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Weird box

 

Silver Member
Username: Boopers

Lima, Ohio United states

Post Number: 235
Registered: Jul-04
the slot ported box that was made for my 12" shocker super extreme is rather weird.

outer dimensions are 29"x17"x14" using .75" mdf

port is 3.75"x12.5"x13.75"
that gives me 3.99ft^3 gross with a port tune of 39.70hz!! so strange. could I make this box work for my 12" brahma buy adding some polyfill or whatnot or should I just have a new box made by someone who does it right?
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 5304
Registered: Dec-03
It should work fine for the Brahma.
remember to subtract both the sub and port displacement from those dimensions when you figure net volume though. That slot port has considerable volume inside the box.
 

Silver Member
Username: Boopers

Lima, Ohio United states

Post Number: 236
Registered: Jul-04
how would I calculate the port volume exactly

I already know that brahma has .15ft^3 of displacement, that leaves 3.84ft^3 before taking the port into account
 

Silver Member
Username: Boopers

Lima, Ohio United states

Post Number: 237
Registered: Jul-04
ok, after I went through and figured internal measurements and volume of the speaker part of the box I came up with 2.77ft^3 gross, that would be 2.62ft^3 with the sub. But, if I inverted the sub, and added 1 inch of polyfill to the box that would increase the volume to 3.04ft^3 and the port would be tuned to like 43.5hz. Then if I add 1 layer of .75" mdf to the port to narrow it to 3" instead of 3.75" I could get the tune down to 39.25hz. Still just over 4hz higher than recommended. How narrow could I go with the port, or should I add a layer of .75" mdf to the top or bottom part of the port to cut down on volume some more? Basically I'm trying to avoid spending another 200+ on another box for awhile, want to make this box work if I can.
 

Silver Member
Username: Boopers

Lima, Ohio United states

Post Number: 238
Registered: Jul-04
haha, I keep rambling on about this. if I invert the sub, add 1" of polyfill to the box, and narrow the port by 1.25" and lower the height by .75" then I get a port tune of 35.102hz. *rofl* wow that's pretty crazy to take it to that extreme isn't it, I mean I measure it out to .102

anyway, anyone know if adjusting the port that much will cause port noise or not?
 

Silver Member
Username: Boopers

Lima, Ohio United states

Post Number: 239
Registered: Jul-04
winisd tells me that the vent mach is 0.05 *in green which I assume means that it is acceptable* for 3.04ft^3 with a port of 2.5x11.75
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