PDA

View Full Version : Got a question.



neonrt
04-07-2007, 08:11 PM
Is it ok to use 1/2" mdf for the port walls? i have a plan for a slot port box for my maw 15" but i can only fit it if i can use 1/2" mdf for the port walls. 3/4 is just large enough that i could not fit it in my trunk. has anyone done this before? will it be ok?

thanks

tapout
04-07-2007, 08:13 PM
using it in my box now to help cut down on displacement since the box isnt that large to begin with.

blackbonnie
04-07-2007, 08:15 PM
you shouldnt have a problem

helotaxi
04-07-2007, 10:00 PM
You'd be better off using it for the outer port walls rather than the inner walls that line the main portion ofht e box. Less pressure on the outer walls, less chance the 1/2" will flex.

neonrt
04-08-2007, 07:54 PM
You'd be better off using it for the outer port walls rather than the inner walls that line the main portion ofht e box. Less pressure on the outer walls, less chance the 1/2" will flex.

here is my design, the only 1/2 pieces will be the 2 port pieces.(slot)

http://img183.imageshack.us/my.php?image=portedbox3cf32hzeh6.png

95volvosx
04-08-2007, 08:01 PM
sweet drawing :)

neonrt
04-08-2007, 08:11 PM
sweet drawing :)

it real professional looking isn't it.:)

i sketched it out quick to give an idea of what i was talking about. the 2 port pieces are the only 1/2 mdf. the rest is 3/4.

Immacomputer
04-08-2007, 09:18 PM
I agree with helotaxi. There is not much pressure building inside the port and you would be better off making the far right wall out of 1/2. There will be pressure on the inside port wall though and you're better off using 3/4" there. If you have to make the inside port wall 1/2", you could just add a small brace from the front to the port.

Why is it that you need it to be 1/2" on the inside port wall? Is it honestly the .022 cubic feet of airspace you're losing with the .25" of wood?

Trixter
04-09-2007, 01:31 PM
Why is it that you need it to be 1/2" on the inside port wall? Is it honestly the .022 cubic feet of airspace you're losing with the .25" of wood?


exactly what i was thinking....

neonrt
04-09-2007, 10:18 PM
its actually .049cf for you math guys.:graduate: and yes it makes a huge difference. the outer dimesions of the box is my max size. do the calculations yourselves, i cant have a 3cf box tuned to 31hz in those outer dimensions with 3/4 mdf for ports. the only way possible is to have 1/2 mdf. that extra .049cf means alot to someone with not even .01cf to spare. :)

Immacomputer
04-09-2007, 10:40 PM
its actually .049cf for you math guys.:graduate: and yes it makes a huge difference. the outer dimesions of the box is my max size. do the calculations yourselves, i cant have a 3cf box tuned to 31hz in those outer dimensions with 3/4 mdf for ports. the only way possible is to have 1/2 mdf. that extra .049cf means alot to someone with not even .01cf to spare. :)

I don't think you understand:
http://i18.tinypic.com/2cmvujd.png

The inside port wall should still be able to be 3/4" and you will only lose .022 cubic feet of airspace. Don't believe the math?

http://www.google.com/search?source=ig&hl=en&q=15.5*10.1*.25%2F12%5E3&btnG=Google+Search

neonrt
04-09-2007, 11:14 PM
i guess i misunderstood you. to me the outer wall is the box itself, not that piece of port you showed. but the way you are saying it, i understand about what you are referring to as the inner wall. our math was both right for what we were thinking.

Immacomputer
04-09-2007, 11:30 PM
Yea, I would leave the 10.1" and 11" pieces as 3/4" and do the 14.5" piece as 1/2". There won't be much pressure being applied to the 14.5" piece so you don't need to really worry about flexing.

Trixter
04-10-2007, 08:09 AM
honestly, i would leave it as the inner walls being 1/2" just because they are smaller. the 11" one will be supported on 4 sides and the 10.1" one will be supported on 3.

all bull$h!t aside, i still don't see .0498776785975348237543cu' changing much of any performance or tuning.

Immacomputer
04-10-2007, 11:39 AM
honestly, i would leave it as the inner walls being 1/2" just because they are smaller. the 11" one will be supported on 4 sides and the 10.1" one will be supported on 3.

all bull$h!t aside, i still don't see .0498776785975348237543cu' changing much of any performance or tuning.

While they may be smaller, they will be experiencing much greater pressure than the outside wall. There is not much pressure in a port at all. The air in the port is flowing back and forth and has an entrance and exit point. The air inside the enclosure is being compressed and expanded and doesn't have an entrance or exit point. That compression is what drives the air mass in the port. It would be much smarter to keep those inner port panels 3/4" and make the outside 1/2".

Immacomputer
04-10-2007, 11:39 AM
Double post random bad...