Infinite Baffle. Best bet if possible?

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I'm having a house built and the upstairs loft will become a theater. Which means I'll have the entire attic above me.

So I'm thinking the best best (and least intrusive) would be to do an infinite baffle system.

I'm thinking 4 Dayton IB 15" and a 250W plate amp should be plenty....this would be for a 15'x20' or so entertainment room.

WinISD shows these should hit about a 24Hz F3 with 100+CuFt of air behind them, which the attic should do no problem.

So is infinite baffle the best way to get effortless bass? It would definently have non parrallel walls in the enclosure :D . I'd probably do (at least) a 24dB low pass at 80Hz or so.

heres the room so far :)

An externally hosted image should be here but it was not working when we last tested it.
 
Hi

Well im no expert but it definately seems like plan to me :)
Also because of the such low qts it may be a good candidate for linkwitz transform (or equivilent)

One thing that does spring to mind however is the air leakage between the 2 rooms, because the enclosure is so damn big im reasonably sure the effect will be reduced considerably, but maybe someone who actually knows something should comment on this?

I'm having a house built and the upstairs loft will become a theater
Mmmm custom house, customised for audio! I think u are living everyone on this forums dream :eek:

Cheers, Nik
 
This is a perfect candidate for an Archectural Horn (15HZ to 80HZ).

Example:

It could be tucked into the right corner -- two of its sides being the roof corner. It downfiring mouth could be 3' x 10'. Its length would be 18'. IMO you would have the HOLY GRAIL of subwoofers and everyone on this forum would hate you :D
 
I had a infinite baffle system in my floor, so i dont know if this helps, but your subwoofers will cause problems with your plaster board, i believe it can damaged the plaster on your ceiling as the infinite baffle transfers alot of energy into the baffle,IMO, i would enclose the drivers, the rear of your drivers will get filthy and all that dust can get into the magnetic gap, if your drivers have vented pole yokes, you could add a small mess with a cotton fabric across its.
You could do much better than a infinite baffle system, not that its bad or anything, but you have so much space and access to do something really special,Good luck.
 
Yup, looks like a plan to me. My only caveat would be instead of putting a long shallow manifold on the side there, instead put a 24" (or whatever the spacing between those rafters is) cube there instead. You will be able to tie it into 3 rafters including the double thickness one. Having the drivers mounted across from each other will reduce vibrations transmitted into the rafters, but looking at that general area, I don't think it will be a big problem. I will agree with Paradise about putting some type of light cloth covering over the structure to keep out the dust. Damage to your drywall should not be an issue, I would recommend making you or the builder secures the drywall with both construction adhesive and screws :att'n: NOT NAILS :att'n: to secure the drywall to the studs and rafters, especially in that room. Other than that, remember to go ahead and run a couple lengths of good quality speaker wire through the walls from the sub location to wherever you plan to put the electronics - amps do not go in the attic. :hot:

Oh, and the Cult Forum linked in an above response is a wonderful reference, ThomasW would be happy to answer just about any questions you have.

Enjoy.
 
Fourdoor,

You have a great opportunity to have the finest quality bass available.

HERE'S a link to the IB installation photo gallery. You'll see dozens of ceiling mounted designs. They work very well.

Drop by the 'Cult' forum if you want to discuss your ideas with people that have years of experience with this particular type of sub.

Regards
ThomasW
 
Hybrid fourdoor said:
I'm having a house built and the upstairs loft will become a theater. Which means I'll have the entire attic above me.

So I'm thinking the best best (and least intrusive) would be to do an infinite baffle system.

I'm thinking 4 Dayton IB 15" and a 250W plate amp should be plenty....this would be for a 15'x20' or so entertainment room.

WinISD shows these should hit about a 24Hz F3 with 100+CuFt of air behind them, which the attic should do no problem.

So is infinite baffle the best way to get effortless bass? It would definently have non parrallel walls in the enclosure :D . I'd probably do (at least) a 24dB low pass at 80Hz or so.

heres the room so far :)

Very nice Hybrid. Nothing like getting to wire/build from the construction phase. I suppose, you will have a nice workspace (garage) now too?

Have you considered doing in-walls for all your channels of the home theater? It seems your front L/R mains are decently centered between the studs. A Morel MW166 (0.61 QTS)/MDT20 TMM/MTM would do nicely.
 
WinISD shows.....
WinISD doesn't accurately model the performance of a true IB.
I'm thinking 4 Dayton IB 15" and a 250W plate amp should be plenty
Might want to look at a slightly bigger amp. You'll basically have a world class sub, let's give it some decent power. 500 watts or so would be nice. Also plan on adding a Behringer DSP1124P to flatten any peaks
So is infinite baffle the best way to get effortless bass?
Those that have replaced their box subs with IB's certainly think so...
It would definently have non parrallel walls in the enclosure
Nope not necessary. You can make a perfect cube if you want. No problems with standing waves given the very short dimensions of the 'box'.
 
