Closet sub

[azagthoth]

I am in the process of building a theater room in our basement. I have a closet that will be ending up behind a screen wall which I figure I could turn into a large subwoofer enclosure. I am not sure what exactly to build into the space I am just looking for some ideas. The closet itself has a volume of around 1600 liters and the theater is approximately 24'x13'x8'. For the subwoofer budget I am aiming to be under $2k for the amplifier, drivers and eq.

Michael

[ThomasW]

The closet must not be used for storage and must be made air tight. A pair of 15" or 18"s would work fine.

[azagthoth]

I was not planning to store anything in the closet it will be completely converted into a subwoofer.

Would it be recommended to build all sides of the enclosure inside the closet with wood overtop of the walls and bracing inbetween or could I just use the finished drywall for the inside sides of the enclosure and build the baffle over the opening (ensuring everything was airtight) ?

I guess I am trying to decide whether to really build the sub into the structure of the house or just build the sub as a seperate cabinet that takes up the entire closet space.

Michael

[ThomasW]

How about posting a drawing of the floorplan?

[azagthoth]

Here is a floorplan of the room. Although I labelled the one part as a screen wall this is going to be a solid wall not an acoustically transparent wall. So I was either building an opening for the drivers or build the enclosure out of the closet and into the wall.



Larger Version

[ThomasW]

Is the 'closet' an alcove? If not what's on either side?

[azagthoth]

Sorry I forgot to mention this is in a basement. On the other side of the drywall of the closet is fiberglass insulation and then concrete.

[ThomasW]

There's a 48" X24" 'notch' in a concrete wall?

My question was what's on 'either' side (left/right, aka the lateral sides) of closet

[azagthoth]

I added some more information to the floorplan. Does this answer your question ?

[ThomasW]

Yep that answers the question.

Assuming brown = studs.

Don't make it into a closet meaning no sheet rock on the sides or back of niche'.

Extend the stud wall across the front of the niche.

Slap (glue and screw) a couple layers of 3/4" OSB on the studs of only the front wall, leave the sides and back open to the concrete. Prior to closing off the front wall stiffen it by putting 2"X4" from the front to the back of the 'box'. And line the 'box' with 6"-8" thick regular old pink fiberglass insulation.

When you're ready to fire things up we'll see what the best deal is for drivers.

[azagthoth]

The three walls that make up the closet are already built. I guess I should have mentioned that this is an already developed space we are changing. I can rip out the drywall, studs and insulation that is already in place and go right back to the concrete if it would be better for performance. However if the sub could be build into the existing structure without it being too detrimental to performance that would be my preference.

[azagthoth]

Here is what it looks like right now. That shelf is going to be removed.

[ThomasW]

I would remove the drywall (leave the studs).

Then extend the existing wall across the opening with studs (top/and floor plate).

Tie the front wall (baffle) to the rear wall with 2"X4"s, this is to cut down on the baffle flexing.

Line the enclosure with insulation as I posted above.

Make a baffle with 2 or more layers of 3/4" OSB. With liquid nails on the studs, screw on one layer. Use a mastic to coat the entire first layer of OSB, then screw on the second layer, then repeat....

If you precut the driver holes before attaching the OSB to the studs life is easier. If you go for a thick baffle, the inner holes should be larger in diameter than the outer holes. This avoids having the wood 'mask' the rearwave of the woofer.

[Dennis H]

If you remove the drywall, you'll have to seal it somehow so the backwave can't get behind the drywall you leave on the front wall. Otherwise that whole wall will act as a radiator. It might be easier to just leave the drywall.

[ThomasW]

It might be easier to just leave the drywall.

Easier yes, but.....that will make the space smaller and flexible (lossey) in comparison to having 3 sides of the enclosure be the concrete foundation.

I don't see sealing the sides as a big deal. Score to the shape of the concrete the 2"X4"s, then seal any gaps. That's why things like Great Stuff foam and caulk were invented....

[azagthoth]

Thank you for the ideas. I have another wall to demolish in the basement this week anyways. Removing the drywall won't be too bad. I will post some pictures and a plan for the enclosure later this week once the drywall and carpet are out.

