STUMPED on round port length for my WALL

[WOT]

Just went out and bought 2 sheets of MDF to get started on this tomorrow. Want to wall off the back of my truck, but the design wont work if the port ends up being to long. My design is only 17" deep and uses 2 8" sonotubes

Box dimensions. 37.5 X 32 X 17 (17 depth)

So this box is 10.447 cubes. BEFORE sub, port, bracing.

Im having trouble figuring out the ACTUAL port length Im going to have to cut these dual sonotubes to get a 38hz tune, I get 12.09" with box volume alone, but dont know how to subtract port displacement etc and how that affects my length.

I basically just want a 10.447cube box tuned to 38hz with 8" sonotubes

Click to read more...

 

[WOT]

Hell, I dont even know if an 8" sonotube is actually 8".

Is it?

 

[Notloud00 10+ year member]

port is about 7" too long...... just do an l port. if u want i can calculate u one on the re clalc and itll be just as good...... is it 37.5 wide and 32 tall?

 

[WOT]

7" to long what??? When I did the calcs they were only 12"

Maybe you didnt read that i have TWO 8" ports.....

ANd yes you were right on the dimensions, but Im defientely doing sonotubes.

 

[pr-festiva 10+ year member]

i got a volume of 9.7 after port displacement and the ports being 13.49" long for 38Hz but even at 12 inches that dont leave you a port diameter away from your back wall im guessing thats why a L port was recomended and i agree

 

[WOT]

I dont believe in the port width away form the back wall rule, but @ 13.5" thats just to close

Thanks for your time, another box scrapped lol

 

[pr-festiva 10+ year member]

what about 8'' elbows? the ones for pvc pipe might work out, but im sure they are not cheap

 

[mrogowski 5,000+ posts]

You can run two 6" Sonotubes with ease - ~10" each. Look for the '6+' size which is about 6.5" diameter.

 

[01 S 10 10+ year member]

is my calculator broke? im getting 9.8489 cf just with those measurements up there... not including the wall thickness so 36 x 30.5 x 15.5 internal dimesions get you 9.8489cf

im getting right at 14.95" long each for 8" sonotubes bringing your net volume down to 9cf. still not including sub displacement.. should be a good box for 2 15"s though. the ports are going to be too close to the back wall, there will only be about 1.25" from the end of the port and the back wall.

why dont you try a slot port?

A slot port could be 20" x 6", 15 1/4" long. Giving you 8.2cf after port AND sub displacement. and thats right at 15sq inches of port per cf. 38hz tuning

 

[Xprime4 10+ year member]

that's a lot of airspace for two 15 sd.25. I only got 6.5 net and i'm pretty happy with the way it sound

 

[pr-festiva 10+ year member]

is my calculator broke? im getting 9.8489 cf just with those measurements up there... not including the wall thickness so 36 x 30.5 x 15.5 internal dimesions get you 9.8489cf
im getting right at 14.95" long each for 8" sonotubes bringing your net volume down to 9cf. still not including sub displacement.. should be a good box for 2 15"s though. the ports are going to be too close to the back wall, there will only be about 1.25" from the end of the port and the back wall.

why dont you try a slot port?

A slot port could be 20" x 6", 15 1/4" long. Giving you 8.2cf after port AND sub displacement. and thats right at 15sq inches of port per cf. 38hz tuning

he diddnt say if those were inner or outer dimentions or how thick he was going to make the walls,,things that need to be known