ThomasW,
Looking through the pics, none of the 2 driver setups are push pull alignments. Is there something about IB making push/pull not beneficial for distortion reduction?

Hybrid,
4 of those 15" Dayton OB's aligned in pairs (like the pics ThomasW linked in) to reduce vibration should work great, but I'd go the extra step of push/pull alignment to get the distortion reduction. I also understand that mounting them in pairs as pic'd reduces the effective Fs. I'd mount them in the rafters over the screen. However you choose to implement it you'll end up with an impressive sub.
 
Hey Hybrid Fourdoor,

Do you have ANY idea how jealous you make all the rest of us????
:bigeyes: :bigeyes: :bigeyes: :bawling: :bawling: :bawling: :smash: :smash: :smash:

Anyway... :bawling: ... Have you checked out these?
http://www.passdiy.com/projects/el-pipe-o-1.htm

With all that room to spare above your head, you could let the inner cealing material go up along the "naked roof", and have the vertical beems visible and free (like I have at home). This way, you'll have strong mounting facilities and an (in my oppinion) nice look to the room. The pipes could then be mounted like two evil exhausts above your head.

Just my 2 cents -
Jennice
 
You can try something like a Linkwitz W-frame (2, since you are considering 4 drivers) with one side screwed to the wall or ceiling studs/joists.

http://www.woodartistry.com/linkwitzlab/woofer.htm

If you're living in America or Canada, the studs are supposed to be 16" center-to-center, I think, so it would work out perfectly, since the W-frame shown on that page is 16" wide.

EDIT: Try to pick spots that are the same distance from the listening spot as the speakers, to minimize phase difference. Time to pull out that high school math! :p
 
JohninCR,

Although push-pull mounting is of course an option; people don't want to deal with trying to hide the reversed driver, if the IB is mounted on a simple flat baffle.

Most people are so stunned by the improved sound quality when they upgrade to an IB, I imagine they don't give consideration to the potential for possible improvement. And although measurable with test equipment, I question how audible the benefits of push-pull subwoofer (let's say 80Hz and below) are with modern loudspeaker design.

Finally if the drivers mounted are in a manifold, the 'ideal' situation is for there be no obstructions inside the box.

454

There's no benefit to using a "W" frame over a manifold. Actually the "W" fame will have lower output as compared to the drivers being mounted in a manifold.

I've done a IB vs dipole comparison. I have a 4-12"s IB in my family room. To match it's impact with dipole takes 8-12"s, and they don't dig as deep as the 4-12" IB
 
ThomasW said:
JohninCR,

Although push-pull mounting is of course an option; people don't want to deal with trying to hide the reversed driver, if the IB is mounted on a simple flat baffle.

Most people are so stunned by the improved sound quality when they upgrade to an IB, I imagine they don't give consideration to the potential for possible improvement. And although measurable with test equipment, I question how audible the benefits of push-pull subwoofer (let's say 80Hz and below) are with modern loudspeaker design.

Finally if the drivers mounted are in a manifold, the 'ideal' situation is for there be no obstructions inside the box.

454

There's no benefit to using a "W" frame over a manifold. Actually the "W" fame will have lower output as compared to the drivers being mounted in a manifold.

I've done a IB vs dipole comparison. I have a 4-12"s IB in my family room. To match it's impact with dipole takes 8-12"s, and they don't dig as deep as the 4-12" IB
Oh, I wasn't suggesting he use the W-frame in a dipole application, if that's what you thought. I merely recommended it to reduce distortion (when one diaphragm fires toward its magnets and the other fires away). The rear wave would be sealed inside the attic.

EDIT: If it were a dipole sub, he would have to aim the frame at the listening spot because of the cos(a) directivity pattern. Not very simple. I don't see how you thought I was suggesting a dipole W-frame?

EDIT2: And a dipole W-frame mounted to the wall or ceiling is simply ridiculous.
 
ThomasW

Most people are so stunned by the improved sound quality when they upgrade to an IB, I imagine they don't give consideration to the potential for possible improvement. And although measurable with test equipment, I question how audible the benefits of push-pull subwoofer (let's say 80Hz and below) are with modern loudspeaker design.

Kudos to you, your passion, your website, and the wonderful detailed pics of obviously hi-end audio in hi-end homes.

Per chance have you had the opportunity to compare IBs with Architectural Horns (80HZ and below)? Comments? I thank you in advance...
 
ThomasW,

I use alot of cheap drivers and push/pull with cheap drivers makes an audible difference, IMO.

Am I correct in understanding that the 2 driver "manifold" alignment lowers Fs?

