4th order idea

[mbdblue]

2 12s in a 4th order is what Im after. I have a little space to play with, and I can't get it above the window line which is a good thing. looking at 3 chambers; 2 sealed, middle ported. I was thinking 1.5 cubes X2 for sealed sides and 2.5-3.0 cubes for ported middle; so around 5.5-6.0 cubes total without displacement). port tuning will probably be around 50 hz. what you guys think? I really have no experience with 4th orders so this will be more or less trial and error.

Ive seen too many ported boxes and its time for me to go out on a limb and try this out, so any constructive criticism is appreciated.

[dwright27]

Should work ok.

Do 45 - 60 square inches of port

[uhoh_45]

1.5 seems little big for 12s ...i used 1.5 sealed for my 15s and ended up having to shrink em a little

i usualy use .75-1.25 cube per 12 myself (usually closer to 1")

go with a 2.5/1 ratio tuned to 47sh hz

so example

1 cube sealed x 2

so

2 X 2.5 =5 +2 -7

so youd need 7 cubes before displacement

or you could do a 2/1 ratio to save some space

[OldsBoomer]

Im looking to do one too with 2 12's i was thinking 1-1.25 sealed per and a total of 5-6 ported tuned to 36hz

[uhoh_45]

Im looking to do one too with 2 12's i was thinking 1-1.25 sealed per and a total of 5-6 ported tuned to 36hz

36hz eh haha thats going be tuned looooooow

[dwright27]

Im looking to do one too with 2 12's i was thinking 1-1.25 sealed per and a total of 5-6 ported tuned to 36hz

Holy lows!!

Edit:

Anyone wondering about 4th orders. A bigger sealed chamber makes the box more efficient, a smaller sealed chamber helps handle more power.

[OldsBoomer]

Im looking to do one too with 2 12's i was thinking 1-1.25 sealed per and a total of 5-6 ported tuned to 36hz

36hz eh haha thats going be tuned looooooow

HEHE my last blowthru held a cup at 23hz

Im looking to do one too with 2 12's i was thinking 1-1.25 sealed per and a total of 5-6 ported tuned to 36hz

Holy lows!!

Edit:

Anyone wondering about 4th orders. A bigger sealed chamber makes the box more efficient, a smaller sealed chamber helps handle more power.

yes sir i like lows and i want it be very efficent but i do plan on throwing more power to them then rated so im torn

[mbdblue]

1.5 seems little big for 12s ...i used 1.5 sealed for my 15s and ended up having to shrink em a little

i usualy use .75-1.25 cube per 12 myself (usually closer to 1")

go with a 2.5/1 ratio tuned to 47sh hz

so example

1 cube sealed x 2

so

2 X 2.5 =5 +2 -7

so youd need 7 cubes before displacement

or you could do a 2/1 ratio to save some space

could you expand on that equation a little? 1 cube per sealed, so thats 2 cubes and the center box is 2.5 cubes? how did you get 7 cubes?

thanks alot for the feedback. Im kinda goin in blind

oh and I found a good amount of info on this link:

link to 4th order info

[mbdblue]

looking at each sub sealed chamber being 15 x 16 x 14 @ 1" thick MDF leaves me with 1.26 cubes (with the displacement of sub and 45s should be damn close to 1 cube)

and the ported chamber being 30 x 16 x 16 @ 1" thick leaves 3.18 cubes.

looks like the subs will be inside facing forward and the ported chamber in front of them also facing forward. pretty much like this but will be one port and 2 12s. any downsides for this positioning?

[uhoh_45]

1.5 seems little big for 12s ...i used 1.5 sealed for my 15s and ended up having to shrink em a little

i usualy use .75-1.25 cube per 12 myself (usually closer to 1")

go with a 2.5/1 ratio tuned to 47sh hz

so example

1 cube sealed x 2

so

2 X 2.5 =5 +2 -7

so youd need 7 cubes before displacement

or you could do a 2/1 ratio to save some space

could you expand on that equation a little? 1 cube per sealed, so thats 2 cubes and the center box is 2.5 cubes? how did you get 7 cubes?

thanks alot for the feedback. Im kinda goin in blind

oh and I found a good amount of info on this link:

link to 4th order info

you have your sealed partition which is 2 cubes total (for both subs 1 cube each sub) then you got your ported partition which is 2.5 cubes per 1 cube sealed

so think of it as 2 box's your back box which is your sealed box (2 cubes) and your ported box which is 5 cubes so you would add those 2 up and your left with 7 cubes

like so