2 SQ HDS3 12's Enclosure

[bgowdy 5,000+ posts]

Jeff's numbers are correct 3.78 net @ 38hz 25 inches long The vent velocity is very low modeled with a 1200 watt amp you can make the port smaller gain more volume which means longer port lower frequency.

im lost with this lol...... what do you mean? i really dont want lower then 37-38hz

 

[CheЯRyMan]

I thought you wanted to go lower my mistake

 

[Jeffdachef 5,000+ posts]

how did you figured that? ive checked it on like 5 different apps and did the math on paper using the 12volt box calcs and got what i got above, the apps of course were not all the same but were close, and doing on it paper thats what i got
subs are .26 (.13 ea)

the port was 5.25 * 11.5 * 22.5 \ 1728 = .79

put it in the apps and then used pencil and paper/12volt.com last and it gave me 36.38hz with 4.25 cubes net

The more the space the port takes up, the longer the port will have to be to achieve the proper tuning because the net cubic feet of the enclosure is getting smaller and smaller means less cubic feet, longer port. You calculate port length of final net airspace, not before the airspace before port displacement. The port walls's thickness also accounts for displacement. You are at the tuning spot you shoot for, but the cubic feet is a little less than you think. Too bad you cant go 13.5 or 14 on the height, you could have gotten two 6 inch round/aeros

 

[bgowdy 5,000+ posts]

The more the space the port takes up, the longer the port will have to be to achieve the proper tuning because the net cubic feet of the enclosure is getting smaller and smaller means less cubic feet, longer port. You calculate port length of final net airspace, not before the airspace before port displacement. The port walls's thickness also accounts for displacement. You are at the tuning spot you shoot for, but the cubic feet is a little less than you think. Too bad you cant go 13.5 or 14 on the height, you could have gotten two 6 inch round/aeros

ive been trying to think of a way to do 2 6" aeroports, honestly if i can fit 13.5 high i think i could make it work. They may not be able to be flared but could still do the job for me. But **** they have to be like 22 inches each as well lol

 

[bgowdy 5,000+ posts]

I thought you wanted to go lower my mistake

yea i 37hz would be the lowest i want, but dont want to be at 40. the 37 give me the amount of low end that i want

 

[bgowdy 5,000+ posts]

The more the space the port takes up, the longer the port will have to be to achieve the proper tuning because the net cubic feet of the enclosure is getting smaller and smaller means less cubic feet, longer port. You calculate port length of final net airspace, not before the airspace before port displacement. The port walls's thickness also accounts for displacement. You are at the tuning spot you shoot for, but the cubic feet is a little less than you think. Too bad you cant go 13.5 or 14 on the height, you could have gotten two 6 inch round/aeros

wait would 13.5 even be enough? would it have to be atleast 13.75? 13.5 would only leave 12 inches internal

 

[Jeffdachef 5,000+ posts]

ive been trying to think of a way to do 2 6" aeroports, honestly if i can fit 13.5 high i think i could make it work. They may not be able to be flared but could still do the job for me. But **** they have to be like 22 inches each as well lol

Here is another idea, for future builds.

http://www.caraudioclassifieds.org/forum/direct-sound-solutions/177623-long-round-ports-small-enclosures.html

Outer diameter does take up a lot of room and the round ports wont work unless you do major modifications or go down to 5/8 mdf for top and bottom and add bracing to compensate

I guess your slot port box will be fine just throw more power to it.

 

[bgowdy 5,000+ posts]

Here is another idea, for future builds.
long round ports in small enclosures - Car Audio Classifieds

Outer diameter does take up a lot of room and the round ports wont work unless you do major modifications or go down to 5/8 mdf for top and bottom and add bracing to compensate

I guess your slot port box will be fine just throw more power to it.

ok so whats the issue with my slot port. it seems that it will be the easiest thing i can do, unless i did 1 6" aero and thats just not enough port

 

[Jeffdachef 5,000+ posts]

Its fine just the airspace will be closer to 3.8 not 4.25.

 

[bgowdy 5,000+ posts]

Its fine just the airspace will be closer to 3.8 not 4.25.

Were did the 1200w amp come from though. I said they would probably see about 1k per sub not 1200w divided between them.

 

[Jeffdachef 5,000+ posts]

Were did the 1200w amp come from though. I said they would probably see about 1k per sub not 1200w divided between them.

I dont think i mentioned anything about amp power lol

 

[bgowdy 5,000+ posts]

I dont think i mentioned anything about amp power lol

The other guy did... Talking about your numbers.

 

[Jeffdachef 5,000+ posts]

The other guy did... Talking about your numbers.

He was modeling it in bass box pro with 1200 watts of signal, its a random signal you can put in to see what your spl potential is.

 

[bgowdy 5,000+ posts]

He was modeling it in bass box pro with 1200 watts of signal, its a random signal you can put in to see what your spl potential is.

Oh I see

 

[bgowdy 5,000+ posts]

He was modeling it in bass box pro with 1200 watts of signal, its a random signal you can put in to see what your spl potential is.

I still don't understand why all my apps ive used are giving 4.25 net after displacements though, and the apps factor in port thickness also