For such low frequencies, even a very crude exponential flare will work fine. Start with being as tight as possible to the woofer. Without having all the specific dimensions, it's hard to be more helpful than that. You want the mouth opening to be as large as possible. Just bend some plywood to a curve from the source. At the low frequencies you're using, even straight sides will be ok.

 

I checked your room's transfer function, and it appears you're not going to need much, if any EQ http://www.klipschcorner.com/Tools/ModeCalc.aspx. Compare your 16x16 estimation to the actual measurements to see why I said what I did about the room mode.

Because of this, you're one of those fortunate people who'll be better off with a corner-loaded sub, IB or otherwise. Mounting along the center of a wall will result in non-uniform excitation of these room modes, and a reduction in overall output.

 

thanks guys. since the horn isn't as complicated as i was imagining i'll go ahead and do that. as far as the room placement. I understand that i'll be better of corner loaded but well the sound suffer dramatically if it's in the front center under the tv? I have a few reasons for wanting it there. 1) can't move the fireplace 2) centered between the speakers (if i go with some cube speakers or something that doesn't reach down as deep as my current def tech's, that'll be an advantage) 3)asethetics.

with that in mind. what wins out:
a single 12 or 15 in box with say 500 wrms corner loaded ( http://www.partsexpress.com/pe/showd...number=300-762 or http://www.partsexpress.com/pe/showd...number=300-764 )
v.
two 15" IB dayton's with the "1400" wrms to the pair in the center of the room

in the comparison please keep factor in the sat. speaker option

 

Horn loading will somewhat make up for not being corner loaded.

 

Mini hijack, but question on the transfer function. In my next living arrangement it appears that my 24"x24"x30.5"H sub is going to go in a closet as the front room is just to small to support it. Closet will be 27"x26"x8'. How bad is this?

BTW enclosure is tuned to 18.8hz and has 1000w RMS to it on a 15" Adire Tempest. Thanks in advance

Fej

 

The closet part has too many variables to address properly. It will depend on the playback range and whether there are issues relating to buzzing or rattling that will make the sub easily locatable by a listener. The closet dimensions themselves are too small to have a direct effect on the sub's response, at least in terms of modes.

The room, on the other hand, might give you fits. Everything depends on the room's dimensions and the coupling of the closet sub into that room.

Last thing... a tuning frequency of 18 Hz does not mean that the sub is flat down to 18 Hz. There are a ton of variables, and usually the actual rolloff begins higher than the tuning frequency, but lower than the equivalent box resonance.

 

It sounds like the sub is an almost perfect fit in that closet. As long as it's in a good location. Mount the sub so the face is flush with the outside wall and fill the voids on the sides and behind. Ideally, you would fill it with sand and you will have a great undistorted output, free of early reflections. We do this in high end studio installations, including the full range boxes inserted into speaker soffits.

 

ok, you got your answers..back to me :-)

when i horn load the subs do i set up a horn for each sub? or one bigger one.

for instance:
\O/\O/
or
\OO/

 

Again, depending on the dimensions you have to work with \0/\0/ would probably work best but I might try to go one step further by putting the subs on the sides and use a folded horn configuration. You can get a lot more use of the space. If you want to tackle this job seriously, there are a number of sources for further kowledge. If I find some links I'll post them.

 

i don't have the clearance for a 15" woofer; though a folded horn would have been cool, i'm only working with about 8" of verticle space. The woofers are going to have to lay horizontal. I have the contractor guys coming in this morning so I think i'm going to have to settle for the \O/\O/ design.

Thanks again for all your help

 

How wide is that going to be? If the area of the mouth opening isn't at least 4 times the area of the speakers themselves, there will be little benefit. If it's really small, you may even get more performance from a single sub.

 

the opening will be 8" tall by 72" wide

 

You will probably not get much gain from the horn effort but it won't hurt and you'll have wow factor. You will get some gain but most of it will be at frequencies above your sub cut off.

 

ah, ok. i hope this will give a good low end extension for my home theater set up. hopefully i didnt just waste a bunch of money :-\

 

You'll make it work. It'll rock you with two 15's either way. There is still about double the mouth opening, just not ideal.

 

Just an update, i've had the IB setup for about two weeks now and it's great. I have some rattling issues when i really push it hard but nothing a tube of liquid nails wont solve. I've been testing different speaker configs and they all sound pretty good. I have a pair of mini cube tang band diy speakers that; after breaking in for a few hours, sound very very good. a lot better then bose, just a little bigger and a lot cheaper. Then i have some older polk rm mini sats that actually dont sound as good as the diy speakers but that could be a tuning issue. Then i hooked up my def tech bp10 towers and wow...that really did wonders... too bad they are just too big for the room now though.

anyways, just thought i'd update everyone. my final setup was two dayton 15" ib subs and the behringer ep1500.

thanks guys for your help

 

i just realized i never posted my final setup.

here it is in the mid stages of the build:

and here is the final product:


This thing POUNDS and it's tight too. It's only at about 1/4 volume on the amp. While watching Batman Begins, during the explosions you can feel the vibrations through the couch. The first time i watched it I laughed my *** off! It sounds really nice with music too. For the time being I only have the little test diy cube speakers and It's still pretty impressive. I have some Def Tech bp10's that i may hook up too, but they kind of take up too much real estate to justify them.

I have to lower the tv a bit (and i think i may get a 50" soon... the 42" seems a bit small now) and get a fireplace screen and this project will be a wrap.
there are no components in my room either. I have all of them hidden in a closet in the hallway and they are controlled via an i/r repeater that you can see in the second pic (it's in the wall plate) I am controlling everything with a logitech harmony remote. I highly recommend the remote for one touch opperation. I set up macros so i can press 'watch dvd' and it turn on my reciever, my tv, and the dvd player. It then switches to the correct input on the tv and reciever. when it's all done with that it even dims the lights.

anyways, thanks again for the help.

 

I was starting to think this had died. I'm really glad this worked out for you, Scott. Very nice integration, too.

That's a Polk issue.

By the way, what ever happened with the Behringer 2496?

 

thanks.

the 2496 is installed but i had an issue getting the digital out to work on my pc. while i was troubleshooting my battery died (it was low and i'm a moron for not charging it while i troubleshot) The digital out is working now and I hope to get it hooked up in the next couple weeks. I dont have any free time lately so It's just a matter of getting out to the garage. my poor car!!