IB subs. Has anyone built one?

Ron-P

In an effort to remove the big black tube in my HT I was contemplating building an IB sub. Has anyone done this?

Dr. Spec

Yes, check my thread history. I posted pics of a twin AV-15 IB I helped spec and design. I can even get the build plans on AutoCAD if you have that capability. PM me and we'll coordinate from work where I have the files.

The transition box is so strong, it would support a car.

You might need twin Tempests to get the same output as your sonotube.

Ed

goingganzo

i would say go for a ib i would love to but with my setup i cant.

Ron-P

Thanks Doc but I cannot support AutoCad. No problem adding a second Tempest, in fact, that is what I was planning to do.

My biggest concern is placement. Don't have too much room in the garage to have duel 15" speakers sticking out.

But, something must be done as my Sonosub is sitting directly infront of my AC unit and blocks the air flow so I must move it to one side during usage, kindaof a pain.

I'm willing to give it a try but I'm concerend that I won't get what my Sonosub is giving me. This will be a Summer project, no time over the next couple of months plus I've got to finish my new screen.

tryrrthg

Everything I've read about IB's says that an IB will CRUSH your sonosub in terms of bass quality. Quantity will depend on the number of drivers, but I'm guessing a two tempest IB will put out quite a bit of SPL.

You can mount the IB as an "outtie" meaning you could have the square box inside the theater and vented into the garage. that way you get the bigger sonotube out of way and don't waste any space in the garage. Check out this guys "outtie" (first one on the page linked below):

http://home.comcast.net/~ttriff//page4IB-Gallery3.html

You may want to surf theCult of the Infintely Baffled they'll be able to help for sure!

faster100

so the hole or vent doesnt have to be that large in the wall.. basically build the whole enclosure in the attic and have an A/C vent just showing in the ceiling would work? and does it make the whole ceiling rattle though? interesting link and pics.. I have a full sized attic, not crawl space..

tryrrthg

Originally posted by faster100
basically build the whole enclosure in the attic and have an A/C vent just showing in the ceiling would work?

Yes, that would work great!

As long as the front wave is seperated from the back wave it will work. an IB is basically a sealed sub in a VERY large box.

It will vibrate the whole house if you play it loud enough. I believe mounting the drivers on opposing sides helps defeat some of the vibration by cancelling some out.

Dr. Spec

Ron, I can mail you a set of plans, if you want, let me know.

Yes, an external transition box is really the only way to go. The opening to the box is in your Driftwood, and the drivers and guts hang outside in the garage.

I wouldn't say the IB will "kill", the sonotube. It has a different flavor of bass presentation - a bit on the soft side. That is also affected by the Q of the driver, which should be around 0.6-0.7 for a HT/music application.

The Q of the AV-15 is around 0.4 as we wired it, and it was pretty "dry" but transient response was excellent and cone control is great. We recently upped it to 0.8 and it hits a bit harder now.

FR is flat to 10 Hz, and really the only limitation to volume in the infrasonic region is cone excursion, as it will be ridiculously easy to drive the woofers to bottoming before you ever reach the thermal limits of the VC.

IB is easy and cool if you want something different. But don't expect it to "blow away" the bass quality of the sonotube. It will be different, but not necessarily a ton better. It won't sound bad, I'll tell you that much.

Ron-P

If you don't mind Doc, I'll take'em. Let me know the cost and I'll gladly send it. For the simple and easy build this is something I want to try. Hey, if I don't like it, I can go back to my Sonosub and patch the hole in the Driftwood.

Dr. Spec

Ron:

PM with with your addy and consider it done. No need for $$. I'll print them on 8x11 or 11x14 - whatever works better.

Ed

Jstas

Now this right here:

Is THUNDER IN A BOX!

tryrrthg

Originally posted by Jstas
Now this right here:
Is THUNDER IN A BOX!

Yeah, and he has 2 of those, 18 drivers in all! :eek:

Ron-P

Doc, received the plans yesterday. Thanks!

Here's a reply email from Adire on their Tempest. Looks like I'll add another for this project. I cannot see needing more then two drivers for my small room but I'll build it big enough to add to if needed.