[azagthoth]

2 weeks later I have managed to remove the drywall and the carpet. I also chose to remove the studs as well because some of them had a gap of an inch or more to the concrete. I think it would be easier to build something new to get a better seal. Here is what it looks like now:



The following are the plans for the enclosure so far. Instead of making the baffle flush with the concrete opening I decided to extend it out about 8 inches. This will allow me to integrate the front of the sub with my screen wall better. The total dimensions are 56" wide, 33" deep, and 90" tall.







I still have some questions:
1) The top of the closet space is not concrete, above it is standard wood floor. Would it make sense to make a concrete top for the enclosure or should I just layer wood the same as the baffle for the top ?
2) Does anyone have suggestions to improve the enclosure ? This is my first attempt at building a sub.
3) Do I need to reinstall a vapour barrier for the inside of the enclosure ? It is pretty dry here.

[ThomasW]

There's simply no reason to have stiffening bracing when there are 4 concrete surfaces.

The only things that need any bracing are the top and front baffle.

If the sides of the baffle overlap the concrete a couple of inches, you can glue the baffle directly to the concrete, using liquid nails or polyurethane caulk.

Glue a few of 2"X4" from the baffle directly to the rear wall concrete.

[azagthoth]

Does this look more reasonable ? I guess the other one was pretty excessive. This is easier to build anyways.

[ThomasW]

Yep looks fine.... :T

[Mazeroth]

Should turn out to be a great sub.

I'm always amazed at how well the members on speaker building sites model their plans. It's like you're all CAD professionals or something!

[azagthoth]

Thank you for your comments. I have found it a lot easier to create designs quickly since I started using SketchUp.

I was thinking I should order my other components soon so that they can arrive closer to the time the enclosure is finished. I am looking for some suggestions. So far I was thinking of ordering the following:

2 SoundSplinter RL-p18
1 Behringer Europower EP2500
1 Behringer Feedback Destroyer DSP1124P

I looked at some of the TCSounds stuff (Also 18s TC-5200, LMS-5400) but I am not sure if I would gain much from spending more than twice as much on drivers. I also looked at the Aura sound drivers but again they seem very expensive. What else is out there for 18s ?

[PoorboyMike]

The Q series from Fi-Car Audio is a popular option. Fi will also be carrying the new line of AscendantAudio stuff, which should be out any time now.

Another option is Mach5 Audio. Their new IXL driver seems to be a good buy.

[azagthoth]

The mach5 looks good for the price. I also might save a lot on shipping that way being located in Canada.

[Hdale85]

I'm sure the RL-P18 would outperform the IXL but by how much I couldn't say if it would be worth the extra cost.

[Jack Gilvey]

'Nother closet-subber here. It'd be even better to have the drivers opposed in a recessed manifold. Might not be a big deal with all that bracing.
Here's how mine are recessed into my closet:

[azagthoth]

I am guessing the purpose of the recessed manifold is to have smaller and more rigid baffles ? Does it have other advantages ?

[PoorboyMike]

I am guessing the purpose of the recessed manifold is to have smaller and more rigid baffles ? Does it have other advantages ?

Yes. With the drivers facing each other it cancels out most of the mechanical forces. Your closet will be braced very good though, so I'm not sure how necessary it would be.

[azagthoth]

I started working on the closet this weekend. I spent some time saturday taking an angle grinder to the concrete to get rid of the bumps where the top of the box will be going. So far I only built the frame for the top since the stores near me won't cut panels on the weekend because they are too busy. Not much progress but it's a start. I am going to get the rest of the wood tomorrow after work.



I decided to stay with my original design instead of changing to the recessed manifold.

I am closer to ordering things but I still have some things I need to figure out. How are people running their amps ? I will be sending the .1 channel from my reciever to the amp but I am trying to decide if I should run the amp bridged or put a driver on each channel. After looking at the options I am still planning to go with the original equipment I posted (2 SS RL-p18, EP2500, and Feedback Destroyer) I just need to figure configuration of voice coils to get.

[Hdale85]

Well If the EP2500 will handle 2ohms I would bridge it :B Because I'm sure those drivers are going to take all the power you can possibly dish at them.

[ThomasW]

I'd get the dual 2 ohm drivers, wire the VC's on each drivers in series for a 4 ohm load on each channel

[azagthoth]

Everything I ordered arrived this week. I went with the EP2500, Feedback Destroyer and 2 Soundsplinter RL-p18d2.



