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Discussion Starter #1
Guys,

I was happily planning my basement. Had a nice little media room. Not a dedicated theatre per se, but a nice room.

Was looking for various speaker/tv/video distribution details, came to this forum.

Bad idea.

I was going to buy a simple integrated sub and put it off near a side wall. Now I want to build my own subs.

Room layout is on this thread: http://www.avsforum.com/forum/15-ge...me-rooms/1949577-dmrfresh-basement-build.html


I'm on the fence about a few things.

1.) Placement. Needs high WAF. Considering a pair of front firing subs flanking fireplace, or side firing maybe 4 feet away from TV wall.

2.) Type. Havent figured out how this might work, but I'd like to integrate the box into the wall. Thinking I can get my volume vertically - maybe something that is 16" wide by 7 feet tall by 6-12" deep? Could run long ports and hide them in wall as well. Again, want to integrate the subs into the room for high WAF.

3.) Number/size. I'm getting old. I don't need bonecrushing bass. I want clear bass, well balanced with the high frequency stuff. Want "clarity" for music. I will be using room for movies as well, but I just want solid reproduction - won't get the "immersive" experience with the non-projector setup (plus no WAF for high volumes - she's also getting old).

4.) Drivers. I'd like to repurpose the drivers from my currently non-functional KSP300s. I think they are 12" drivers? Haven't looked up the type. Would be cool from the reuse factor. If that's not worth it, I can buy drivers.

5.) Prewire. 12Awg to sub locations?

Man, this forum just made my basement more complicated :). As my buddy who's helping out says, "Scope Creep!".

Thanks in advance for your advice!
 

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The beauty of DIY is that you can do anything. Generally people in here will recommend 18" drivers because it is easy to hit reference volumes, but that isn't horribly compatible with your 16"x12"x84" box constraint. It's a little hard to recommend using the 12s you have. You could probably do a sealed enclosures in that volume that would fit two Dayton UM15 drivers, for a total of 4xUM15 hidden in the wall (similar to blazar's setup). A ported enclosure of that size will probably only work for a single UM15, or you could even do a tapped horn if you want to be adventurous.
 

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Lots of options for you here. I agree with Frisco and would suggest a pair of sealed drivers in wall per side. Simpler build and should be plenty of output for your described needs.


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Discussion Starter #5
How did you arrive at requiring 4 subs for the necessary output. Maybe I'm old school but that seems like overkill.

I could widen the box to accommodate larger drivers. Probably keep it to the window width
 

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Because more is always better!
You have the space, but I'm sure sticking with two will make you happy as well.


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You can use the freeware program WinISD to model the sealed and ported sub options, or there are plenty of people here that would probably do it for you. You need to decide what your goals are, and that will guide the decisions and get you to a design. Generally people in here want to be able to produce reference level volume or higher, without significant distortion, and without significant variability in the volume level at the different seating locations. Some want inaudible rumble that is present in many movies, and others want a pancake flat frequency response. Some might just want notariety. You won't get everything for free, and often you'll find that there are compromises. Depending on your goals and the constraints, we can go from there. I recommended 4 sealed subs largely because it would reduce the sound level variability in different seating locations and fit the size constraint that you listed and be something that you could fit right into your wall as you said you desired. But if you provide more information or are open to consider different options, there are definitely plenty of different paths.
 

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Discussion Starter #9
You can use the freeware program WinISD to model the sealed and ported sub options, or there are plenty of people here that would probably do it for you. You need to decide what your goals are, and that will guide the decisions and get you to a design. Generally people in here want to be able to produce reference level volume or higher, without significant distortion, and without significant variability in the volume level at the different seating locations. Some want inaudible rumble that is present in many movies, and others want a pancake flat frequency response. Some might just want notariety. You won't get everything for free, and often you'll find that there are compromises. Depending on your goals and the constraints, we can go from there. I recommended 4 sealed subs largely because it would reduce the sound level variability in different seating locations and fit the size constraint that you listed and be something that you could fit right into your wall as you said you desired. But if you provide more information or are open to consider different options, there are definitely plenty of different paths.
Playing around with WinISD.

9.3 cu ft box (7ft x 6in x 32in)

Seems weird, but with a 3 in port it has a resonance at 21Hz, and shows what seems like would be reasonable performance (to my untrained eye).

I guess I have to play around and pick the right drivers though.

With porting the box, are there any "rules of thumb" that i'm probably missing?
 

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Discussion Starter #10
Found the klipsch driver specs

Suitable for sealed or vented enclosures
120W/240W RMS/peak
Polypropylene cone
Rubber surround
1.5" voice coil
24oz. magnet
Sensitivity: 91dB (W/M)
Impedance: 8ohm
Re: 7.2ohm
Le: 0.91mH
Frequency response: 50Hz~5KHz
Fs: 42Hz
Qts: 0.47
Qes: 0.57
Qms: 3.24
Vas: 122.6 liters
Xmax: 5mm
Overall frame diameter: 12.20"
Required cutout: 10.95"
Mounting depth: 5.04"

Read more: http://www.hometheatershack.com/forums/diy-speakers/61200-my-build-list-s.html#ixzz3VqAStMxF
 

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Discussion Starter #11
Found the klipsch driver specs

Suitable for sealed or vented enclosures
120W/240W RMS/peak
Polypropylene cone
Rubber surround
1.5" voice coil
24oz. magnet
Sensitivity: 91dB (W/M)
Impedance: 8ohm
Re: 7.2ohm
Le: 0.91mH
Frequency response: 50Hz~5KHz
Fs: 42Hz
Qts: 0.47
Qes: 0.57
Qms: 3.24
Vas: 122.6 liters
Xmax: 5mm
Overall frame diameter: 12.20"
Required cutout: 10.95"
Mounting depth: 5.04"

Read more: http://www.hometheatershack.com/forums/diy-speakers/61200-my-build-list-s.html#ixzz3VqAStMxF
Now that i just pasted it in there, I see the low frequency cuts off at 50 Hz....

