Nice tutorial on the Alpine Subs, I have the SWR 12d4 type r. in a sealed box. ( Being built at moment). Approx 1.3 cu.ft. Using Peters puzzle technique

I just bought a Alpine Type R2-W12D4, what sealed box volume will you recommend?

I have the same type r 12 (older 1) what amp power would you recommend for it. It's 500wrms? Thanks

Dude, that Type-R is like 20 years old. It’s an SWR-1242D. Was discontinued in like 2007. Neither of those are in the correct box. The Type-R should be in a 0.85cf gross box and the X-Series should be in a 0.97cf box. Your 1.0 and 1.5cf boxes are outside the range of those subs. F3 of the R should be 49Hz in the correct box and 36Hz for the X. Now find a Type-X from the same generation as the R. The SWX-1042D. I have the 1042D’s. They actually respond down to like 8Hz with peak output at 11Hz. From a 10” sub. Talk about low frequency extension.