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matt_martin87
03-16-2006, 01:50 AM
Could someone who does calculations using the actual formula tell me if all my specs look alright before I build?

Net volume: 2 cuft
Tuning: 30hz
Port area: 18sqin
Port length~22.5in
Port ratio: 8:1 (12"x1.5")

Thank you.

Edit: Here is the sketchup version I just created:

http://i9.photobucket.com/albums/a63/mathyouakandn/2cf30hz18sqinportedshivaboxplans.jpg

gimpster80
03-16-2006, 02:19 AM
well you can tune a box with a FORMULA all you want but that doesn't mean anything. Every speaker has a different tuning freq to enclousure size. A earthquake sub tunes two octaves lower than any other sub in a 1.0cu ft enclousure. I would say if want it tuned really low, go for 10 to 50% large than the factory specs. 30hz is rather low. if its a 12'' then I would say on the average sealed 1.75 sounds good for 30hz, ported go for larger 2.0cu ft and port it with a 3inch tube about 8-12 inches long or a vent 2.0 to 2.5 by 12 inches long. then vent must be tall as or taller than the speaker or combined speakers height, you can break it up in pieces and make it turn corners as long as you get the length right. for a 15 go for 2.0-2.5cu ft sealed, or 2.5-5.0cuft vented, go for a vent 3-4 inchs wide and 12 inches deep. again it must be taller or taller than the speaker, one mistake do not make, do not place a vent on both sides of the sub, this usually sounds bad. you can place a port on both sides but a vent usually sounds like crap don that way.

Jester1318
03-16-2006, 07:35 AM
using the formula it looks right, maybe shoot for ~22.75 on the length

matt_martin87
03-16-2006, 12:11 PM
I am designing based on information gained from contact with a tech guy at Adire. I have a 12" Adire Shiva and they are made to be tuned very low in the right sized box. They recommend 12.5cuin of port area, but I will be using a little bit more.
Anybody else care to input?

matt_martin87
03-17-2006, 12:27 AM
Bump

gimpster80
03-17-2006, 12:37 AM
12.5 cu/in port area? whatever. if thats what they suggest don't vent this sub. use a port. a single 3 inch port will be fine. the cool thing is they are easy to put in and take out if you make it out of PVC. just cut a bunch of different lengths and see which one sounds the best. I seriously recommend a 1.5 to 1.75cuft box using a larger box requires longer port. these guys at the factory will tell only what 'sounds' best, not what you want. some subs perform terrible at 30hz in factory specs, but a little more air and less boom but more low umph.

nissanrider06
03-17-2006, 12:40 AM
a single 3 in port? :uhoh:

matt_martin87
03-17-2006, 12:51 AM
I know my sig says im using sealed boxes, but I actually have my shivas ported with an 11" long 3"w pvc-pipe port. Boxes are 1.75 net. I want to try different options, like a slightly bigger box and more port area. A 4" wide pvc port WILL NOT fit in this design I'm hoping to build off of. A slot-port would be my only option if I wanted to increase port area.

LuNaTiC
03-17-2006, 12:57 AM
well you can tune a box with a FORMULA all you want but that doesn't mean anything. Every speaker has a different tuning freq to enclousure size. A earthquake sub tunes two octaves lower than any other sub in a 1.0cu ft enclousure. I would say if want it tuned really low, go for 10 to 50% large than the factory specs. 30hz is rather low. if its a 12'' then I would say on the average sealed 1.75 sounds good for 30hz, ported go for larger 2.0cu ft and port it with a 3inch tube about 8-12 inches long or a vent 2.0 to 2.5 by 12 inches long. then vent must be tall as or taller than the speaker or combined speakers height, you can break it up in pieces and make it turn corners as long as you get the length right. for a 15 go for 2.0-2.5cu ft sealed, or 2.5-5.0cuft vented, go for a vent 3-4 inchs wide and 12 inches deep. again it must be taller or taller than the speaker, one mistake do not make, do not place a vent on both sides of the sub, this usually sounds bad. you can place a port on both sides but a vent usually sounds like crap don that way.

It seems to me that you don't have a clue as to what your talking about...

Vincent9515
03-17-2006, 01:10 AM
12.5 cu/in port area? whatever. if thats what they suggest don't vent this sub. use a port. a single 3 inch port will be fine. the cool thing is they are easy to put in and take out if you make it out of PVC. just cut a bunch of different lengths and see which one sounds the best. I seriously recommend a 1.5 to 1.75cuft box using a larger box requires longer port. these guys at the factory will tell only what 'sounds' best, not what you want. some subs perform terrible at 30hz in factory specs, but a little more air and less boom but more low umph.

