hows it going fellas?
i bought a Alpine Type R 1521d and was wondering what box sizes you recommend? ported? sealed?

i found a prefabbed ported box thats is 2 cubic foot for $140 you rekon that would be ok?

if anyone could get me a design or the right size box it would be very appreciated...

thanks

Factory recommnedations:
sealed box volume: 1.3-2.5 cubic feet
ported box volume: 1.5-3.0 cubic feet

i'll have to chase up the relevant thiele-small specs - Fs, Qts, Vas - and model them. if you have the specs, post them up; they are required to design a box.



ok, the specs i have are:

*Fs 23Hz
*Qts 0.38
*Vas 98L

it will probably sound a bit better in a 'sealed' box, although ported is ok. if you have enough power on tap (ie: high quality monobloc, 500+WRMS on tap) i would go 'sealed'; this will retain accuracy and loudness, no probs. a weaker amp would benefit from ported cos if the added efficiency, or if you enjoy loooow, phaaat subbass.

*sealed: 1.5cuft
*ported: 2.5cuft tuned to 25Hz (eg: single round 4x18.5" port)

2.0cuft for a ported box is verging on 'too small'; especially if that's the 'gross' internal volume. meaning once you add the sub and new port, the 'nett' internal volume will be less than 2.0cuft, and maybe 1.7~1.8cuft (definitely getting small then for this sub). but 2.0cuft nett tuned to 28Hz will throb hard (eg: single round 4"x18" port).