This is not as easy as you think.
Throw that speaker away! The relationships of a driver and it's enclosure are complex, and you're better off buying a sub in an enclosure where the engineering has been done for you.
First of all, speakers, especially at low frequencies, have to be in a box otherwise the sound pressure they make on a forward excursion rushes around to fill the vacuum created in back, and no sound is radiated. A driver in free air will produce no bass.
Putting them into a box keeps the backwave energy from causing cancellation, but also "stiffens" the movement of the cone since movement in now produces pressure and out produces suction--that limits the long excursions needed for deep bass. A woofer in a small box can go very deep, but only if its cone is small enough that excursion is not limited by the suction/pressure effect. For loud bass, you need a bigger woofer, and a bigger box is a must or the deep bass will be missing. To my ears, the deepest bass is the nicest part.
Some manufacturers use "servo feedback" that monitors the cone position and causes the amplifier to correct movement errors caused by enclosure characteristics. Velodyne (high end) and Yamaha (low end) and others make these. For quality rather than quantity, its the best way to go. It's clear your level of expertise is going to require a freak accident for you to get optimum results with that undefined speaker that you have.
Servo control also ensures that your sub will be well damped--that is, that quick bass sounds (transients) will end quickly like they are supposed to. Poor damping will result in muddy, ringy bass that will destroy the clarity of the sound.
Also, about placement. Rooms resonate at the frequencies of their dimensions. A cubic room is the worst possible case since L W H will all have the same resonance frequency. Hopefully you have an irregular room with angled surfaces. Resonances can be reduced by not placing the sub near intersection surfaces--never in a corner. When you have resonances, you will also have uneven bass--you'll hear it in one place and not the next, because the reflections will be additive at one point and cancelling each other at the next. Much experimentation is required, but stay away from corners and avoid any intersections if you can.