Is that the kind of thing I could compensate for with gain from a port tuned low?

I guess I'll throw the parameters into WinISD and see what happens.
 

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Discussion Starter #12
Now that i just pasted it in there, I see the low frequency cuts off at 50 Hz....

Is that the kind of thing I could compensate for with gain from a port tuned low?

I guess I'll throw the parameters into WinISD and see what happens.
And I'm guessing from my results in the model, this driver is never going to get very low.

Ok, so where do I even begin to look for drivers?
 

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That Klipsch driver isn't particularly special, and doesn't have enough xmax for real low end. Plus with the higher Fs, it isn't designed to. Common subs generally don't go very low and loud; they tend to have a ton of output in the ballpark of 50 Hz, aren't very balanced sounding, and can't go very low at all. Most of the recommended DIY theater subs are tuned to the ballpark of 20 Hz to support rumbly movie sound effects.

Generally, recommendations people make for sub builds work back from the primary constraints: #1 Budget. #2 Size of the subs. #3 The room. You've got a relatively open room, so you want to get as much output as you can within your budget and space.

Is 7' x 6" x 32" the internal or external dimensions of your proposed box? Note that 6" deep isn't a lot of room for a sub driver; you could bump out that section of the box if you want to keep the depth limited overall. 3/4" plywood or MDF are most commonly used, and it's also common to double the thickness of the baffle to recess the driver into it. So internal dimensions end up being 1.5" shorter, 1.5" narrower, and 2.25" less deep than the external. You also have to subtract out volume the drivers them selves occupy, for bracing internal to the box, and for the port. Ballpark, you could say that net internal volume is something like 60% of gross external volume. So a 7' x 6" x 32" external box gives you 5.6 cubic feet net internal, roughly.

For designing that into a ported sub, the process is basically to pick a driver, plug it into a box, and select a tuning frequency. Then plug in the amount of power you can give it. Then go look at the excursion graph, and see where it blows through xmax. Set a High Pass Filter to limit excursion. Then go look at the port air velocity graph. Generally you want that under 20 m/s at its peak so you don't hear the port chuffing. Increase the size (or number) of ports until that number is under control. Keep an eye on the first port resonance, you generally want that to be over 160Hz. The frequency of that resonance gets lower as the port gets longer, and the port gets longer as it gets wider/taller. So the design process is a balancing act.

The MartySub FAQ thread is a good read since it has a lot of general purpose information on building subs. http://www.avsforum.com/forum/155-diy-speakers-subs/1648673-martysub-faq.html Given the approximate size of the box you have, you're in the same size and performance range as the Martycube.

As for where to look at drivers, there are tons out there. The bang-for-your-buck favorites are the Infinity 1260w and 1262w, JBL GTO1514 and GTO1514D, and Stereo Integrity HT18. Look at the Dayton Ultimax and RSS models as well. There are higher-end options as well, if your budget allows.
 

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Discussion Starter #14
Thanks, very informative. I'll be playing with possible configurations, and I'll post something when i think I've got an idea i like.
 

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Discussion Starter #15
Anyone see any issue with pre-wiring sub locations with 14 gauge NM instead of 12 gauge speaker wire?

Neither type is impedance controlled, so I figure the NM is really overkill - I just have lot of leftovers.
 

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Discussion Starter #16
Has anyone tried to re-use a pre-built cabinet for housing their sub by replacing the doors with a properly sized baffle? Port holes could be drilled into the side.

Wondering if I could take a pair of 24" cabinets, and repurpose one into a sub enclosure, enabling me to have an integrated sub/cabinet look?

Thoughts?
 

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On the fence: DIY sub for "media room"

I'd imagine the sides and back are 1/4" ply or particle board or something, so you'd need to reinforce with some 1/2" ply or MDF, add bracing, and thoroughly caulk it so it's airtight. But no reason you couldn't do that. You might even be able to keep the doors as the outer layer of a double baffle.
 

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Discussion Starter #18 (Edited)
I think I'm leaning towards a single dayton 15 ultimax in a sealed cabinet (~24x24x34 outside dim).

I'll have the cabinet custom built with the other wall cabinets, for an integrated look.

Probably setup the sub to be downfiring, with 5" legs to raise the cabinet.

Then get them stained/veneered to match the rosewood OMD 15s.

Black granite tops to round it out.

Probably get an iNuke 3k to drive them.

Any advice before I get too far down this path?
 

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Discussion Starter #20
Been awhile. I got lazy and threw the pre built box with ultimax 12 into my cab. looks good, but I need to make some measurements for performance.





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