Single 12 box tuning and design help

[Josh Temple]

If anyone can help,

awhile back certain things happened that made me have to sell my setup. Now all i have is and old school MTX MXS1204 single 4 ohm VC. i put it in and noticed that this little monster puts out decent sound but the box its in is extremely too small. and tuned for 45 Hz. My question would be how low can i tune the new box to while still maintaining decent bass at higher frequencies? What types of port designs should i consider? I would like to know the true limits of this sub before i consider trying to get another 15.

Thanks in advance,

Josh

[diatribe]

Here are some options using BassBox Pro. It recommend a sealed enclosure.

Red is 0.75 cu.ft. sealed with a Qtc of 1.04.

Green is 2.0 c.ft. sealed with a Qtc of 0.87., recommended as high fidelity.

Blue is 3.0 cu.ft. tuned to 35Hz.

[Josh Temple]

I appreciate the help. Are those parameters before of after woofer displacement? and the blue is a ported box correct? or are they all sealed?