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Old 02-24-2011, 05:24 AM   #1
Cudda_Kine

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Lowest tuning for a subwoofer box.

Wanted to do something a little funny/crazy. Either 10" subwoofer for 10hz box. 12" for a 12hz. Or 15" for a 15hz box. I'm not sure if it will go that low but I have the room for such a large box. If anything. Would a Double 10" box work with 20hz tuning? Just trying to get a box at least under 30hz minimum. And yes, this is for real. Please let me know what exactly will it sound like.
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Old 02-24-2011, 05:29 AM   #2
Cudda_Kine

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Already found the answer.
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Old 02-24-2011, 07:59 AM   #3
MysteryMethod

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Pete from PWK Enclosures did something like this with a 10 Alpine Type R.

It's possible to tune an enclosure very low but it will usually cause the port to absolutely huge and usually not practical. Unless you enjoy listening to subsonic test tones, tuning any lower than 25hz seems slightly pointless. Most subs, regardless of enclosure design, will start to roll off below 25hz despite the tuning. It's possible to combat these effects, but it's probably not worth the effort.
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Old 02-24-2011, 09:14 AM   #4
Cudda_Kine

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Thanks man. The reason for all this is that I used this box with a 15" Type-R Subwoofer using a faceplate on it.

http://i5.photobucket.com/albums/y15...e/IMG_0466.jpg

This box is built for a 21" subwoofer @ 33hz. What was the tuning when I put the 15" subwoofer in it using the 15" faceplate? Less than 30hz right?

I want a Giant box made for either a Single 10", 12", or 15". No more faceplates. How does "12" Subwoofer box @ 24hz" sound? That would be a little more reasonable right?
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Old 02-24-2011, 01:26 PM   #5
Jimi77

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Quote:
Originally Posted by Cudda_Kine View Post
Thanks man. The reason for all this is that I used this box with a 15" Type-R Subwoofer using a faceplate on it.

http://i5.photobucket.com/albums/y15...e/IMG_0466.jpg

This box is built for a 21" subwoofer @ 33hz. What was the tuning when I put the 15" subwoofer in it using the 15" faceplate? Less than 30hz right?

I want a Giant box made for either a Single 10", 12", or 15". No more faceplates. How does "12" Subwoofer box @ 24hz" sound? That would be a little more reasonable right?
The tuning doesn't really change when you swap subs.

A 2 cuft slot ported box (2.5 x 14" slot") would require a 114 inch long port. Realistically, you would need use a passive radiator rather than a port. Not only that but you'll need a sub with an FS close to 20hz. Actually you'll probably need 2 PRs with that low tuning frequency. Something like this kit.

http://creativesound.ca/pdf/Quartet1...woofer_Kit.pdf
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Old 04-16-2011, 10:16 PM   #6
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PR's are a good idea if you are tight on space. You might pick ones that allow you to add additional mass to them - adding mass lowers the resonant frequency of the radiators themselves, and therefore the low frequency extension.

But remember, you have to deal with physics. The Iron Law states that the following three things are mutually exclusive:
1) small enclosure size
2) high efficiency
3) low frequency extension

Your subwoofer affects the low frequency response as well, even though they work as a system... you might argue (I would) that box trumps subwoofer in terms of overall performance.

You'll want to use a subwoofer with a low Fs.
If your subwoofer's Fs isn't low enough, you could try to make the cone heavier by painting or otherwise coating it, but you wouldn't want to go too crazy so as not to overstress the suspension or increase excursion too much. You might notice when you are modeling the PR's, how adding mass increases excursion.

Typically, for these goals, you'd want the largest diameter sub you can house... you'll note as a generalization that 15's have lower Fs than 10's, because of the larger moving mass inherent in the larger cones, all else being the same for like-model subs.

And with PR's, you can get away with a pretty relatively small enclosure, still preserving a decent frequency response.

In fact, depending on your goals here, you can create a pretty critically small PR box, using the PR to extend the response very low, and the small enclosure creating a hump somewhere around your LP Xover point, the result can be a somewhat gentle downward slope from there...
That's good, in a car, because of cabin gain that'll boost your bass response in our closed spaces by about 6db/octave - so in terms of "actual, in-car frequency response" it can net out flat.

I am actually in the process of building a very tiny enclosure that'll essentially fit on my rear deck (without obstructing my view - about 4" high, 'glassed and carpeted) to house two 8" subs and two high-excursion flat panel 10" PR's.

If you go the PR route, note that as a general rule of thumb, it works out better if you go up at least a standard size for your PR's.

Don't discount the simple option though-
An 'as large as you can afford' sealed box with a sub that has a very low Fs. Remember, you have cabin gain working for you to get that subsonic frequency stuff up there for you. Both vented boxes AND passive radiator boxes will absolutely kill off your low frequency response below your vent or PR tuning frequency. For that matter, you don't even want to think about trying to play notes below your tuning frequency, or you'll blow your sub by virtue of overexcursion without a fraction of it's rated power applied.

Keep us in the loop on what you decide.
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