4th order idea

[DylanH]

I was just working on a 4th order design for 2 12's. I talked to Sanitarium about the design I came up with and he said it should work.

2.72 cubic feet ported subs in the ported side tuned to 45hz

.76 sealed per sub

[OldsBoomer]

when figuring the port, the port area should be like 10-16 per cube of the REAR chamber correct? if so then for my 2 12's i'd need from 25-40sq inches which is TINY

[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

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

AH! okay I gotcha now. I was getting confused by the ratio . thanks alot man, now to do a little tweeking. I might have to drop it down to 2:1 just for space issues. or else Ill wack my elbow on it when I get in the car haha

[mbdblue]

I almost forgot, would 47hz be a good number to tune to for daily and on the meter? Im looking for both, and was thinking of sleeving the port

[matt402]

I almost forgot, would 47hz be a good number to tune to for daily and on the meter? Im looking for both, and was thinking of sleeving the port

do u know what ur car was peaking at before?

im gunna try a 4th order for my lvl 5 12" =].

the plan is .8 or .9 sealed & between 1.5-1.8 ported @ 48hz.

ill let u know how it turns out if u remind me lol.

[dwright27]

when figuring the port, the port area should be like 10-16 per cube of the REAR chamber correct? if so then for

my 2 12's i'd need from 25-40sq inches which is TINY

No, you would want to figure it with the size of your ported chamber.

So if you had 3 cubes sealed and 9 cubes ported you would use the size of the potted section to determine your port area.

So your port area could be between 90 - 144 going for 10 - 16 per cube.

Some say bigger, I personally use a 14:1 ratio and sometimes 11:1.

[mbdblue]

I almost forgot, would 47hz be a good number to tune to for daily and on the meter? Im looking for both, and was thinking of sleeving the port

do u know what ur car was peaking at before?

im gunna try a 4th order for my lvl 5 12" =].

the plan is .8 or .9 sealed & between 1.5-1.8 ported @ 48hz.

ill let u know how it turns out if u remind me lol.

I do indeed...it was peaking at 53hz before.

[RAM_Designs]

I like going with sealed:ported ratios in the 1:1 to 1:2 area...even 1:2 can be pretty peaky with certain subs. If you're wanting a big peak, then by all means go for 1:3 or something like that...just don't expect a smooth response curve with it. But for a musical box, it's best to not have a huge ported chamber, in most cases.

Without knowing what subs you're using it's hard to make a solid recommendation though.

[mbdblue]

ah ok....Im actually goin more towards 1:2 ratio due to lack of space. the subs that Im using will be T2000s on 2k a piece daily then 4k a piece for comps.

[Neo_frog]

Why exactly are you going to 45 the sealed chambers?