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Old 6th May 2010, 06:29 AM   #1
lamsv is offline lamsv  United States
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Default 4th Order Bandpass Driver Selection

Just for fun, I want to build a 4th order bandpass enclosure for my car. My goals is decent volume with low watts. Bandpass should help bump the efficiency, and in the car, give me decent frequency response.

What parameters should I be looking for in a driver for this application? What specs on the speaker itself will lend itself for this situation?

Thanks for any advice or knowledge in advance!

-Seth
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Old 6th May 2010, 10:00 AM   #2
djk is offline djk
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High Qts, Low Fs, high Vas.
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Old 6th May 2010, 04:38 PM   #3
lamsv is offline lamsv  United States
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That is exact information I was hoping for.

Many, MANY thanks!
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Old 6th May 2010, 06:21 PM   #4
Ron E is offline Ron E  United States
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Go to The Subwoofer DIY Page and look at the section on bandpass systems. A bandpass is essentially the same as a vented box, except the radiation from the diaphragm is trapped in the sealed enclosure. You have a little more wiggle room parameter-wise than a vented box, but a high Qts, high Vas woofer will take up your entire car.

Run some woofers through bandpass.xls including cabin gain - it may take you some time to figure it out - the forums there used to be quite good, but I haven't been there in some time.
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Old 6th May 2010, 06:34 PM   #5
lamsv is offline lamsv  United States
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Looked at that site for awhile last night. Some great information on that site. Last piece I was looking for, they didn't seem to have: parameters of the speaker itself that lends itself to a bandpass. You guys filled that portion in for me. Now I'm armed and dangerous!
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Old 6th May 2010, 06:47 PM   #6
lamsv is offline lamsv  United States
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Looking through Parts Express catalog... I cam up with this 10" subwoofer. High Qts (.61), low Fs (27), and high Vas (3.15 cu. ft.).

Parts-Express.com:10" Dual Voice Coil Subwoofer | 10" subwoofer Dual Voice Coil Subwoofer DVC sub car sub home theater poly cone eminence sealed box subwoofer marcato DVSSUB090109

Thoughts?
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Old 7th May 2010, 12:32 AM   #7
lamsv is offline lamsv  United States
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I played around with the box design. This is what I came up with for the box design:

Click the image to open in full size.

Here is what I came up with for the port size:

Click the image to open in full size.

How does the design look? The frequency range, and F3 look good. This doesn't take into account cabin gain either. Tuning frequency seems about perfect for the music I listen too as well.
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Old 7th May 2010, 12:39 AM   #8
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Quote:
Originally Posted by lamsv View Post
Looked at that site for awhile last night. Some great information on that site. Last piece I was looking for, they didn't seem to have: parameters of the speaker itself that lends itself to a bandpass.
That's because *almost* any set of t/s params should work, as you have quite a bit of flexibility with bandpass designs.

The question should really be, what are your main objectives with this design? e.g. do you have any restrictions wrt box size? Do you prefer a punchy bass, boomy bass, flabby bass or clean bass? What sort of output level are you aiming for?
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Old 7th May 2010, 01:11 AM   #9
djk is offline djk
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"but a high Qts, high Vas woofer will take up your entire car."

BassBox v6.0 says you're wrong, so does Mathew Polk.

Years ago Polk wrote an article published in Audio magazine, and offered (esentially) free BP4 software.

Using the parameters I suggested will also maximize the vented box volume, and minimizethe sealed volume; key to being able to make a real sized port without 'chuffing'.
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Old 7th May 2010, 05:28 PM   #10
lamsv is offline lamsv  United States
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I have a hatchback (Acura RSX), so I have a bit of a restriction. I'd be happy with anything 3 cubic feet or less. I prefer clean bass. Volume in a car isn't really an issue.
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