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Building my first 4th order bandpass box.


d-nice88

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Ok im doing this just to try n see if I can do one. Im going to be using some cheap 8" subs. Maybe some planet audio 8's. Can I do this and what is the ideal fs number and qts number to look for ? Any help would be great guys just wanna say again im just trying to see if I can do one not trying to win a comp or anything I just got some extra wood on my hands since I never got another design for my fi bl subs.

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For a 4th order bandpass you are going to want subs with a lower Fs and higher QTS (>.5). Fortunately this is what you get with a lot of cheaper subs. If you are going to use 8"s I'd suggest using more than one, otherwise the chamber volumes can be so small it makes things difficult. If you want to use just one sub, get a cheap 12".

Do you want to try to make the box sound good, or do you just want to see how loud you can get?

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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OK, keep in mind that with bandpass boxes, everything is a tradeoff. If you want a box that sounds decent, with a wide frequency range and smooth response, its going to cost you efficiency. A ported box will be more efficient. To get more efficient than a ported box, you are going to have to give up a lot of bandwidth.

If you want a suggestion for a sub, an Infinity 1260W or 1262W will work well. They are inexpensive, don't suck, and will work decently in a 4th order bandpass design.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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For that sub I'd recommend 1.35 cf sealed, 1.25 cf ported @ 45 Hz. That should give you a box that produces pretty smooth even bass, with a slightly rising low end response, depending on how much cabin gain you get.

For ports you could use three 3" ports about 20" long, or two 4" ports about 24" long. These are assuming 500 watts of input power. I like to use round ports for bandpass boxes if I can, since they are easier to adjust in length. I recommend starting with your ports long, trying it out, and then shortening the ports to raise the tuning until it sound best to you. Set your subsonic filter to 24 hz to protect the sub.

I also recommend having the motor in the ported section of the box, if possible, so it gets better cooling and you can smell the coil if you start to push it too hard.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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