I am thinking of upgrading my Onkyo HTIB sub with a DIY 15" woofer build. Budget is around $400 for driver and amp with a self-made box. My room is 19'4" x 15'6 x 8' and I'd say I do 90/10 HT/music. I've got a Onkyo TX-NR609 driving a Polk CS20 center and Polk Tsi400 towers for fronts with the HTIB speakers as surrounds right now (looking at getting some Tsi200s or FXI-A4's to upgrade there). Nothing fancy but much better than the HTIB speakers/receiver.
After scouring these forums (and immediately getting shot down by the wife when I proposed building a LilMike F-20) I think I've settled on a Dayton Audio 15" HO or HF driver with a 500W plate-amp (either Dayton Audio or Bash). I'm sure people will try to talk me into a iNuke amp or something along those lines with DSP, but for my use, I think this cost/performance will be a great upgrade from where I'm at now.
I think I've got the wherewithal and tools to do a ported cabinet build with the plate amp installed into the cabinet on the back. I would possibly like to do a down firing driver with the port on the front (or vice versa). I wouldn't be opposed to a front driver/front port build but I like the idea of having the driver hidden. Given the above info, I've got the following questions:
1) Given my room size and mainly HT use, would this driver and a ported box serve as a good upgrade? (not looking for audiophile SQ, just some decent bass when I watch movies and such upstairs)
2) Any thoughts on the choice between the HF/HO/Titanic sub from Dayton (or another around the same price)? The HO is much cheaper now and reportedly favors smaller cabs and provides good HT output.
3) Any big differences between the Dayton Audio and Bash amps? (as you can see, I've gravitate towards the selection on parts express)
4) Is 500W enough to get decent home theater bass without breaking the neighbor's windows? (or could I possibly squeeze by with the 300W Bash) Budget is a big consideration for the wife and I just want a good upgrade without wasting money on a retail Klipsch or something along those lines.
5) I've been doing some modeling with WinISD and am leaning towards a 5CF box tuned to 18Hz. Seems if I throw a true 500W at it in this configuration, I could risk exceeding Xmax, But in most situations I wouldn't risk damaging the driver above ~15Hz.
6) I just want to double-check that I am interpreting WinISD correctly: Larger box volume allows me to dig deeper into the low frequencies. On the other hand, a larger box also allows more excursion which risks damaging the driver. I need to find the "sweet spot" in box size that will allow flatter low freq performance without exceeding Xmax at expected power levels. Is this a good summary of the modeling?
7) When considering a down firing driver or port, does this have any real impact on the performance of the enclosure? Or will the system perform the same given the port diameter and length and the inner volume of the cabinet?
8) When building the cabinet, do I need to brace the back panel if it has a cut-out for the plate amp in it?
9) I need an exact value on how much happier that I'll be spending 400 dollars on this than I would on a retail box. Without this precise measurement, I won't be able to decide if this is right for me.
Apologies if I've asked any questions that have been addressed ad nauseum in other parts of the forum. Thanks in advance for any advice or criticism of my approach and assumptions here. I'll try to keep up to date with any build or parts decisions I make but I can't promise anything as I'm finishing up grad school this semester. (and with my birthday and christmas coming up, the old lady frowns upon discretionary spending such as this).
Sorry for the extensive post and thanks again for all the help!