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Old 16th August 2010, 03:17 PM   #11
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Originally Posted by bigjppop View Post
From my VERY limited understanding of the world of subwoofers, it sounds like exact volume is not SUPER important for a sealed design; correct?
No, it's not, but try to get as close as you can, it's never wrong to try to be accurate.

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Originally Posted by bigjppop View Post
Next question, read somewhere else that "for music a Q of about .7 is perfect.". I don't know what Q measures and the other didn't say why a Q of .7 was perfect for music.

Last question, the nuts and bolts of construction. I think I'm planning on using the polyfill stuff but just want to confirm that I'm on the right track.
When calculating the box size in relation to Q, don't forget to account for room gain and the like. That means that if you are aiming for a final Q of say 0.7 you might want to make a box that is somewhere in the 0.6-0.65 range (I've been tol myself) to land around 0.7.

Normally, as far as I've understood, a sealed sub is to be filled 100%, and you can use ordinary glass fiber stuff. I've forgotten the exact products mentioned in Dickason's "Cookbook"

You might also want to consider the option of damping the interior walls of the box.
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Old 19th August 2011, 05:11 AM   #12
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Well I hate to admit it, but life got in the way and both this driver and the amp are still in their boxes in my room waiting for me to get going on this project.

I've finally got my room set up and just want to make sure I'm still tracking with an appropriate design. This sub will be probably a 90% HT sub because my current sub keeps bottoming out in movies. It's a little Hsu sub that only has a 10" driver so there's only so much I can expect. It sounds great for music, but it's coming up short in movies.

Anyway, room size is only about 12x15, I don't need to fill a concert hall with sound, but I don't want my sub to bottom out every time Iron Man takes flight. Sealed still the way to go? The T/S specs are listed at the beginning of this thread. I'm still thinking about 4^3 ft for the box.

Thanks again for all the assistance. I hope to have something to show for it soon.
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Old 19th August 2011, 10:58 AM   #13
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I would suggest getting an EP2000 amp to run the subwoofer, and why not go ported? 8 cubic feet, tuned to 20Hz, with an 8" port, gives you a huge increase in output in the 15-40Hz range, and if its for home theatre, that's perfect

If you bridge the EP2000, it will deliver around 1100 watts, so a HPF at 16Hz would be a good idea.
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Old 19th August 2011, 09:12 PM   #14
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i think you'll be happy with a sealed 4ft^3 box. I'd use an amp with a parametric eq built-in but the one you have will get you on your way. remember, you can always build another box or add ports to the one you are going to build. a 4ft box will tune nice and low as long as you keep one dimension long enough for the ports. I always keep one side at 24" when I build a sealed box for a customer so i can add up to a 21"legnth x 3"dia. port if they want it to go lower.

important: don't go too far with finishes until you are happy, an unfinished box just means you're still in the testing phase
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Old 20th August 2011, 07:32 AM   #15
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Originally Posted by revboden View Post
i think you'll be happy with a sealed 4ft^3 box. I'd use an amp with a parametric eq built-in but the one you have will get you on your way. remember, you can always build another box or add ports to the one you are going to build. a 4ft box will tune nice and low as long as you keep one dimension long enough for the ports. I always keep one side at 24" when I build a sealed box for a customer so i can add up to a 21"legnth x 3"dia. port if they want it to go lower.

important: don't go too far with finishes until you are happy, an unfinished box just means you're still in the testing phase
Very good idea, I hadn't thought of that. I'll make sure one side is at least 24" and definitely leave it unfinished until I'm sure.
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Old 20th August 2011, 09:06 AM   #16
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FYI:

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Old 20th August 2011, 06:58 PM   #17
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A 3" port would result in a extremely fast air velocity, and probably start to compress with more then 70 watts input power, you would need a 6" port minimum, and and 8" port preferable to avoid port compression and noise with a high excursion 15".

If you have the room, build a horn subwoofer, its nearly always going to give you the best output, I would build them, but I still have to get around to learning Horn response.
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Old 20th August 2011, 07:14 PM   #18
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Originally Posted by Homeboydeluxe View Post
A 3" port would result in a extremely fast air velocity, and probably start to compress with more then 70 watts input power, you would need a 6" port minimum, and and 8" port preferable to avoid port compression and noise with a high excursion 15".

If you have the room, build a horn subwoofer, its nearly always going to give you the best output, I would build them, but I still have to get around to learning Horn response.
that would depend on how it's tuned, say you tuned the box to 8hz the max vent velocity at Xmax / 20Hz with two 3"ports would be around 10m/s, very usable. 3" was just an example.

With that driver and high tuning i'd use a slot port.
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Old 21st August 2011, 06:16 PM   #19
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Just curious, any harm in pushing the sealed box to 6^3 ft? That seams like it would add more flexibility should I decide to go ported later.
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Old 21st August 2011, 09:21 PM   #20
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Going to 6^ft will lower the Qtc from .6 to around .5, not a problem if the sub is for HT.

6^ft tuned to 21Hz with a 6" port would be a nice sub indeed, problem is, with 800 watt (the drivers rating) the air port velocity is 32m/s which is too high.

What amp are you using?
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