IB opinions

[PoorboyMike]

Well, we're finally getting ready to build our new house and it seems the only thing I really care about is making sure the basement is mine and planning the theater and family rooms. :B

The basement construction won't happen until winter but I need to estimate how much I'm going to spend so I can pad the sworn statement and not have to come up with more money after the house is built.

I have $1200 planned for drivers, which I was going to use 4 Q18s. But, after reading comments from Mark Seaton and Kyle from TC, I'm wondering if I would be better off getting more, less expensive drivers. For $1200, I could get almost 16 MJ18's and I could put 4 in each corner of the theater.

So what are peoples opinions on this? If a person has the room, would they be better off with more drivers or better drivers? Or more better drivers. :B

[Paul W]

more better drivers

Haven't kept up with the newer drivers suitable for an IB but I've been very satisfied with the JBL recommended "symmetrical opposite wall" configuration (Google for the white-paper). In other words, if practical, I would do midpoint of the walls on each side, plus midpoint front and back. There is a lot of SPL gain available with corner placement, but you can end up with a giant boom box.

[PoorboyMike]

I wont be able to do the middle of the side walls. I'll have a false wall at the front of the theater that the equipment and back wave of the IB will go into, and a room at the back where I can mount a couple manifolds.

I've heard plenty of good things about the Harmon Paper, but being a basement, the only way I could do that would be to put the theater right in the middle. If I did that, it would take away from my family room/bar. 8O

[OttoMatic]

Part of it will depend on the size of your room. I'm using four MJ-18s in a roughly 20x17 room w/ vaulted ceilings, which opens to a foyer and a dining room. I use them in an IB configuration, as shown here. I use a Behringer EP2500 amp to power them, with the drivers in a dual parallel configuration.

This sub will get scary loud. It will literally shake the walls. It has not hit any power or driver limit, and I don't think I would want it to. In my opinion, more drivers wouldn't be necessary for any reason.

If I were going to make a change to it, I would probably buy better drivers. Don't get me wrong, the MJ-18s are a great bang for the buck, and I don't feel like I'm missing out on anything. They drop off kinda quickly at about 15 Hz or so, as shown in one of the pictures in my sig.

Actually, if I were going to try to improve anything about this sub, I might try to enclose it and port it to turn it into an LLT. There was another guy at the HomeTheaterShack that did that (turning an IB into and LLT), and it really improved the frequency response. That said, I have no first-hand experience with an LLT, but I may give it a shot when I get bored this winter...

Anyway, that's my opinion -- I doubt you'll need more than four 18" drivers, and either an IB or LLT alignment will do well for you. Better drivers might get you more, but I sure get a heck of a lot out of my MJ-18s. You probably also know that Mach5 is working on a new 18" driver that supposedly has better specs, etc., than the MJ-18. I don't know where that stands from a delivery or cost perspective, but I have heard about it.

Good luck!

[ThomasW]

I have plenty of experience with a multiple smaller driver IB's since I have two of those. Understand this is a function of necessity not choice, given they're floor mounted. In addition I've heard Cliff B's 4-Fi .Q18" IB.

And to be honest I couldn't say there was a qualitative difference between them.

I realize there's a lot of discussion regarding the fact that higher Le drivers wouldn't/couldn't/shouldn't sound as good as lower Le ones. That's great fodder for pages and pages of internet forum debate and speculation. In the real world I think the impact of 'the room' equalizes these things out, so in the end it's a wash...

With the current recommedations for Vd none of the drivers (High Le/high Xmax or low Le/low Xmax) are being worked very hard, so I think it's fine to choose either setup, and do so depending on what works best for one's particular room.

[Paul H]

... but I need to estimate how much I'm going to spend so I can ... ... not have to come up with more money after the house is built.

Good luck with that ....

[crackyflipside]

I first bought the MJ18's with the idea of an IB sub but having never heard one, I figured I was just going to leave it as a big sealed sub.

Now after hearing chasw98's IB it pretty much sealed the deal for me; I really liked the IB sound.

Although I may upgrade to 4 higher excursion drivers down the line, we are planning on building a giant center console dividing the left and right of the room for cupholders as well as a bunch of misc outlets to hook up to LAN, electric outlet, earphones, RCA, etc... Well that bottom part of the console will be unused space until I upgrade subs and make it a giant sealed subwoofer with the 4 mj18s. :E

[PoorboyMike]

Good luck with that ....

LOL. I know what you are saying, but I plan on doing quite a bit of the work myself, and paying me as if I was a contractor. I can always hope anyways!

[noah katz]

I wont be able to do the middle of the side walls...

I've heard plenty of good things about the Harmon Paper... 8O

The paper shows that two subs at opposite mid-sides is nearly as good as on all four walls; sounds like you could do that front/rear.

[fjhuerta]

One great thing about IB's - you can get away with less expensive drivers, and trust me, you'll never wish for more / better bass. I'm using 4 very cheap C-V 15" drivers powered by 2 Audiosource monoblocks (very small - 70W or so each), on a small room - about 10 x 14 x 12. I've never, ever wished for more power, and the amps have never even come close to clipping - and I'm using a Behringer FD... IIRC, I have flat frequency response to 16 Hz or so.

IB rules!

[mrogowski]

Man, I'm still jealous of you IBer's...

Best,
Mark