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I found this forum after searching for a good source of information on an unusual DIY subwoofer I want to build. I have read many of the threads on the subject here and ended up with more questions than answers it seems.

The last time I built a sub it was 2 x 18" and sat above the ceiling in my home theater, in 1992. Looking back and comparing information available then and now, there certainly are more variables to deal with now.

I have some photos of the environment, measurements and other specs below.

This sub will go in my multi-purpose shop, that's mostly used to build things out of wood, but is also used pretty frequently for large gatherings of people that share in the Star Wars fan community, in which I'm very involved.

I want the sub to reinforce the five-channel audio system that with rummaged speakers consisting of two ancient Klipsch Cornwalls as main speakers, and three other Triad speakers. The Klipsch actually have a lot of bass but it's a big room as well, and I don't generally drive them too hard for fear of self destruction.

I only want it for movie sound reinforcement. Explosions and such, need to be felt, and they really aren't now.

Here is an overall photo of the shop.



The main shop is a rectangle 29' x 33'-9" with a 10' drywall lay-in drop ceiling, above which it's another 3' to the bottom of the 2nd story floor. There is another section of the shop that joins it that's 20' x 30'. (think of it as two overlapping rectangles). It's not important to provide sound in the adjoining room.

Ideally, I want to install the sub in an unusual place. Inside the support for the saw in this photo below. This has the benefit of already being built out of 2 layers of 3/4" MDO plywood on the sides and top and not occupying floor space with another thing to keep clean. It would have is 27.375" on the sides of the triangle and internal volume of 4.27 cubic ft to work with. It could be smaller of course, but bigger would be a problem.



I have an extra NAD 2400 THX Amp I want to use to drive it. I believe it's 200 watts bridged and requires an 8 ohm load.

I don't have a preference for the design type, though I do want the most bang for the buck. I'd like to keep the driver cost in the $200-300 range.

I can pretty much build any kind of enclosure in the shop and if this doesn't make any sense to do it in the saw support, I can build a traditional free-standing cabinet.

Just as a point of reference, the last time I built subs it was in my first home theater in 1992. I put two 18s in a large cabinet above the room and fired down into it, and two 12s in the platform under the two main seats.





Any help would be terrific. Compared to 1992, there are many more choices and I would really like to do it right the first time.
 

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You are asking a lot. You want explosions and such to be felt, in a 29' x 33' room that's connected to another 20' x 30' room, with a $200-300 sub powered by 200 watt 8 ohm load. Your options are up the budget or lower your expectations. The best bang for the buck sub out there is a Mach 5 Audio MJ-18M 18" sub. It costs $155 shipped and works in a 10 cu.ft. box tuned to 18 hz. It needs 500 watts at a 4 ohm load to perform.
 

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I agree, Thats a tall order for your budget. Thats a huge space to fill with a small sub. Your going to need to ideally place more then one sub in that space to even make the bass noticeable particularly the lower frequencies below 30Hz.
 

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Discussion Starter #8
Thanks to everybody for the quick feedback.

This helps a lot already.

I see I need to probably change my expectations a bit for performance, and it also seems like I might need to plan on two of these and forget the space I had wanted to use.

I do have two of these amps spare, though I am pretty sure they need an 8 ohm load.

I'd like to use the space above the ceiling, but it's not really free space, in that 12" is for all the mechanicals, like the dust collection, and 24" is for the trusses, which are on 16" centers. Possibly I could make another column or pair of columns that would mimic the ones that go around the steel structural columns. Those could be 10 cubic ft each.
 

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Why not? And it's only like 10, 000.
A few of us have dedicated theatre rooms generally you need one good sub for approximately every 3000 cubic ft of room you have.
I'd like to use the space above the ceiling, but it's not really free space, in that 12" is for all the mechanicals, like the dust collection, and 24" is for the trusses, which are on 16" centers. Possibly I could make another column or pair of columns that would mimic the ones that go around the steel structural columns. Those could be 10 cubic ft each.
Have you given any thought to using sonal tubes for sub enclosures as they use a much smaller footprint.
 

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Well you can start with here I would also expect someone to chime in soon the give you better direction. Sono tubes are really good subs as they are inherently solid and easy to build.
 

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Well you can start with here I would also expect someone to chime in soon the give you better direction. Sono tubes are really good subs as they are inherently solid and easy to build.
Link didn't work so I just searched for sono tubes and read a number of the threads. I'd heard of them but never read anything about them. I really like the idea though. I think even just leaving the tube painted would be great for the shop. Can't really have a traditional cover as it would just become a dust catcher.

What I didn't see was where to go to make actual calculations. Moving the budget up to build two of them as big as possible using my existing two amp becomes the new goal I think. As long as I don't have to buy new amps, the cost will stay in line with what I spend on the project.
 

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Sell the NAD and buy a Behringer EP2500 pro audio amp to run the subs. That would solve the biggest problem.........lack of power.
 

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I must say that I am jealous of your shop! I played around with the idea of a sonosub myself and for the size fo your shop it would probably be ideal! And they look good!
 

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Discussion Starter #20
I must say that I am jealous of your shop! I played around with the idea of a sonosub myself and for the size fo your shop it would probably be ideal! And they look good!
Thanks. It has been fun to build.

Judging by your avatar, you may recognize this stack of parts for an upcoming project.





I am definitely interested in the Sono subs. I think they are perfect for the shop. Have been reading an researching for my next set of questions that should lead to the project.
 
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