver, the absolute lowest F3 is 27 Hz. The reason being is that the driver has above average sensitivity for a sub driver. There is an inverse relationship between flux density and bass extension. So they made a reasonable trade off between bass extension and spl. There is nothing wrong with an F3 of 27 Hz, with room gain there will almost always be some added extension.
Second order means a roll off of 12 db per octave.
I certainly do not covet your sub driver.
This is the FR of my integated left and right full range triamped speakers.
Now the Fs of the four bass drivers is 20 Hz. Again the calculated Fs of the aperiodically damped TL bass lines is 27 Hz. But you can see that in room measurement shows good extension to 20 Hz from room gain.
However these are true reverse tapered aperiodically damped transmission lines that roll off second order 12 db per octave below F3, rather then fourth order, 24 db per octave of a reflex ported enclosure like your sub.
The measurements were taken from this speaker. No sub is required.