The actual enclosure construction has been going well but slowly.



This is the top piece of the sub, turned out a bit heavier than expected and it was real fun getting it into position 7 feet off the ground. :roll:





Tonight I am working on building the frame for the front of the sub.

[azagthoth]

I finished the frame for the sub today and started sealing some of the gaps with great stuff.



So that leaves more sealing, adding insulation, cutting & attaching the panels, and mounting the subs.

One point I am still trying to figure out is the best way to attach the insulation to the sides of the enclosure. I was planning to just use the pink stuff. One idea I had was to use chicken wire and staple it to the wood in the corners of the enclosure. Not sure how well that will work. I would like to hear any suggestions people have.

[Gir]

Using spray glue should hold them up pretty well. If you have any scrap wood just nail two or three pieces across it to make sure (with spray glue to hold it on that side as well) it will never fall over.

Looking good so far! Can't wait to see it finished!

[ThomasW]

Use the professional liquid nails since it's designed to handle potentially damp surfaces like concrete. A thin bead zig-zagged across the back should do the job

[azagthoth]

I have not seen liquid nails on the shelves of the stores near me. They only carry lepage stuff. They have something called No More Nails, is this the same thing ? The other option is to use a Polyurethane Construction Adhesive which might better since it actually says it is water proof.

[Gir]

I know that spray adhesive works great for anything fabic, and acording thistothat.com, fabric to ceramic you should use 3m 77 (spray adhesive). I figured ceramic is pretty close to cement, no? Either solution would work I guess.

BTW, a polyurethane glue should work pretty well I suspect. And as for liquid nails, as far as wood glue goes Elmer's glue is just as good if not better.

[ThomasW]

I have not seen liquid nails on the shelves of the stores near me. They only carry lepage stuff. They have something called No More Nails, is this the same thing ? The other option is to use a Polyurethane Construction Adhesive which might better since it actually says it is water proof.

Either of those is fine.

I know that spray adhesive works great for anything fabic, and acording thistothat.com, fabric to ceramic you should use 3m 77 (spray adhesive). I figured ceramic is pretty close to cement, no? Either solution would work I guess.

BTW, a polyurethane glue should work pretty well I suspect. And as for liquid nails, as far as wood glue goes Elmer's glue is just as good if not better.

We're gluing to concrete here, so it's ability to wick moisture/dampness must be taken into consideration. Also one much factor in the irregularities in the concrete surface.

[Gir]

Also one much factor in the irregularities in the concrete surface.

Would that make the polyurethane a prime candidate then since it expands?

[ThomasW]

IMO, polyurethane glue is not a candidate for this application, since the foam generated when it fills a crack has no strength.

Polyurethane caulk is a completely different animal and adheres to almost anything, which is why it's used to fill cracks and expansion joints in concrete.

[Gir]

IMO, polyurethane glue is not a candidate for this application, since the foam generated when it fills a crack has no strength.

Polyurethane caulk is a completely different animal and adheres to almost anything, which is why it's used to fill cracks and expansion joins in concrete.

Thanks for the tip, I'll remember that!

[azagthoth]

I have been working on my sub more and I got it to the point I am about to mount the drivers.





I was testing out the subs before I mounted them. I have them with the voice coils in series and each driver on a seperate channel. Currently I am not using the feedback destroyer since the room isn't done. I just have them hooked up to my reciever with a cleanbox before the ep2500. I was just wondering how typically people set the volume on their components. In the end I will measure it to get it right but do most people run the amp wide open at max volume and then use the reciever to match the level or do they use the amp to set the volume and leave the reciever neutral ? I seem to be getting a lot of buzzing when there is no signal if I turn the amp past 1/3 of the way up.

[WillyD]

I seem to be getting a lot of buzzing when there is no signal if I turn the amp past 1/3 of the way up.

Could be ground loop. Might suggest picking up a cheater plug (3 to 2 prong plug adapter) at Home Depot or wherever. Can be had for very cheap.

[azagthoth]

Since it is close by I tried plugging the amp directly into the panel plug which is on its own breaker and the hum seems to be greatly reduced. With the sub right beside the panel I guess I could just add another circuit for it.

[WillyD]

Thats a good idea.