About to build my enclosure...Does this 4th order bandpass box make sense? - diyAudio
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Old 14th January 2005, 08:13 AM   #1
treedog is offline treedog  United States
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Lightbulb About to build my enclosure...Does this 4th order bandpass box make sense?

Before I start building this, I was wondering if anyone...

Could confirm if the below box will function properly? Are these volumes even close to correct?

Thanks for any guidance!

I used the following website: http://colomar.com/Shavano/4thorder_info.html

1) Speaker Parameters

Diameter: 10.00 (inches)
Qts: 0.57
Fs: 33.80 (Hz)
Vas: 1.31 (cubic feet)
= 37.10 (liters)
S: 0.50 (response curve - .4 thru .7)

--------------------------------------------------------------------------------
2) 4th Order Bandpass Cabinet Parameters

Lower 3db Rolloff: 35.00 Hz (F3 Provided by user)
High 3db Rolloff: 110.38 Hz (Calculated)

Sealed Box: 0.55 cubic feet
= 950.48 cubic inches
= 15.58 liters

Ported Box: 0.43 cubic feet
= 735.47 cubic inches
= 12.05 liters

Tuning Frequency: 62.16 Hz
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Old 14th January 2005, 08:17 AM   #2
treedog is offline treedog  United States
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Some more specs for the subwoofer I plan on using in this enclosure....


Sensitivity: 86 w/m

Xmax: 12.45 mm

Qes: .603

BL: 19.998

Qms: 10.552

Mms: 163.5 gms

Sd: .0439
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Old 14th January 2005, 02:50 PM   #3
Ron E is offline Ron E  United States
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If you have Excel, use Unibox,

If not, use WinISD pro

The shavano site does not tell you the gain or loss in spl given by teh particular alignment you choose and it does not graph the response. If you want your box to sound good, I would caution against using anything other than an S of 0.7 in those calculations The lower S gets, the more severe the dip in response at tuning gets.

Bandpass boxes should not have any damping material in the vented section, as it reduces output and exagerrates teh vent organpipe resonance which is not damped by damping material.
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Old 14th January 2005, 07:56 PM   #4
simon5 is offline simon5  Canada
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The box looks ok, but it's flat anechoic, so will be louder at 40 Hz than 90 Hz.
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Old 14th January 2005, 09:57 PM   #5
treedog is offline treedog  United States
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Ron, I took your advice and got winisd. I am doing a little fine tuning. Thanks for the suggestion.


Simon, any ideas on changes I could make in size and or port to get a little better out of it? Remember, I need to stay pretty close to this total volume.

Thanks for any other input!!!
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Old 14th January 2005, 10:31 PM   #6
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As alluded to previously (though I don't know where the 40 Hz figure came from) you don't necessarily want flat response or a low passband. Figure out where room gain will kick in (longest room dimension is 1/2 wavelength). Make that the lower corner frequency and the room gain and rolloff will cancel each other out for flat response below the lower box frequency. Of course, this makes the sub only tuned to that room.
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Old 15th January 2005, 05:29 AM   #7
treedog is offline treedog  United States
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Bill, guess I should've stated this...but this sub is going into a car. Actually a roadster with no roof so I'm not sure if I'll be able to take advantage of any boosts from the "room".
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Old 17th January 2005, 12:55 AM   #8
simon5 is offline simon5  Canada
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If you don't have any roof then it's a good idea to design it flat anechoic.

You could have deeper bass with the same enclosure size but you will lose some SPL (about 2 dB).

20 liters sealed with 10 liters ported tuned to 57 Hz is ±2 dB from 30 Hz to 115 Hz.
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