DIY sub help

Hi everyone, newb here.

I've been reading/searching here for a while and it seems the more I read, the more confused I get. I have built myself a little man cave HT in the corner of my finished basement. I currently have a 3.0 system and would like to add a powered sub. I was flip-flopping between retail and diy. But I've settled on diy for bang/buck reasons. My budget is between $400-$500. (less is OK) I'm confident in my woodworking skills. Size isn't a huge concern but I don't want anything outrageous, 8ft^3 is probably the biggest I'd want. I expect clean (not boomy) bass that you can feel and not hear, but I understand the limitations of my budget.

I was considering dual 12s or maybe a single 15. But I'm getting in over my head and I could use some guidance with regard to drivers, sealed vs ported, amps. I don't want to make a $500 mistake and have to start over.

I attached a simple floor plan (not exactly to scale) of the basement room(s). The HT area is on the right side of a long room which is open to smaller room and a stairwell. The walls are covered in sheetrock, the floors are padded and carpeted. The ceiling is a combination of suspended tiles and sheetrock. I labeled 3 spots a subwoofer might fit, 3 is the tightest fit with the current couch.

Current setup: Polk CS2 and M70s / Onkyo TX-SR709

Intended Use: 40% TV, 20% movies, 40% games, 0% music.

Room info: ~3500 ft^3

Basement HT.pdf 12k .pdf file

thanks in advance

Tom

edit for clarity
Edited by tommy1403 - 11/26/12 at 12:12pm

Thank you for the replies. What are the size requirements for an LLF box? (I can't seem to find any plans) I see you're both suggesting external amps vs plate amps. is that for cost savings or for increased power? I hadn't considered external amps or processors as I don't have anywhere to mount them. (media console is full). I had notions of a bash plate amp and dayton 12s or 15s.

I have been tossing around the idea of an Epik Legend now that it's on sale. I just don't think it will be enough for my room.

what's wally world?

haha, I am hoping he wasn't talking about buying a $300 amp at walmart.

walmart, who knew?

There really isn't space for future upgrades or sub additions, at least not while we're living in this house. So this will be it for the next 5 years or so.

As for DSP and REW, I thought the ONKYO would EQ the sub with Audyssey. That's what i read, which is why i got the 709 vs something cheaper. Or is DSP something different? I'm with vivatech here, kinda lost.

I think i should reevaluate my expectations for this endeavor. I really just want a sub or 2 (at most) to make my HT experience more complete. Instead of spending a lot on an Empire or Outlaw, I was hoping to get something close by DIY. The more I think about it, the 8 cube box is going to be too big. I would rather have 2 smaller boxes in the 4 cube range

I'm just trying to be realistic with what I want to accomplish. A few months ago I was looking at a single BIC F12, then a PA-150. Now I see I can do better with my money.

Great, that sounds like a plan. Would those boxes be sealed or ported? Could you direct me to a previous build I could learn from? thanks again

thanks, ngc. Does it matter if the boxes are front or down firing? I've been playing with WinISD, it's pretty cool.

OK, I want to make it as future (child/dog) proof as possible, down firing will hopefully help that. I am looking to modify Rhythmik's free DIY plans into a 5 cube box with the correct port size and length. Would that work? Does it matter if the ports point down or forward?

Bill, I am not very adept at modeling. But I'm becoming more and more familiar with WinISD. I played around with modeling a bandpass box (both 4th and 6th order) with the front chamber as the area between the cab and floor? I'm sure that was the wrong way to do it.