Multiple boxes, different sizes

[WarrenP]

Hey folks,

I'm going to be building a new HT soon, and the room will be pretty large. I want to build some new subs for this room. I have some general sub-realted questions.

Is there any benefit to the following:

A build that has some subs in smaller enclosures, tuned a bit higher, at around 30Hz, and some other boxes that are big, really big, and tuned really low? I'm thinking of going with 4 15s (in the smaller boxes) tuned at 30Hz around the room, and 2 18s (in the big boxes) tuned low up front.

I have lots of room up front, and could redesign for room in the back. Is there a benefit to having different boxes like this, or should I just make 4 big boxes for the 18s, and leave it at that? On the flipside, am I introducing problems with the multiple box / multiple size design?

I think that in my builds I'll be going with SS drivers, so my followups will be about those drivers and related amps...

thanks!

[Warmon]

Wow, that's a whole lotta base!!! How much cubic feet in this room?

Warmon -

[WarrenP]

The rough dimensions of the room are approx 11' x 18' x 30' so around 6000 cubic feet. Once properly framed in, and with the stage and risers, that volume will decrease a fair amount though.

[Owen Bartley]

If you have some flexibility in your room size, why not wall off a section of the front (ie take a slice off the length of the room) and turn it into an IB? You could also mount any equipment in there if you wanted to.

[WarrenP]

Owen Bartley wrote:

If you have some flexibility in your room size, why not wall off a section of the front (ie take a slice off the length of the room) and turn it into an IB? You could also mount any equipment in there if you wanted to.

I could do this. In fact, I've thought of building a big IB-ish box in the front, and another in the rear, for 4 18s. I'm trying to find out if there is any benefit to doing something like that, plus a few boxes that are tuned higher. If there really isn't any benefit, then I will probably just go with big boxes in front and in back.

[Warmon]

WarrenP wrote:

...I'm trying to find out if there is any benefit to doing something like that, plus a few boxes that are tuned higher. If there really isn't any benefit, then I will probably just go with big boxes in front and in back.

I would like to know this too. How about multiples of sealed and ported boxen?

Warmon -

[Owen Bartley]

I'm not an expert, but I think that the more woofers you have in multiple positions, the more you will run into cancellation and other issues. Maybe you'll even overcome cancellation and take care of any room nulls as well with a bunch of different locations, I'm not sure. But I think the general method right now is to place a sub in the room at your listening position, and move around the room to see where you get the fullest bass, and that is where you should locate your sub (or IB). The other way of doing this is just sitting at the listening position and moving the sub around and trying it in different locations until you find the position that gives you the best sounding result.

[a1161979]

Owen Bartley wrote:

I'm not an expert, but I think that the more woofers you have in multiple positions, the more you will run into cancellation and other issues.

Correct, not to mention phase interaction issues that could result in cancelation of certain frequencies

I also do not see the point in 15 inch woofers with 18 inch woofers, trying to intergrate those would be a nightmare not to mention it would be un necessary, you should be looking to buil a LLT with 18 inch drivers, ir an IB depending on which side of the fence you stand!

I presume that the reason for 15 is as a bass driver to provide the punch between 40 and 150 hz? What are you mains, they should produce enough bass to a level where the LLT/IB would take over say at around 60hz!

15's and 18's different positions/boxes = NIGHTMARE aka dont even think about it... This is home theater not PRO sound... You do not need Kick bins in your home theater and if you do you need new mains