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DIY Newbie, Subwoofer advice needed

post #1 of 11
Thread Starter 
Hi All,

Thanks in advance for any feedback. I’ll try to be succinct but it’s not one if my strengths.

I currently have a PSA XV-15, which I like but I need more/different so I am trying to decide if I should get another, get rid of it and build my own, or as my wife sometimes says about other things (not directed negatively at me), just shut up and get over it. The biggest issues are likely: my room, my age and my budget…not necessarily in that order.

The room is about 5400 cu ft (25x24x9), and has a 5x8 opening to an even bigger space. Plus it has about 125 sq ft of windows along with hard flooring on slab. I’m asking a lot of that one PSA. The inconsistent bass depending on where you are in the room is huge and the dead spot in the middle is pretty massive as well. I’ve moved the sub several times to no avail.

My age – pushing 50 and have played guitar and been to too many concerts. A fine ear…yeah I no longer have that. On the plus side, I no longer care nearly as much now that my hearing has becoming selective and now go for aesthetics and décor more than audiophile taste. Thus I have ended up with the discontinued Mirage OS3 towers and center channel and the matching Omnican ceiling speakers for surrounds because they sound good for movies and I like their sleek look. I would say I am 80% theater and 20% music at this point but I do care much more about the theater side than I do about the music as I have a 120” screen in the room. My taste also seems to have shifted as I think I would now prefer sealed to ported, which adds to my dilemma. I’m powering these Mirage’s with an Onkyo 607.

My budget – not a huge issue but I’d really like to stay within spending what it might cost to add another XV-15. So if I do that, I’m in for about another $800+ (but if I want to go sealed, why buy another XV other than it’s the easiest thing to do). But I could sell the one I have, take that cash and add to it and build two of my own.

I see a lot on here about the SI 18, the DIY Sound Group 4 cu ft cab, and maybe adding a pro amp like the Peavey ISP2 with DSP to all that and being perhaps a little over a grand. I have little clue about Ohms and wiring this and certainly don’t want to add any dedicated breakers to the room so I’m not looking for thousands of watts but would be willing to push the edge of what I’ve got to rumble the room. So the big question is, does my room suck so much that this would end up not being a great solution anyway? I don’t want to make the walls flex at reference levels but I would like the place to shake when a T-Rex walks through the room. I have two good corners and several places to add the subs along three of the walls as well so as long as I can give them a decent finish (the black sand finish on the PSA is fine with my wife) so I can put two good size boxes in there without issue but I don’t want more than two.

Thoughts and suggestions welcome.
post #2 of 11
Four Si 18s with D4 coils, two stacked in each corner wired down to 4 ohms with a nu6000 to power them will easily give you more spl then a pair of your current subs.
post #3 of 11
"So the big question is, does my room suck so much that this would end up not being a great solution anyway?"

probably not, but reflections can cause a lot of peaks and nulls throughout the room, particularly if only using one source/sub.


"I don’t want to make the walls flex at reference levels but I would like the place to shake when a T-Rex walks through the room."

jay's suggestion is excellent, but I would go one step further and suggest that you build ported cabinets (because you have a fairly large room). a simple slot ported design wouldn't be too difficult to build and with one in each corner would provide an absolute ton of t-rex stomping power.

how much space have you got to work with?
post #4 of 11
Quote:
Originally Posted by LTD02 View Post

"So the big question is, does my room suck so much that this would end up not being a great solution anyway?"

probably not, but reflections can cause a lot of peaks and nulls throughout the room, particularly if only using one source/sub.


"I don’t want to make the walls flex at reference levels but I would like the place to shake when a T-Rex walks through the room."

jay's suggestion is excellent, but I would go one step further and suggest that you build ported cabinets (because you have a fairly large room). a simple slot ported design wouldn't be too difficult to build and with one in each corner would provide an absolute ton of t-rex stomping power.

how much space have you got to work with?
+1 ported will give you more output with the same or even less power. also many threads out there stating if properly setup only certain people can pick out a ported vs sealed design. maybe just dual Si 18's in ported enclosures with an inuke 3000 dsp? i'm getting ready to do 4 in a sealed configuration with dual amps. but i am coming from dual svs pb-13 ultras so i am expecting quite a bit from them. hope i get what i am expecting from them.
post #5 of 11
Thread Starter 
Space is not really an issue but I don't want to turn it into a room full of subwoofer boxes. I'd like to keep it to two boxes and I don't really want something much bigger tha 4 cu ft per box. If you think ported would be just as good, should I just consider another XV-15 and call it a day or would two SI 18's with the NU6000 be substantially better? Will I be OK with the NU6000 on the same curciut as the rest of my system?
post #6 of 11
Thread Starter 
Also, how big a box would I need for an 18" in a ported box? It seems like the boxes get exponentially bigger for ported vs. sealed so I either need to get a much bigger box or more, smaller speakers if I go ported.
post #7 of 11
An 8 ft3 20hz tuned box looks really good. With a 20hz high pass filter in place the driver wont have excursion issues even with 2000 watts, not sure about thermal power handling though.

If you actually planned on using 2000 watts three 4" x 28" ports would be needed
post #8 of 11
Thread Starter 
If I want to have two subs to even out the sound in the room, I'd rather not have boxes quite that big. In that case, would I be better off going sealed and being able to stay with 4 ft3 box? How much power would I need for two of those SI 18's to keep them happy?
post #9 of 11
" maybe just dual Si 18's in ported enclosures with an inuke 3000 dsp? i'm getting ready to do 4 in a sealed configuration with dual amps. but i am coming from dual svs pb-13 ultras so i am expecting quite a bit from them. hope i get what i am expecting from them."

check out data-bass.com

josh ricci tested them both.
post #10 of 11
for a si 18 in a 4 cubic foot enclosure, something around 1000 watts or a little more is good.

the ported do tend to be larger, but what you get in return is about ~8db+ more bass power around the tuning frequency and that is quite a lot.
post #11 of 11
Quote:
Originally Posted by LTD02 View Post

" maybe just dual Si 18's in ported enclosures with an inuke 3000 dsp? i'm getting ready to do 4 in a sealed configuration with dual amps. but i am coming from dual svs pb-13 ultras so i am expecting quite a bit from them. hope i get what i am expecting from them."

check out data-bass.com

josh ricci tested them both.
thanks I have looked at this extensively. But those numbers don't mean a lot to me being they are taken out in an open field. It will come down to the specific room and placement for me. But I'm sure 4 18's won't have a problem moving at least as much air as the ultras did and I'm saving a lot of money in the process
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