Thinking about changing my box to a bandpass but not what is best design for 4 pioneer 12s with 2 brutus 2006, 1 5 farad cap, upgrade the big 3 with bigger alt, and 1 extra battery in back just asking if anyone know the best box design for 4 12s. The pioneers are the tw-s3004spl. I am right now thinking about a bandpass box for a 2004 chevy avalanche but should I go with a 6th order or 8th order. Or let me know if you have a better design because they are now in a ported box tuned at 37hz.
please help
Bandpass boxes are very tricky to design and make sound good.
If you really want a bandpass box I'd go to www.hexibase.com and talk to pete...top notch acoustic engineer
If you really want a bandpass box I'd go to www.hexibase.com and talk to pete...top notch acoustic engineer
Do you have any specs on these woofers? Without them anything you do is guesswork.
#1-Bandpass boxes are big. The best alignment (which "order" you use) will depend on the speaker's specs, how much room you have to spare, and what your performance requirements are.
You should be able to make 4-12's deliver whatever you want with a standard sealed or ported box, and avoid the hassle of bandpass.
Unless of course, you just want to experiment. That's what this group is about!
Tim
It can only be an estimate from the outside dimensions, but port size looks about right for 35Hz.
Your dimensions come up to 4489 cu in per speaker outside.
Subtracting about 20% for 3/4" wood and subtract another 145 cu in for the woofer leaves about 3450 cu in internal volume.
Your vent has the same surface area as a 3.2" dia round port.
Tuning 3450 cu inches to 35 Hz would require a 3.2" dia port 6.5" long.
That's assuming your port dimensions are inside measurements.
I would expect some port noise from the narrowness (1-1/4"), and if extreme, it may translate into an effectively smaller port.
But overall, the first thing I notice is that's a pretty big box for those 12's. The tuning target of 37Hz is good for that speaker in that box, but they would work well in less than half that volume. You may see better power handling in a smaller box as well.
Tim
Your dimensions come up to 4489 cu in per speaker outside.
Subtracting about 20% for 3/4" wood and subtract another 145 cu in for the woofer leaves about 3450 cu in internal volume.
Your vent has the same surface area as a 3.2" dia round port.
Tuning 3450 cu inches to 35 Hz would require a 3.2" dia port 6.5" long.
That's assuming your port dimensions are inside measurements.
I would expect some port noise from the narrowness (1-1/4"), and if extreme, it may translate into an effectively smaller port.
But overall, the first thing I notice is that's a pretty big box for those 12's. The tuning target of 37Hz is good for that speaker in that box, but they would work well in less than half that volume. You may see better power handling in a smaller box as well.
Tim
how many ports do you have? 1 or 4?
if you are using 3/4" mdf , subtract 1.5" from all given dimensions you end up with internally:
w=48.25
L=17.5
h=17.5
=8.55 cuft / 4 = 2.13 cuft each .. seems ok, could be a tad bigger though, but shouldnt hurt much....your losing about -3db on the really low stuff though...
BUT your port is WAYYYYY too small....you want around 14"-16"square inches of port per cuft.....so if you go with 14" square inches, for a box volume of 8.55 cuft...youd need 119.7 sqin's and the port is going to have to be around 18"-22" long
no need to divide the chambers.
the port is going to take up some of the internal volume...
can you tell us the current placement of the subs? or better yet post a pic, so we can try to save the box? have to try and figure out where we can put a slot port.
if you are using 3/4" mdf , subtract 1.5" from all given dimensions you end up with internally:
w=48.25
L=17.5
h=17.5
=8.55 cuft / 4 = 2.13 cuft each .. seems ok, could be a tad bigger though, but shouldnt hurt much....your losing about -3db on the really low stuff though...
BUT your port is WAYYYYY too small....you want around 14"-16"square inches of port per cuft.....so if you go with 14" square inches, for a box volume of 8.55 cuft...youd need 119.7 sqin's and the port is going to have to be around 18"-22" long
no need to divide the chambers.
the port is going to take up some of the internal volume...
can you tell us the current placement of the subs? or better yet post a pic, so we can try to save the box? have to try and figure out where we can put a slot port.
you werent kidding when you said bad pic...sorry but i cant make out anything in the pic.. 
i need to see the full box or atleast where the ports are located.
which way is it even facing?
you just need one port if its one box, if two boxes than one port in each box.
i wouldnt go to bandpass until you learn ported... you cant hear or smell when a sub is going past its limits in a bandpass...in a ported you can hear and smell.
i need to see the full box or atleast where the ports are located.
which way is it even facing?
you just need one port if its one box, if two boxes than one port in each box.
i wouldnt go to bandpass until you learn ported... you cant hear or smell when a sub is going past its limits in a bandpass...in a ported you can hear and smell.
the sub are facing the inside of the truck (avalanche) and the port are located on the bottom. The ported sized i got from the pioneer spec and from a program that gave the ported sizes and will come to 37hz but do you think I should have it around 50hz. I have four different ports with each sub having its own chamber. One more thing is 3 sub better that 4?
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So i should stay with a port box and don't think about bandpass? Ok well I think I will build the box over and make it one common chamber and one port for all. This times I will not use termnials on the box. Finally you'll thing I should keep the same box size or change it the way it look. One more thing is 3 sub better that 4?
Vas is only 1.3 cu ft, Qts is moderate at 0.32. Why should the enclosure be so large?
I would expect the the larger enclosure to have a droop in frequency response and reduced power handling.
And instead of rebuilding the entire box for another of the same volume, just rebuild the ports with more surface area?
Tim
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