Alright, Ive heard alot of different things about whether a smaller or larger box will give me best SQ, which is it? The way I originally thought was the bigger box would yield a flatter fq. response curve thus giving better SQ, and the smaller box would have higher internal pressure when powered exactly the same, thus higher SPL, but i have heard the exact opposite much more often...so whos the retard? Thanks
Totally dependant on the subwoofer used. General rule of thumb, Qts of .4 and lower is best in a ported or small sealed box, Qts of .4-.7 is best sealed, .7 and above is best for infinite baffle. WinISD will give a good idea, a .707 Qtc is considered the optimal balance of transient response, bandwidth, and power handling.
A smaller sealed box is better for SQ. A larger box will give you a lower frequency extension, but will sound more "muddy" and "boomy". You generally want a box with a Qtc lower or near .707
You could however build a good ported box that will sound just as good as the sealed box and gain slightly more SPL. If it is designed right and tuned low enough this is usually my preference.
Simply put, you have a compromise. If the box is too small, it will be very boomy, will resonate at a higher frequency, and the resonance will be very peaky (large spike in response). Good for SPL, bad for SQ. It will increase power handling, but efficiency isn't as good with low power and the transient response won't be good. Box too large could lack mechanical control, but transient response is excellent and bandwidth is large. Resonance will be flat and not a bad peak, but SPL isn't as high in this case. In the end, the subwoofer's suspension will decide which is better. If your sub has a loose suspension, strong motor, low mass, it will work better ported or small sealed. Tight suspension, higher mass, or weaker motored subs need a larger sealed or IB application.