So I have the following equipment I'm working with and want to build a new HT sub.

Right now I have a Mach 5 MJ18 on a Parts Express 500 watt plate amp. I think it's around 6 cubes tuned to mid to upper 20's, not sure anymore.

The box design isn't working with my new arrangement so I want to build something new.

Basically I'm looking for opinions on if I should use the MJ18 again or use the pair of Sundown sd1 12's that I have.

What would you do in my situation?

I need somewhat of a multi purpose setup. It would be used for music, movies and video games but mostly leaning towards music.

my buddy has one of those 18s in a HT setup.

I dont know the exact specs but i believe it's around 12cubes tuned in the 20s.

He mostly watches movies but i've heard it play music and wow... it fills the whole basement up.

He also runs it off a 1400w Behringer amp.

1 18 has more cone area than 2 12s also. IT's your best bet to rebuild the box.

If you mostly listen to music on it, you need to tune it higher also!

Your current box would help tremendously if it were tuned in the lower 30s. Making it bigger... i'm not for sure how much you would gain.. if it was audible or not.

For a quick test, can you chop off some of your port now?

Tell me your box dimensions, port area and port depth so i can tell u how much to cut off and see if u like it a lot better before u destroy the box.

Slow down. Not so sure any of that advice makes sense.

First step, what about the box isn't working with your current arrangement?

What are you using for speakers/power for your mains?

HT sub and music sub are different. You imply you want it for music, but that will require a SSF otherwise you could have some issues. We can help if you fill us in.

I don't really have much of a problem with the current sound, a little more accuracy would be nice, but where it's at does pretty good for movies.

The problem is the box right now just isn't a good fit size wise with my new furniture layout, being that it's still bare MDF because I never decided want I wanted to do it's a good time to build something else.

The current box is a rectangle, if I rebuilt it'd probably be closer to a cube.

I know sealed wouldn't have as much output, but I'm not a REALLY demanding listener that cranks it up all of the time.

My mains are Zaph BAMTM towers running off an 85 watt per channel Denon receiver, no center or surrounds at the moment.

If you like what you have why wouldn't you just rebuild it with the same internal volumes to fit your space?

Eh, I'm a tinkerer, I got the stuff and I wanna play with it.

Of course to tinker you should be able to describe what you'd like it to do better and then we can give you direction

If it's mostly for music, I would use the MJ18 and build a box that's about 6 cubes tuned to the upper 20s. Wait, you already have that.

But since you're a tinkerer, may as well try sealed.