Originally Posted by dgage
So for 80% home theater, I'm trying to figure out if I should go with the DIY equivalent of 3 F15HPs or 3 FV15HPs. Can anyone characterize the sound quality differences between the F15HP and FV15HP (one port mode)? Also, at 15 HZ, would 3 (or 4) F15HP equal 2 FV15HP. I am looking for clean, accurate, deep bass at decent output levels (near reference?). Call it headroom as I'm not sure I would use that much output but it is always nice to have it on tap than not.
I think this old post from Brian will help you out:
Just by eyeballing it, it looks to me like the FV15-1port has about 6dB more max output than the F15 between about 12Hz and 15Hz, which is where it has the biggest lead. HP versions of each will just add 2dB, so the relative difference is the same.
IIRC, stacking two identical subs should give you +6dB over a single, so two collocated F15HPs should roughly equal a single FV15HP in max output at 15Hz. If they aren't collocated then the answer is less cut&dried, but what you give up in max output at one frequency, you should gain in smoother frequency response.
Without knowing what kind of max SPL you need and how far away the subs will be from your listening position, I can't say whether 3 F15HPs will be enough for you. But, I'd suspect you'd have no issues unless you listen crazy loud or sit crazy-far from the subs.
For reference, my room is about the same volume as your room+kitchen (plus I have openings to the rest of the house), I have a single F15 about 11ft from my MLP, I listen at -10dB max, and I have never felt a lack of output. My ears give out before the sub does.
I can't comment on F15 vs FV15 from experience, but I expect the sealed versions to have a slight edge in sound quality over the vented. Assuming you can hit the output levels that you want with sealed, I'd lean that way myself (and have).
Hope this helps,