Box Frequency , Subsonic Filter , and Low Pass Filter

[Alien Mantis]

Good information.

I have been studying graphs like these. If you understand specs and graphs, you can predict how a certain setup will perform.

I was looking at Xmax when choosing a sub. That is one reason I went with the Type R. It has an 18mm Xmax, which is pretty good for a sub that costs around $100, and can handle 500watts RMS +.

I understand that cone diameter + Xmax = SPL.
The more air you can move, the louder the sound.
The faster you can move it, the more controlled it will be.
A 12" sub that has an Xmax of 10mm, is roughly equal to a 10" sub with 16mm Xmax.
Then you factor in the box type and volume, and the power you are putting to it, and you have your setup.

I understand what you mean about the SS filter. If your setup has a SS filter, you can cut all the freq's below that setting, and you don't run the risk of over-excursion on your cone due to it trying to play those super low freq's, even though they drop off sharply anyway on their own.
( This is what "roll-off" refers to. Or sometimes they call it "drop-off". )

Sealed boxes control roll-off much better than ported boxes.
It's always best to just cut those freq's, then the signal never even gets to the subwoofer, but my amp does not have an SS filter on it.
I wish it did, but if you don't try to overdrive your sub, roll-off should keep you safe.
The other benefit of the SS filter is: since the amp isn't even trying to push those freq's, more of the amps power can go towards driving the signals it is supposed to be pushing.

I totally love SS filters.
But my amp doesn't have one.
I also love subs with long linear excursion numbers, because I know I can drive them harder and they will take it and ask for seconds.
A sub with a small Xmax number is easy to bottom out.
They are tight, fast, and responsive, but they don't move as much air, and can bottom out easier.
Less air = less SPL.

It's always a trade-off.

The setup I am running now seems to be good. It's a nice compromise between SPL and SQ. I was thinking about trying the sealed box, but I think I will just stick with this setup. The more I listen to it, the more I like it. So it's all good.