TopFeatured.com

I’m new to the world of DIY speakers, and I’m thinking of building a subwoofer for my smaller pair of active speakers (KRK RP5s: 2 ways, a 5 1/4″ 30W woofer and a 1″ 20W Tweeter).

Looking here and there I came across this sub, the W6 1139 SIF from Tang Band, for which I found many positive reviews but no full project… so, I started designing my own on Winisd… or, at least, I tried :confused:
long story short:
I was thinking of a 0.883 ft3 (25 liters) ported box, with a 15″ x 0.4″ (38x1cm) port tuned @32Hz (port length: 15.5″, seems doable)
at 40W of power I should get F3 @29Hz, peak air velocity of 18m/s… but xmax (11.5mm) @23Hz.
How would you modify it? I’m going by trial&error, but I haven’t found I way to keep the driver from going in over-excursion except using the filters included in Winisd, but I reckon they’re all active (?).
suggestions? what about that f3? to me, it seems very optimistic for a 6.5″ …

Thanks a lot

p.s.: does PE ship worldwide?