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chefboyrlee
03-25-2005, 01:53 PM
i have a wagon. i have a rear firing sealed enclosure. i'm debating on a ported box. what design do you recommend?
subs firing and up and ports firing rear?
both subs and ports firing rear?

also, can a wedge type box be slot ported given the setups listed above?

should this be in general discussion?

Moe Lester
03-25-2005, 02:42 PM
subs up and ports rear.

chefboyrlee
03-25-2005, 03:26 PM
would something like this work?

req
03-25-2005, 03:29 PM
yes. that would work lovely. called a CRX box.

chefboyrlee
03-25-2005, 03:35 PM
sweet! math time

chefboyrlee
03-25-2005, 06:08 PM
can someone check the calculations for this box.
i am a newb so bare with me.

so the box will be designed like the picture above.
it wil be for 2 12"s prolly RE SX (if i can ever get a hold of them).

1" MDF or 3/4" (i dont know how a box like this would be braced)

so the external dimensions are as follows
Height = 16"
Width = 37"
top depth = 14"
bottom depth = 23.25"

as for the port, i dont think i'll have to build the part that goes up (in the pic)
Slot height = 1.5"
slot width = 17"
slot depth = 21"

are these calculations correct?

i believe the this will net about 4 cu ft after all displacements

chefboyrlee
03-25-2005, 07:38 PM
anyone? maybe u have a program where u can check the math?

Moe Lester
03-25-2005, 07:54 PM
you can build it like that no problem, just use 3/4" MDF and put in a center divider so it is 2 seperate chambers. that will be all the bracing needed.

chefboyrlee
04-03-2005, 09:00 PM
the external dimensions are as follows
Height = 16"
Width = 37"
top depth = 14"
bottom depth = 23.25"

as for the port, i dont think i'll have to build the part that goes up (in the pic)
Slot height = 1.5"
slot width = 17"
slot depth = 21"


what will the port tuning = with these specs?

req
04-03-2005, 09:14 PM
draw a picture and put numbers on. if you do that i can CAD it up and see what it comes out to :)

JimJ
04-03-2005, 09:38 PM
draw a picture and put numbers on. if you do that i can CAD it up and see what it comes out to

but yet nobody responds to my thread about my box designs :(

chefboyrlee
04-03-2005, 09:41 PM
the slot height his 1.5"

chefboyrlee
04-03-2005, 09:42 PM
i can't upload my ghetto picture

figured it out

i forgot to mention, crx style box (subs up )

chefboyrlee
04-03-2005, 09:49 PM
jack frost,
i'd love to help u out...but i'm kind of newbieish

JimJ
04-03-2005, 10:10 PM
I don't want to jack your thread with my tomfoolery...:)

Reply over in my thread about my box woes if you're interested, heh.

chefboyrlee
04-03-2005, 11:02 PM
when a speaker calls for a 1.9 cu ft ported. does that include the volume of the port as well?

Acidburn
04-03-2005, 11:23 PM
no

chefboyrlee
04-04-2005, 07:16 PM
ok, another question, regarding port tuning. i've been running the numbers through 12volt.com along with other calculator programs. when calculating the tuning for a slot port in relation to round ports, is it true that as long as the volume of the air inside the round port equals the volume of the slot port, the tuning will be the same?

its_bacon12
04-04-2005, 07:36 PM
no tuning will be lower with slot ported than with round, there is more surface area in the port, thus more friction and slower air movement...

effectively tuning the port lower than desired - always keep this in mind when designing slot ported

chefboyrlee
04-04-2005, 08:27 PM
say im using 12 volts site. if i want 32hz tuning. do input a higher hz in the formula? since slotted porter will be lower, i should input say 37hz (whats a good number to offset)?

http://www.the12volt.com/caraudio/boxcalcs.asp

here's an example. the dimensions of my slot port will be about 1.5" x 18.38"
1.5 x 18.38 = 27.57

conversion of area into diameter
27.57 = 3.14r^2
8.78 = r^2
2.96 = r
Diameter = 5.92

so...
D(diameter) = 5.92 Vb(net volume of box) = 2.0 Fb (tuning frequency) = 32hz

i get port length of 31.89
then in order to calculate the correct length of the slot port, i would calculate the volume of the round port. then using my 1.5 x 18.38 of the slot determine the length by getting the same volume?

also since its goin to be a slot port i should set the frequency higher?


thanx in advance whoever can help me...

Spkrman
04-04-2005, 08:30 PM
no tuning will be lower with slot ported than with round, there is more surface area in the port, thus more friction and slower air movement...

effectively tuning the port lower than desired - always keep this in mind when designing slot ported

more surface area, so more friction...?

That is VERY untrue!

More area = higher tuning, less length = higher tuning.

Less area = lower tuning, more length = lower tuning.

Only if your slot port is very skinny will it screw up tuning.

chefboyrlee
04-04-2005, 08:36 PM
whats considered skinny?
is it the ratio of height to width
or is there a numerical value for skinny...say under an inch?

ngsm13
04-04-2005, 08:46 PM
whats considered skinny?
is it the ratio of height to width
or is there a numerical value for skinny...say under an inch?

Get WinISD!

i think it's
www.linearteam.tk

If not, just google it...it's free. Then (copied from old convo I had on AIM...
[12:21] ngbd13: input your desire NET volume
[12:21] ngbd13: and tuning
[12:21] ngbd13: THEN design desire port area
[12:21] ngbd13: it will give you the port length!
[12:21] ngbd13: then...
[12:22] ngbd13: (Port area X Length)/1728 to get port displacement
[12:22] ngbd13: add that to NET volume, and add .3 for sub displacement
[12:22] ngbd13: that is your NEEDED gross volume
[12:22] ngbd13: :)
[12:23] UNDERC0VERPUNKER: alright, time to start knocking out numbers
[12:23] ngbd13: THEN!!!!
[12:23] ngbd13: State two dimensions of the box that you want, and solve for the third side....
[12:24] ngbd13: (L x W X H)/1728 = Gross Cubes
[12:24] UNDERC0VERPUNKER: yep
[12:24] UNDERC0VERPUNKER: good old geometry
[12:24] ngbd13: So, (1728 * Gross cubes)/(L x W) = Height
[12:24] ngbd13: or something
[12:24] ngbd13: WOOOOooooooooooooooooooooHOOoooooooooooooooooooooo o!!!!!!!!


NG

Spkrman
04-05-2005, 02:14 AM
www.linearteam.dk

Doesnt really help ya with the skinny port thing.

The ratio is normally 8:1

But I like to stay within 5:1