Regarding the "ideal" of having no obstructions in the manifold space: Is that really true as long as it's not so tight as to restrict air flow. I'd think that having something preventing the cones from pounding directly at each other would be another benefit of push/pull using a manifold setup.

Hybrid,
In addition to eliminating vibration with the manifold setup, it also gives you vertical mounting of your drivers which will give them a longer life and higher output than horizontal mounting.
 
JohninCR
Am I correct in understanding that the 2 driver "manifold" alignment lowers Fs?
Nope. Basically the manifold funtions something like a compression driver, it creates a high pressure zone. There are no changes to the T/S parameters of the drivers

Another problem is that trying to put outside and inside mounted drivers is a small compact manifold is a nightmare. One of the people posting on the Cult forum played with the idea and after a while he just gave up.

I'd think that having something preventing the cones from pounding directly at each other would be another benefit of push/pull using a manifold setup.

????

Two things. First one doesn't want obstructions in the manifold due to the potential for 'chuffing' at high output levels. Second it doesn't matter if they're mounted push-pull or all front mounted into the manifold, the cones are mechanically in-phase.



qi,

and the wonderful detailed pics of obviously hi-end audio in hi-end homes
Thanks.... actually with the exception of less than 1/2 dozen or so examples, most of the IB's in the gallery are in middle-class homes.

Per chance have you had the opportunity to compare IBs with Architectural Horns (80HZ and below)? Comments? I thank you in advance
No, that would be a pretty tough comparsion to make given the nature of the two designs.

I've been building speakers for 40+yrs. Some of my first designs were large horn systems using 15" Altec Lansing drivers. And sorry; but as soon as reasonably priced high output power amplifiers became available, I said good-bye to horn loaded enclosures.

Note that I certainly understand the 'appeal' of these systems, but prefer a different solution...........
 
ThomasW said:

Nope. Basically the manifold funtions something like a compression driver, it creates a high pressure zone. There are no changes to the T/S parameters of the drivers

Doesn't the higher pressure (or vaccum on the backstroke) essentially give a similar effect as adding mass and thus lower the Fs? Is seems to make sense to me and I remember that a small manifold is necessary to lower Fs.

ThomasW [/i][B] Another problem is that trying to put outside and inside mounted drivers is a small compact manifold is a nightmare. One of the people posting on the Cult forum played with the idea and after a while he just gave up. [/B][/QUOTE] It's easy said:
Two things. First one doesn't want obstructions in the manifold due to the potential for 'chuffing' at high output levels. Second it doesn't matter if they're mounted push-pull or all front mounted into the manifold, the cones are mechanically in-phase.

Not wanting chuffing definitely make sense. I'm not sure about the second part though. I'd think that 2 opposing pressure fronts with one being uniform (the front facing driver) and the other being diffuse could actually be less problematic.
 
johninCR:

An IB sub with manifold mounted drivers doesn't change Fs because the manifold opening isn't a restriction to cone movement. If it is, you would be talking a bandpass alignment, and that's a different ballgame entirely. So, if you find this to be the case, your opening isn't big enough. :)

As to your other ideas, I'm not sure I follow what you're talking about clearly at all. On one hand it sounds like you want a sealed volume between your facing drivers that are out of phase... with only one side of this facing the room. Given the availability and cost of good high-excursion drivers well suited to IB use I really don't see the complexity of this to be worthwhile.

If you go totally gung-ho, I think you'd find yourself with a pile of Tumults and more clean bass than you know what to do with. ;) I'm saving my pennies, but I don't know when I'll get there.

Meanwhile, my pair of Dayton 15" IB subs is quite satisfactory in my small room (9'x13' with 7' ceiling). For now.

Hybrid: Consider Tempests over the Daytons IMHO. And, as mentioned, more power than 250W for a quad of drivers.

C
 
Well currently I have a 12" in a 3.3CuFt enclosure and a 80W amp feeding it, and it seems to be OK, however it just physically doesn't go to low....maybe 40Hz before sharp falloff.

So using 4 15", would be like 8 times the radiating area, and then add 4 times the power. I think it should be plenty.

So, since the entire attic is being used as the enclosure, does this mean other rooms in the house my get some bleed through? Or will the large volume simply dissapate the air being moved?

The idea of putting Sonotubes up there sounds interesting. Just have a box with the drivers, then run a sonotube (or several) across the rafters. This way, I could get a relativly large enclosure, but everything would be enclosed (and protected from debris as pointed out).

It looks like a 25 CuFt enclosure on one IB15 (using a 24"x96" sonotube) would still yeild a very low F3.


Heres a question though, if I made a ported enclosure inside the attic, and the driver fired into the listening room, but the port fired into the attic would I loose the extension of a port, or does it matter? Basically does the port have to fire into the same air space as the driver?
 
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