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Discussion Starter #1
Hello,
I am planning our new subwoofer for the new house. I have not decided on a LLT or infinite baffle but this thread is limited to the manifold design. I also have not decided on the drivers. I may either use the two Titanic 12's in my closet or purchase 4-8 Mach 5 IXL 18.4's. It just depends on what manifold design is feasible. Our living room only has a small section of wall linking it to the attic. This wall is triangle shaped due to the vaulted ceiling. The width is about 16 feet with a height of about 3.5 feet. Add to this that the room is an add on with the original roof being perpendicular to the living room this makes it a very tight fit. The only A/C vent is also on this wall. We also do not want to cut the paneling without making it look original.

Therefore I plan to combine the two existing ducts to one one side and install a larger register. On the other side I will install another matching register with a manifold behind it. Everything seems viable until the port comes into the design.

Option 1:
Port extends from the "box" through the back wall of the manifold and to the surface of the wall. I do not see how I can make the opening large enough to give the drivers enough free air and house the port tube. What is the standard thinking of how much breathing room to give the front of the drivers without tuning the front wave like a bandpass box?

Option 2:
Like above but have the port opening terminate on the back wall of the manifold. Will having the port opening share the manifold give a problem with tuning?

Option 3:
I may need to build wider more shallow manifold. To do this I would need to have the A/C duct terminate on the back wall of the manifold. Would placing such a significant "pressure leak" inside the manifold lower the output?

Thanks for any help.
Zach
 

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Your pic isn't showing up, and I'm having a bit of trouble visualizing your layout and your proposed ideas; could you post a sketch of what you're thinking?
 

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Mike, do I just not know how to click a link, or is there something wrong with the pic link still that just takes you to photobucket??? :huh:
 

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I give up; it's probably the computer I'm on. You posted the picture anyways, thanks! I'm interested to see which option gottavtr wants to go with.

It seems like not messing with ports would be easier and to just go with IB, but I am not well versed in IB requirements.
 

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Just a blunt reply: But what do you mean by port? The only one of your option's i'd worry about is #3 but that could be cured with rubberized undercoating or some other sound deadener and sealing it off but that can get spendy$$$. FI also makes some awesome IB's.:T
 

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Discussion Starter #11

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Discussion Starter #15
I have been up there a couple of times and 70-90 cubic feet is a good estimate for the space outside the original roof and encased in the new roof. I would of course do measuring to get that more accurate. The duct work is currently a flexible soft duct so I would not worry about the rattling. I am more concerned about having the duct so close as to loose output into it. If that makes sense.
Zach
 

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Mike, for Option 1 and 2, (well, for all three) do you need to make sure the manifold opening area is > or = to the Sd of all the drivers?
 

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It seems with any of the three options you would be losing output to the ventilation unless it was routed through a rigid, inert conduit and sealed off from the enclosure space. The drivers would be pressurizing the space, and gottavtr noted he was using flexible soft ducting, which would easily deflect even more than regular ducting.

IMO the best thing to do would be to isolate the ducting (it sounds like the space isn't very big, so it shouldn't be very difficult) inside the enclosure using MDF or whatever to create a protective "shell" around the ductwork.

What about something like this to solve the porting issue:
Capture.PNG
 

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Now that I see your pics I understand what you mean by Port and it looks to be quite too small but should be an easy cure. As far as your duct goes if you could isolate it would probly give you more output from the subs.:T
 
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