New guy installation question
Nov 8, 2016 17:27:49 GMT -7
Post by deudemann on Nov 8, 2016 17:27:49 GMT -7
Hello all, long time reader, first time poster (and IB builder). I have a 15'x20' theater room with a vaulted ceiling and dormer windows. Due to the way the interior was finished, I have two fully enclosed (drywalled) areas in the front of the theater room, one on the left wall, and one on the right wall (symmetric) that I want to use for an IB setup. I have some questions at the bottom (after all of the background info below).
Both of the enclosed spaces are have the following characteristics:
4 feet in length
2 feet in depth
5 feet in height
Total volume is 40 cu ft.
The driver has a Vas of ~7.5 cu ft.
www.parts-express.com/dayton-audio-um18-22-18-ultimax-dvc-subwoofer-2-ohms-per-coil--295-518
Two of the walls (4 foot and 2 foot) are external and are insulated (exposed)
The 'ceiling' is insulated (exposed)
The floor is OSB flooring on top of composite wood I-beams, the ones typically used in home construction.
The 2"x4" wall studs are no farther apart than 16". Most are closer together.
I have run several 2x4 vertical braces between the studs (screwed in), and attached them to the drywall with construction adhesive. The idea was to reduce the area of unsupported drywall.
I want to put a single Dayton UM18-22, baffle mounted, on the 4' length wall (5' high), near the floor.
I am going to mount the speaker on a thick baffle of plywood/MDF screwed into the studs.
When I hit the baffle wall hard with my fist, I hear a drum response at (guessing) at around 100-200 Hz. So I am going to brace the wall. The studs in the region of the speaker baffle will be braced with a horizontal 2"x12" board, tied back to another 2"x12" board on the opposite wall (two feet away) with horizontal 2"x4" boards.
I am not going to go crazy with power, so I will run each with about 300-400 watts RMS. There will be two drivers, one on each wall, baffle mounted, facing inward toward the centerline of the room. I am going for SQ over SPL.
I have run sealed box simulations in WinISD looking at the differences in response, speaker excursion, SPL, etc. comparing a 40 cu ft enclosure to a 7 ft standard sealed enclosure (which I could build two of, and have in the room). They are pretty close, and I can live with either configuration. But I prefer the IB.
I know using opposed speakers is better, but even though I know they are a good value, these speakers are not cheap by my budget. So buying two more (four total) drivers, just for cancellation in a manifold, that I do not really need to reach my desired SPL, is not really what I want to do unless I absolutely have to.
OK, now the questions:
1. I want to do the IB instead of the sealed sub. But, I want to get a general idea if the space and bracing described above will be sufficient for the driver I am using (I already have both). If it is not, I may have to abandon the IB and build the sealed instead.
2. I saw a previous post where someone suggested filling the IB space with stacked pieces of insulation, floor to ceiling. I suppose the intent is to act like a bass trap for the back wave of the speaker. Would this be a good idea in this application as well? I can go wall to wall, floor to ceiling, but only have the space to go one batten deep.
3. If I can raise the 1st mode response of the wall, using the bracing described above, to say one octave over my crossover frequency, will I be OK? I don't expect to cross the IBs over much higher than 100-150 Hz. The main speakers are Def Tech BP6 towers that can go that low without too much trouble.
Thanks in advance for the help.
Both of the enclosed spaces are have the following characteristics:
4 feet in length
2 feet in depth
5 feet in height
Total volume is 40 cu ft.
The driver has a Vas of ~7.5 cu ft.
www.parts-express.com/dayton-audio-um18-22-18-ultimax-dvc-subwoofer-2-ohms-per-coil--295-518
Two of the walls (4 foot and 2 foot) are external and are insulated (exposed)
The 'ceiling' is insulated (exposed)
The floor is OSB flooring on top of composite wood I-beams, the ones typically used in home construction.
The 2"x4" wall studs are no farther apart than 16". Most are closer together.
I have run several 2x4 vertical braces between the studs (screwed in), and attached them to the drywall with construction adhesive. The idea was to reduce the area of unsupported drywall.
I want to put a single Dayton UM18-22, baffle mounted, on the 4' length wall (5' high), near the floor.
I am going to mount the speaker on a thick baffle of plywood/MDF screwed into the studs.
When I hit the baffle wall hard with my fist, I hear a drum response at (guessing) at around 100-200 Hz. So I am going to brace the wall. The studs in the region of the speaker baffle will be braced with a horizontal 2"x12" board, tied back to another 2"x12" board on the opposite wall (two feet away) with horizontal 2"x4" boards.
I am not going to go crazy with power, so I will run each with about 300-400 watts RMS. There will be two drivers, one on each wall, baffle mounted, facing inward toward the centerline of the room. I am going for SQ over SPL.
I have run sealed box simulations in WinISD looking at the differences in response, speaker excursion, SPL, etc. comparing a 40 cu ft enclosure to a 7 ft standard sealed enclosure (which I could build two of, and have in the room). They are pretty close, and I can live with either configuration. But I prefer the IB.
I know using opposed speakers is better, but even though I know they are a good value, these speakers are not cheap by my budget. So buying two more (four total) drivers, just for cancellation in a manifold, that I do not really need to reach my desired SPL, is not really what I want to do unless I absolutely have to.
OK, now the questions:
1. I want to do the IB instead of the sealed sub. But, I want to get a general idea if the space and bracing described above will be sufficient for the driver I am using (I already have both). If it is not, I may have to abandon the IB and build the sealed instead.
2. I saw a previous post where someone suggested filling the IB space with stacked pieces of insulation, floor to ceiling. I suppose the intent is to act like a bass trap for the back wave of the speaker. Would this be a good idea in this application as well? I can go wall to wall, floor to ceiling, but only have the space to go one batten deep.
3. If I can raise the 1st mode response of the wall, using the bracing described above, to say one octave over my crossover frequency, will I be OK? I don't expect to cross the IBs over much higher than 100-150 Hz. The main speakers are Def Tech BP6 towers that can go that low without too much trouble.
Thanks in advance for the help.