12x12" clamshell, need some help here guys.

[berniebp87]

So I`ve been thinking about doing a clamshell for a while now, the subs I`m most likely gonna use is (12) 12" Hertz Show SPL 2x2ohm and 3 dynabel BF8501 (5000watts each). I got about 14 cubes of net volume, according to Torres calculator the tuning frequenzy is 49.9hz, but I don`t know how long the actual port length is (where it ends) I just put the length of the plate behind the baffles. Couldn`t find the recomended box volume of the subs on their site, but here is the link:

http://www.hertzaudiovideo.com/Doc/hertz_SX300D_tech.pdf

Here are some pics of what I`ve sketched up, does it look OK? (even made the measurements in inches just for ya`ll lol)

I am willing to pay someone for the job if I think youre qualified.

Edit: the wall thickness is about 2.5 inches.

Edited September 13, 2010 by berniebp87

[OldsBoomer]

I'd tune much lower if you want to play ANY music.

I'd tune to about 34-36ish if you dont listen to any low music. Also the physical port length is not 6.6" its actually about 31.6" but because the opening is bigger then the back port if you calculate the tunning with the actual" port width you'll be lower then it actually is.

try calculating the the tunning with the height of the port being about 11"H instead of 7.8"

and make the length 31.6" that should change your results on the calculator drastically, and it shouldn't be to far off from your true tunning

[Hugh G. Rection]

and make the length 31.6" that should change your results on the calculator drastically, and it shouldn't be to far off from your true tunning

your right, that will change the calculation drastically. and after that change in calculation, it will be just completely WAY the fuck off. maybe your thinking about some crazy ass quarter wave shit........

Edited September 13, 2010 by Hugh G. Rection

[berniebp87]

I'd tune much lower if you want to play ANY music.

I'd tune to about 34-36ish if you dont listen to any low music. Also the physical port length is not 6.6" its actually about 31.6" but because the opening is bigger then the back port if you calculate the tunning with the actual" port width you'll be lower then it actually is.

try calculating the the tunning with the height of the port being about 11"H instead of 7.8"

and make the length 31.6" that should change your results on the calculator drastically, and it shouldn't be to far off from your true tunning

I have NO intensions of having a 50hz tuning frequenzy, lol I`m aiming for a 35ish tuning frequenzy, I shall try that and see what the calculator says. I`m trying to replicate what Frankie Rio did in his lexus, hoping it will produce decent pressure in the car

Edit: Got a 38hz tuning now (and 7cubes of port volume, lol), that`s more like it

Edited September 13, 2010 by berniebp87

[Hugh G. Rection]

I have NO intensions of having a 50hz tuning frequenzy, lol I`m aiming for a 35ish tuning frequenzy, I shall try that and see what the calculator says. I`m trying to replicate what Frankie Rio did in his lexus, hoping it will produce decent pressure in the car

Edit: Got a 38hz tuning now (and 7cubes of port volume, lol), that`s more like it

are you changing the design, or did you just calculate it the way he said? unless you change the design, your just painting over dirt.

[Boon]

Clamshells don't model like a normal ported box, everyone trying to apply ported box tuning equations to them can just give up now.

Ported clams model closer to a T-Line, Tapped Horn (which is essentially what a lot of them are) or even a series tuned 6th order depending how restrictive the mouth is.

Yes, funky quarter wave shit. There you go, I said it.

[Hugh G. Rection]

Yes, funky quarter wave shit. There you go, I said it.

not quite......

[Boon]

not quite......

Please elaborate.

[berniebp87]

Clamshells don't model like a normal ported box, everyone trying to apply ported box tuning equations to them can just give up now.

Ported clams model closer to a T-Line, Tapped Horn (which is essentially what a lot of them are) or even a series tuned 6th order depending how restrictive the mouth is.

Yes, funky quarter wave shit. There you go, I said it.

what kind of program should i use to get the right results then?

[dwright27]

what kind of program should i use to get the right results then?

trial and error my friend