jmac, can i get a yes or no?

[sumone 10+ year member]

I'm just guessing on this stuff...is this what you're trying to do? find out the length of the port for a particular already_constructed_box at a particular frequency?

known variables:

gross_box_volume

sub_displacement

airspace_required_by_subs

port_displacement = gross_box_volume - sub_displacement - airspace_required_by_subs

net_enclosure_volume (Vb) = sub_displacement + airspace_required_by_subs

cross_sectional_area_of_port (Av)

tuning_frequency (Fb)

so what we need to figure out is

1) port length (Lv)

to do this solve for Lv in

this will give you your port length...

 

[sumone 10+ year member]

eh, probably won't work since I didn't account for material thickness for port displacement....

 

[req 5,000+ posts]

ok here is the deal. RE said the box (what the sub sees) should be 1.2cu. i HAVE NOT MADE THIS YET.

he also said that the port should be 37hz.

i want to make the port FIRST... this is kinda what i want it to look like

i want to build the BASE of the enclosure and the PORT from .375" MDF, then construct the fiberglass relief of the trunk corner. then stretch the fleece over the port and the relief. at this point, i will measure the internal volume, and add 'volume filler' to get it to 1.2cuft AFTER port displacement. my trunk is almost empty, and im sure i can fit a 1.2cuft+port in there no problem. i want the sub to see the 1.2cubes.

so i DO NOT have any of the enclosure made already. i want to have a port made before i start glassing.

hence, i just need the dimensions of a port tuned to 37hz with 1.2cuft of space. as the picture looks, the port CAN stick out, and i want it short and long\wide like people usually do with bigger rectangular boxes and the port that goes up the whole side.

i hope that picutre helps. mine will only have 1 sub tho, if this works, i am going to build that setup for a friend.

so. can anyone fill me in on how to make a slot port BEFORE i even mess with the box.

.375" mdf

11xmax

1.2cubes

37hz

.14 cubes driver displacement

 

[PV Audio 5,000+ posts]

dam bro, u can draw!

 

[req 5,000+ posts]

dam bro, u can draw!

lol thanks. //content.invisioncic.com/y282845/emoticons/moon.gif.9d317aec3339ffe7fde0638df52c628a.gif

it was just a 1 minute render of what my friends trunk was gonna look like the other day, and i figured it would work perfectly for my situation too.

im a graphic artist for a printing company. i do alot of cool cartoons and such. maybe ill post one sometime. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

can anyone help me with the situation above? //content.invisioncic.com/y282845/emoticons/help.gif.cee8f684da1ba626487a8bc51152e1ec.gif PWEAASE?

 

[req 5,000+ posts]

anyone? i thought that last post (with the picture) would clear everything up quite a bit.... //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[Nikuk 5,000+ posts]

ok here is the deal. RE said the box (what the sub sees) should be 1.2cu. i HAVE NOT MADE THIS YET.
he also said that the port should be 37hz.

i want to make the port FIRST... this is kinda what i want it to look like

honestly... i dunno if i would make the port before glassing, with glassng a custom you're net volume can change very easily with a slight mistake. I'm gonna bow out on that note. soory

 

[req 5,000+ posts]

honestly... i dunno if i would make the port before glassing, with glassng a custom you're net volume can change very easily with a slight mistake. I'm gonna bow out on that note. soory

but as long as your net volume is LARGER than what you origionally want, then its not a problem - just pop in a pice of wood or 2 to fill that excess volume and youd be all set.

all i need to know is LxWxH for my port, or a way on how to GET to these dimensions. i will gladly do the math if somone just explains how to do it.