just wanted to know what are some things to look for in a great sub. i know xmax but some other things that are important. just little question like why different size surrounds?

Totally depends on the intended use.

Xmax as a singular spec really isn't all that important. You have to put it in context, depending on the situation it might not matter much...

okay im talking what are some things to look for in a soild sub it dont matter a badass sub. ok what to look for in both daily driver and spl subs

I can't really speak for SPL subs, as I'm not an SPL competitor, but...

You need to pick a driver that's going to work well with the type of enclosure you're going to be using. If you only have room for a small sealed box, going with a speaker that has a large Vas and an EBP (Fs/Qes) over 100 probably isn't your best choice. If you want a driver that can deal with transients very well, avoid high inductance designs. Lots of linear travel is required in something like an infinite baffle or sealed enclosure, but in a horn or transmission line Xmax doesn't matter anywhere near as much.

Basically, it's all one huge compromise. You just have to pick what it is you can give up, in exchange for something else...

I can't really speak for SPL subs, as I'm not an SPL competitor, but...

You need to pick a driver that's going to work well with the type of enclosure you're going to be using. If you only have room for a small sealed box, going with a speaker that has a large Vas and an EBP (Fs/Qes) over 100 probably isn't your best choice. If you want a driver that can deal with transients very well, avoid high inductance designs. Lots of linear travel is required in something like an infinite baffle or sealed enclosure, but in a horn or transmission line Xmax doesn't matter anywhere near as much.

Basically, it's all one huge compromise. You just have to pick what it is you can give up, in exchange for something else...

thanks man thanks

Well said Jim.