Functionally, it doesn't matter whether the ports are on top or bottom.
Practically, I'd put them on bottom to minimize the effects of port noises. Just be sure the area around them is clear so airflow won't be hindered.
BTW, round PVC ports are much easier to remove, trim and replace if you want to fool around with tuning.
Tim
Practically, I'd put them on bottom to minimize the effects of port noises. Just be sure the area around them is clear so airflow won't be hindered.
BTW, round PVC ports are much easier to remove, trim and replace if you want to fool around with tuning.
Tim
bullfrog, a problem with this box is that it doesnt appear that you are able to place the subs across in a straight line, you have to stagger them so they fit right ?
if you think you can make them fit, run the port along the bottom...you may have to do a V indenture.
if you have problems fitting them, bandpass is looking like a good option...everything will fit easily, you could even put plexiglass on the top of the box and open the bed cover and show the subs.
heres a couple of pics:
if you think you can make them fit, run the port along the bottom...you may have to do a V indenture.
if you have problems fitting them, bandpass is looking like a good option...everything will fit easily, you could even put plexiglass on the top of the box and open the bed cover and show the subs.
heres a couple of pics:
An externally hosted image should be here but it was not working when we last tested it.
i dont have any experience with your subs in bandpass...so what i would do when i run into something im not sure of is...
make the two grey boards adjustable, and slide them back and forth until you find the sweet spot....also adjust the length of the port...make the port about 8"x8" wide.
for the middle part of the box:
the larger the volume, the more narrow the bandwidth...stronger peak at a given frequency.
the smaller the volume, the wider the bandwidth...you dont necessarily want a wide bandwidth.
id start off making the box 10cuft total... with each sealed chamber 2cuft, and the middle 6cuft... and go from there.
when you make the port, make a really long one...and cut them into 3-4 different sized lengths between 8"-16", that way you can just plug in different sizes...then fine tune it by cutting it down once you find the 'general' length.
the ported box will work good for sure, for the bandpass your going to have to experiment... but then again all the loudest people dont exactly use 'drop in' specs...
good luck!
make the two grey boards adjustable, and slide them back and forth until you find the sweet spot....also adjust the length of the port...make the port about 8"x8" wide.
for the middle part of the box:
the larger the volume, the more narrow the bandwidth...stronger peak at a given frequency.
the smaller the volume, the wider the bandwidth...you dont necessarily want a wide bandwidth.
id start off making the box 10cuft total... with each sealed chamber 2cuft, and the middle 6cuft... and go from there.
when you make the port, make a really long one...and cut them into 3-4 different sized lengths between 8"-16", that way you can just plug in different sizes...then fine tune it by cutting it down once you find the 'general' length.
the ported box will work good for sure, for the bandpass your going to have to experiment... but then again all the loudest people dont exactly use 'drop in' specs...
good luck!
bulldogfreddy said:
the tuning frequency is determined by the port length, if you tune to 23 hz the port would have to be 51.34" long...much too long
tuned to 34 hz it would be 13.47" long
tuned to 37 hz it would be 8.5" long
id go with 32hz @ 17.59 " long , between 14"- 18" is usually the sweet spot, to short the sub will unload, too long the sub will overheat.
this is for a port with an opening of 48" x 2.47", support the port down the middle.
you calculate the ports volume the same as you calculate the boxes volume.
then add it to the total box volume
to calculate the actual box volume, just start with the center tip of the v backwards....
dont worry about the space that is directly behind the port, the triangular area where the subs are mounted, will compensate close enough for that area....
actually im just to lazy to type everything out, if you take time and think...im sure you can figure it out....
just remember two triangles joined together will form a four sided object....which is close in resemblence to a square.
cuft = W x H x L / 1728........(1728 = 12"x12"x12")<<which equal scuft
then add it to the total box volume
to calculate the actual box volume, just start with the center tip of the v backwards....
dont worry about the space that is directly behind the port, the triangular area where the subs are mounted, will compensate close enough for that area....
actually im just to lazy to type everything out, if you take time and think...im sure you can figure it out....
just remember two triangles joined together will form a four sided object....which is close in resemblence to a square.
cuft = W x H x L / 1728........(1728 = 12"x12"x12")<<which equal scuft
if possible, make the board you put the subs on 2 layers...
when you cut the holes for the subs, take the circles that were cut out , and screw them to the top board from the inside.
also...experiment with the port lengths...you can extend my suggestion with an extension board, and join them by using a board overlayed on top of both pieces and screw them down.
if you have a sander/die grinder...smooth the edges wherever there would be airflowing over it...
remember this: a car turning a corner can turn much faster at a gradual angle than a sharp angle.
once you get the box done, i have a few tricks you may want to implement...
and happy new year! ... im starting on my box soon too, so we will see who finishes first !!!
when you cut the holes for the subs, take the circles that were cut out , and screw them to the top board from the inside.
also...experiment with the port lengths...you can extend my suggestion with an extension board, and join them by using a board overlayed on top of both pieces and screw them down.
if you have a sander/die grinder...smooth the edges wherever there would be airflowing over it...
remember this: a car turning a corner can turn much faster at a gradual angle than a sharp angle.
once you get the box done, i have a few tricks you may want to implement...
and happy new year! ... im starting on my box soon too, so we will see who finishes first !!!
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