View Full Version : Need Quick Help

07-13-2003, 05:32 PM
I'm planning on building a box for my MClass 12, and I'm running into a few problems. It will be 19" long by 13" high and 12" deep. THis gives me 1.715277778 ft^3. In order to tune it to 48 hz for competition, i will need 6 round ports(4"x8.045" each). I was wondering if there was an easier way around all these ports and still be able to keep the port noise down. Please check my measurements to see if I am correct. Any help would be great.

If there isnt a way around 6 ports, would it matter if I had 4 on the front and one on each side?

07-13-2003, 06:11 PM
Ive already tried. I would need 2 slot ports, 4" wide 13" tall and 32.325" long. My box isn't long enough or deep enough, and I'm working with limited space.

07-13-2003, 08:14 PM
19x13x12 are sadly the outer dimensions. I'll be using 3/4" MDF. As for power, I'm using a Memphis PR200, bridged. I could use 4 rd ports, 5"x12.42", and I would be ok on port noise. :banghead:

07-13-2003, 09:05 PM
Bridged(not RMS), yea, it put out 200 at 4 ohms. If that won't tune my box to 48 Hz, I am seriously wrong on my calculations on WinISD somewhere, just havent been able to find where yet.

07-13-2003, 09:15 PM
I'm using Pro Alpha. 30m/s? In the help file it says to keep it under 17m/s. This is probably my problem... Ive bee trying to keep it under 17.

07-13-2003, 09:19 PM
I'm using Pro Alpha. 30m/s? In the help file it says to keep it under 17m/s. This is probably my problem... Ive bee trying to keep it under 17.

yea thats like super low......30 is fine.....and im confused as to why u need 6 diff. ports...why not jus make one big one????

07-13-2003, 09:22 PM
I tried. Due to the small size of my box, and the fact that I was tryin to keep it under 17m/s, the only way I could keep it down was to have several ports.

07-13-2003, 09:29 PM
How can I double check to make sure the ports tune the box to 48 hz? Right now I have 2 rd ports (4x11.57), which gives me a cross area of 25.13in^2. Is this starting to sound right?

07-13-2003, 09:46 PM
Finally, we got the same thing. How can you check to make sure it is tuned to 48 hz?

07-13-2003, 10:33 PM
Will it matter if my port exits out the front or the side?

07-14-2003, 12:01 AM

It won't matter where it exits as long as it has ample clearance (Usually the size of the port is a good guideline, so 4"). You also want the port to have ample clearance inside the box, too (4" from the back wall) ...

However, it's recommended that the port fire in the same direction as the subwoofer. If you're using an aero port, it's achievable (Shorter port required to get tuning frequency). If not, you're going to have to fire out the side ...

What length of aeroport will I need, and where can I get one??

07-14-2003, 12:15 AM
Lv = 27.139 cm (10.685 inches)

Hmmm, maybe not ... Looks like you're stuck going out the side :(

Why? The dimensions of the round port was 4x11.1. Why wouldn't I be able to use a aero port?

07-14-2003, 12:20 AM
Are there any advantages to an aero port? What if I were to drill the hole for the port at an angle so it would run diagnally through the box?

07-14-2003, 12:27 AM
So if i got that, just cut it to 10.685 in. and install it?

07-14-2003, 01:02 AM
Oh ok. As for the 10 character rule, don't ask me. Thanks for all the help.