Hello People, well seeing as you're the experts. I want to embark on the wonderful world of DIY subs, and have come across these two drives (specs below) and don't understand why the supposedly "cheaper" driver seems to model "better". Or is it that I don't know how to read the stats (most likely). The more expensive driver gives a flatter curve yet the cheaper drive has a louder SPL with a smaller Xmax. Is it due to the efficiencies or is it something else? Driver X: Sensitivity - SPL - 1Watt @ 1 metre: 88.17 Voice Coil Resistance (Re): 3.5 Ohms Resonant Frequency (Fs): 25.58Hz Mechanical Q Factor (Qms): 3.843 Electrical Q Factor (Qes): 0.458 Total Q Factor (Qts): 0.409 Equivalent Volume (Vas): 93.42 Lt Cone Area: 0.049 Sq m Xmax: 10.5mm Driver Y: Sensitivity - SPL - 1Watt @ 1 metre: 93.0 (note WINISD says 90.8) Voice Coil Resistance (Re): 3.5 Ohms Resonant Frequency (Fs): 21.6Hz Mechanical Q Factor (Qms): 12.29 Electrical Q Factor (Qes): 0.294 Total Q Factor (Qts): 0.288 Equivalent Volume (Vas): 220 Lt Cone Area: 0.0494 Sq m Xmax: 6.0mm WINISD says that Driver Y has a higher SPL down to 24Hz and then both drivers are approx. equal below that. I have modelled both with the following, 125 L enclosure tuned to 21.5Hz, 2 x 82mm vents - 487mm long. Driver Y has a -3dB @ 35.4 Hz and Driver X has a -3db @ 21.3 Hz, yet Driver Y is supposedly louder. Your thoughts and advice would be appreciated. Thanks, Anthony.