Hi Ron,

Thanks for the email! The Tempest works extremely well in an IB
application because of it low resonant frequency, moderate Qts and very
long excursion capabilities. I would take a look at what Rich Kraus' IB
our DIY gallery 9
http://www.adireaudio.com/diy_audio/gallery/tempest_territory.htm). HE
ran a coil open on each driver to give him some added bass extension and
also give a 4 hom mono load for a pair of driver, but you can also run
both coils of both driver or go with an RDO setup for somewhere in
between. (http://www.adireaudio.com/tech_papers/rdo_operation.htm)
Yes, in order to match the output of your big vented tube, we'd
recommend that you add a second driver. However, one of the nice things
about an IB is that it takes very little power to get the most out of
the drivers down deep. In the case of the Tempest, you only need
100-150 watts to get the most out of the driver. Also you may consider
building your manifold/transition box with room to expand if you ever
decide you want more output (i.e. room to place another pair of drivers.
Please let us know if you have any other questions.

Thanks,

faster100

can i make a simple 1 driver IB sub? I was thinking one driver in my attic for my 2 channel rig, out here is all wood walls, It used to be a porch i think, I have a few amps, could you run a dual voice coil sub and run 2 channels from amp to each coil? and then just have a a/c vent cut in the ceiling for the vent, how do i do this, where are the drivers available and would i need some kind of crossover?

tryrrthg

A one driver IB will most likely bottom out way too easy. You'd want at least two to get good SPL. as far as drivers go, check out

www.adireaudio.com
www.partsexpress.com
www.acoustic-visions.com

Parts Express sells some IB drivers that are pretty cheap and do a very good job, from what I've read. For a two channel rig you'd probably need a crossover if you're not using a receiver.

Dr. Spec

There's an IB thread at HTF Speakers/Sub (the guy tried to use a single original SVS 12" driver - not the smartest move) and I posted pics of that IB we designed and built using those plans. I think you'll be fine using another Tempest in the Driftwood. It's a small, tight room, and the Tempest is a great driver. the IB "sound" integrates very well with the speakers; I think you'll like it.

Ed

Ron-P

One concern I do have is the sound outside the theater. Currently, there is none, with the loudest, hardest hitting bass I can produce inside the theater is barely heard inside the house.

With an IB design and the drivers outside the theater how noisy will this be? I often crack open the garage door to allow for fresh air venting through and exhaust system I built. The drivers will most likely be mounted near the front of the theater, by the garage door.

tryrrthg

I'm pretty sure that the sound outside the theater will be as loud as inside.

Ron-P

That's my fear and if so I won't go IB.

Dr. Spec

Then just build a really large box around the back of the IB to insulate the sound. It won't be a true IB, but it will be damn efficient and deep, regardless.

Ron-P

Now that's a do-able idea. Hmmmm, me thinks I might have to try this. This will make for a fun summer project. I'll post pics as I move forward and build it.

audiobliss

I'm not interested in making one of these subs, but I am interested in how they work. I always thought that subs had to 'pressurize' the room ot be effective. I guess to move more air molecules and, I guess, be louder. Is this wrong?? And, if it is right, how in the world do these subs pressurize the room? It appears to me that since there is no box containing the drivers, nor a box into which the drivers radiate, that they wouldn't be able to pressurize anything. Or, is that why there are so many drivers?? Based on the principle that if you get enough, you can pressurize anything??

I'm just a little confused on this one.

Thanks.

tryrrthg

an IB is just a VERY VERY large sealed box sub. It's no different than making a GIANT box sitting inside your living room. The IB works just like a sealed sub, but with the added drivers and room gain you get the SPL and extention of a ported subwoofer.

IB FAQ

burdette

Hey Ron.... how much room do you have on the top of your theater room in the garage? I had two ideas concerning your situation...

1) maintain your traditional ported design, but have the enclosure on the top of the theater, with the woofer and port opening into the ceiling. You don't need THAT much vertical clearance and can get your volume by spreading out the enclosure.
1a) you could also do this along-side the theater... build a box enclosure only as thick as necessary, then make the height and width enough to capture your volume. The woofer and port open directly through the wall.

With either one, make the enclosure walls double and put either insulation between, or, as was suggested to be by Stryke for a REALLY dead tube.. fill the space with the expanding foam insulation. (Stryke recommended a double-tube... like 16" and 18".. one inside the other with spacers, then fill in the remaining space with expanding foam.)

2) do you have "house" over your garage, or is it attic? You could put the woofer in the ceiling of the theater and build a connecting enclosure from the roof of the theater up to the ceiling of the garage, then open into the attic. Make it stiff and wrap insulation around it.