A 3" port is less than 7 sq. in. of port area.

A larger box requires a shorter port if area and tuning stays the same.

ngsm13
03-17-2006, 01:22 AM
well you can tune a box with a FORMULA all you want but that doesn't mean anything. Every speaker has a different tuning freq to enclousure size. A earthquake sub tunes two octaves lower than any other sub in a 1.0cu ft enclousure. I would say if want it tuned really low, go for 10 to 50% large than the factory specs. 30hz is rather low. if its a 12'' then I would say on the average sealed 1.75 sounds good for 30hz, ported go for larger 2.0cu ft and port it with a 3inch tube about 8-12 inches long or a vent 2.0 to 2.5 by 12 inches long. then vent must be tall as or taller than the speaker or combined speakers height, you can break it up in pieces and make it turn corners as long as you get the length right. for a 15 go for 2.0-2.5cu ft sealed, or 2.5-5.0cuft vented, go for a vent 3-4 inchs wide and 12 inches deep. again it must be taller or taller than the speaker, one mistake do not make, do not place a vent on both sides of the sub, this usually sounds bad. you can place a port on both sides but a vent usually sounds like crap don that way.

No.

nG

PV Audio
03-17-2006, 07:29 AM
It seems to me that you don't have a clue as to what your talking about...
Don't worry about it, he's delusional. Especially the part where 12.5 in of port area is bad, so you should use a 3" round port which is around half.

LuNaTiC
03-17-2006, 09:58 AM
well you can tune a box with a FORMULA all you want but that doesn't mean anything. Every speaker has a different tuning freq to enclousure size. A earthquake sub tunes two octaves lower than any other sub in a 1.0cu ft enclousure. I would say if want it tuned really low, go for 10 to 50% large than the factory specs. 30hz is rather low. if its a 12'' then I would say on the average sealed 1.75 sounds good for 30hz, ported go for larger 2.0cu ft and port it with a 3inch tube about 8-12 inches long or a vent 2.0 to 2.5 by 12 inches long. then vent must be tall as or taller than the speaker or combined speakers height, you can break it up in pieces and make it turn corners as long as you get the length right. for a 15 go for 2.0-2.5cu ft sealed, or 2.5-5.0cuft vented, go for a vent 3-4 inchs wide and 12 inches deep. again it must be taller or taller than the speaker, one mistake do not make, do not place a vent on both sides of the sub, this usually sounds bad. you can place a port on both sides but a vent usually sounds like crap don that way.

I bolded were you made your mistakes....

spudracer326
03-17-2006, 10:06 AM
I bolded were you made your mistakes....



lol..that pretty funny...

Worlddre
03-17-2006, 10:14 AM
well you can tune a box with a FORMULA all you want but that doesn't mean anything. Every speaker has a different tuning freq to enclousure size. A earthquake sub tunes two octaves lower than any other sub in a 1.0cu ft enclousure. I would say if want it tuned really low, go for 10 to 50% large than the factory specs. 30hz is rather low. if its a 12'' then I would say on the average sealed 1.75 sounds good for 30hz, ported go for larger 2.0cu ft and port it with a 3inch tube about 8-12 inches long or a vent 2.0 to 2.5 by 12 inches long. then vent must be tall as or taller than the speaker or combined speakers height, you can break it up in pieces and make it turn corners as long as you get the length right. for a 15 go for 2.0-2.5cu ft sealed, or 2.5-5.0cuft vented, go for a vent 3-4 inchs wide and 12 inches deep. again it must be taller or taller than the speaker, one mistake do not make, do not place a vent on both sides of the sub, this usually sounds bad. you can place a port on both sides but a vent usually sounds like crap don that way.
you sir are some kind of idiot

matt_martin87
03-17-2006, 07:42 PM
Just got back from Home Depot. I decided to go on with the build. I will update with pics in another thread once I start construction.

spitfirees20
03-17-2006, 07:50 PM
No.

nG

:rotflol:

matt_martin87
03-18-2006, 10:33 PM
Edit: (Moved image to beginning of thread)

matt_martin87
03-19-2006, 03:22 PM
I'm bumping one more time before cutting wood. If I'm about to do something horribly wrong, which I doubt, please stop me before it's too late.