Port Tuning Help - 30 Hz

[Decipha 10+ year member]

I'm building a bandpass box, can some one please tell me how to get the ported section tuned to 30 Hz. The INTERNAL box volume (of the ported area) is NET - NET - NET - NET - NET - NET - 1.8037008102 cu ft. The OUTTER perimeter of the ported section measures W30 x H16 x D18, im using 1.25" MDF board. I would like to have two 4" inch in diameter ports if possible. TIA

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[Decipha 10+ year member]

BTW, the bandpass box is for 2 subs, i figured i can get the ports length and just do the same thing on the other side for the other sub, but i want 2 ports on each sub, 4 ports total.

 

[JimJ 5,000+ posts]

This is a 4th order BP, I assume?

 

[Rawr-DQ 10+ year member]

1.25" Mdf? ****. I wouldn't recommend doing a bandpass box, it's complicated and probaly not worth it.

However, i'll see if I can help. ^ need more details, how many chambers does the box have, what drivers are you using, what shape and size ports are you using? and what is the design you're doing, got any drawlings or something?

 

[Decipha 10+ year member]

Take it easy, i like bandpass's, and really appreciate the help.

The box has 3 chambers, 1 sealed with the subs firing in a common chamber, and 2 soon to be ported chambers. I got the crappy Rockford Fosgate P112S4 subs. I don't have ports yet but i was planning on making two 4" in diameter ports for each sub but i need to know how long i have to make them. No drawings, just a simple square design, if it helps i can post the measurements.

Nope, this is not a forth order bandpass, the rear of the subs will be ported, the front will remain sealed.

 

[Rawr-DQ 10+ year member]

okay, I got a better picture, and yeah what are the specs? I'll see if I can plug them into bbp6

__________________________________

|----------_|------------|_------------|

|-------_ /T|------------|T\_----------|

|------[_---|------------|---_]--------|

|--|--|---\_|------------|_/-----|--|--|

|__|--|_____|__________|______|--|__|

I'm assuming the common chamber is the sealed chamber.

 

[Decipha 10+ year member]

I'm assuming the common chamber is the sealed chamber.

tru

Specs:

Vas - 107

Fs - 25

Qts - .594

Xmax - 7.7

That's all they list on the RF site.

http://www.rockfordfosgate.com/products/ez2rockford/ModelInfo/ModelInfo.asp?ItemKey=10063597&CategoryDesc=Punch%20Subwoofers

 

[Rawr-DQ 10+ year member]

oh, i'm not worried about the sub specs, bbp6 has a large driver database...Alright I'll see what I can do.

 

[Decipha 10+ year member]

My box doesn't look anything like that, the two subs don't face each other but instead are mounted side by side, the complete box measurements are:

30W x 16H x 25D

i have a center board dividing the sealed section and the ported section, and another divider dividing the two subs so they get their own box.

 

[Rawr-DQ 10+ year member]

I would imagine you should just go with a more coventional design.

I tried to calculate it, but according to you it's more like two bandpass boxes in one. Just sharing some of the same pieces but all there is 4 chambers 2 for each woofer.

Why do you need 2 ports per speaker? You could make one for each that way it will be easier to tune and you won't end up with too small of ports...

Could you atleast put up a drawling?

 

[Rawr-DQ 10+ year member]

Oh btw, heres a manual I was using to get more of the technical specs:

http://www.rockfordfosgate.com/scripts/rightnow.cfg/php.exe/enduser/fattach_get.php?p_sid=lRNG4KCh&p_tbl=9&p_id=272&p_created=1083013881

 

[Decipha 10+ year member]

i'll make it simple, its just a ported box, not a bandpass, the ported section has NET - 1.8037008102 cu ft. internal volume. The outside measurement of the box is 15W x 16H x 18D. I can deal with 1 port but i would really rather 2 for looks since this will be a fancy install, the port(s) will be made with a 4" in diameter round plastic tube. Can you tell me how long i have to make the tube to tune the box to 28-30 Hz. Thanks.

 

[Decipha 10+ year member]

When i put the parameters of the sub and box on WinISD it says to make both ports 5" long for 29.6 Hertz tuning. Is this correct or incorrect? TIA

 

[Rawr-DQ 10+ year member]

if you really want a fancy enclosure, make a fiber glass enclosure!

 

[Decipha 10+ year member]

i'm going to fiberglass the front panel and mirror around the subs with 2 blue neon tubes and a fold down panel for the amp, that illuminates blue when closed. I'll post pics when im done (hopefully soon)