Designing my first Home Theater Sub

[Evazan]

I am currently designing my first box for home theater. The sub I am using is an RE SE 15 and the T/S parameters are:

Electrical Q Value -Qes: .55
Mechanical Q Value -Qms: 4.3
Total Speaker Q Value -Qts: .49
Free Air Resonance -Fs: 22 Hz
Equivalent Compliance -Vas: 209 liters
One-Way, Linear Excursion -Xmax: 18 mm
Efficiency - SPL 1W/1m: 88 dB SPL
Effective Piston Area -Sd: 810 cm^2
DC Resistance -Re: 2.8 ohm
Nominal Impedance -Znom: Dual 4 ohm
Thermal Power Handling -Pe: 600 W
Force Factor -Bl: 17.7

I am using WinISD Pro and have read everything about designing a box with it but one thing I still don't really know is what a good curve should look like. Most tutorials say to play around till you get something you like but I don't know what I am looking for. Here is what I have come up with.



This is a 6 cubic foot box tuned to 21 hz. I think it looks ok but honestly don't really know enough to say. Another problem I am dealing with is cone excursion. According to the graph if I give this sub its rated power of 600 watts it will exceed xmax from 25-45 hz which can't be a good thing.

I also looked into a sealed box which I was using in the car but the plot of that box seemed really bad. In a 3 cubic foot box I get an f3 of 35hz and it says I am exceeding xmax for 45 hz and lower.

I think I may be misunderstanding something when it comes to xmax because I ran this sub in a sealed box in my car with 600 watts of power and it didn't bottom out with a 20 hz signal.

I also read about sealed boxes with Linkwitz Transform. When I add the Linkwitz transform to the sealed box it gives a very nice and flat curve with an f3 of 20hz. It almost seems too good of a curve to be true. The only thing is I don't know if my knowledge of electronics is good enough right now to attempt building one and I don't want to spend a lot of money on one.

I should probably add that I am not looking for a huge amount of SPL out of this box. My mains are not big and the only reason I am using the 15 inch sub is because I have it laying around the house not doing anything. My main goal is just to reproduce very low frequencies for movies and to integrate fairly well with the mains.

Sorry that this post is all over the place but I am finding that designing a box for a subwoofer isn't going to be as easy of a task as I first imagined.

I am attaching the WinISD file for this driver to make it easier for anyone who wants to help me with this project.