Sub Woofer Madness

Hello everyone, i picked up a pair of 18 inch drivers that i would like to use in a sub woofer design.  They were made for B-52 and the only number i have is SP-1804.  They are high output professional drivers rated at 550 watts.  The optimum box size provided by bass box 6 pro high fidelity says the optimum box size is 2.39 cu. ft. and it's f 3 would be 105 hz.  I would like to build a larger box in order to lower the frequency.  First i will never run more than a hundred watts through them, will i have to worry about damage because of less damping keeping the cone where it should be and second will the sound quality suffer from a larger box?  Thank you for any input.

These are the specs from that driver: www.parts-express.com/b-52-sp-1804-18-ca...ofer-4-ohm--299-2301

Based on the T/S-parameters I would first look at a band pass cabinet, or something semi-horn loaded (like a Cubo 18 or Cubo Sub). That being said, with just a few hundred Watts, something between 4 - 8 cu. ft. tuned to roughly the Fs (27 Hz) should do. Because of the low Qes, the response is going to simulated quite peaky but as long as you keep the peak under 5 dB and preferably wide, it's fine (all things considered).

Cubo