the mo mo site gave directions on how to make a ported box but it says it would b tuned to 40 HZ then Fe3 would b 36.5 hz. This is using a 4in diameter port 10 inches long. Could i use this plan and tune it down a bit? God i feel like im askin too much lol

 

well yeah i work at CC and i get discounts there so thats why im doin their stuff. I dont have to kno this kinda shit at CC. I jus need to kno sealed boxes and what amps go good wit wat subs not al this other stuff

 

And i was going to do type R's but they are back back back back ordered. I was thinking of going with the new polk momos?

 

This might work for port diameter. http://www.mhsoft.nl/PortLength.asp

but if not, you can aleady calc it by hand

 

To keep port mach to an acceptable amount for a common chamber box for those 2 12's you would need a minimum of 25.64 sq in of port area or a 5.7" round diameter. Anything less and you'll get some nasty port noise

you could use 2" ports but you'd have to use multiple ports.

by making the port longer you could change the tuning frequency but don't just guess at the length make sure you run it through a calc.

 

Ok I made plans, tell me if this is good

Im going to make a 3 Cu/Ft box for 2 12" Polk Mo Mo Subs. I did some research and found out that 30 Hz would b about the best for rap music. I came up with 3 cu/ft cuz each sub needs 1.5 in a ported app. Im going to make both subs firing up with the port in the middle. Its going to be 12.5 Inches long and the diamater of the port is going to be 4" . Can someone tell me if this plan sounds all good?

 

Way to small a 4" round port is 12.5 sq in of port area. Those two subs tuned to 30hz require 62.5 sq in of port area :o probably have to go with a slot port something like 15x4.25 with a length of 55" :o

check out this port calculator:

http://www.carstereo.com/help2/Articles.cfm?id=31

 

my god this shit is confusing as hell! Ok i got how u got 62.5. Now how do i calculate a port using that calc u sent me? Also how would i figure out how much space that port is going to displace from inside the box? Is it really worth all this trouble to go from sealed to ported?

 

A round port is just a cylinder, right. So to solve for a 4x10 round port we'd just use the formula for volume of a cylinder...

(pi)(radius squared)(height or in our case length)

(3.14)(4)(10)=125.6 cu in or .07 cu ft

A slot port is just (L)(W)(H)

 

Just scroll down the page the length calculator is down there.

Well like I said it depends on what you're after... you'll definately gain some output by going with a ported box.

Honestly, if I were you I'd look into some other subs. Adire audio shiva or tempest would be killer subs and they're cheap too. Two Tempest each in 4 cu ft ported @ 24hz with a 1200.1 on them Watch out! More than enough to satisfy your basshead