I messed up my port...

[rumproast789 0]

Alright, so I messed up on my port. The port it skinnier and longer instead of wider and shorter. I have a BTL, and whenever it plays the lows, I feel like its not hitting them as hard as it should sometimes. I guess I don't know how its supposed to hit in the 30hz - 38 hz region. People say songs like Juice box will hit hard, and it barely hits hard for me it seems like... Same goes for some other low songs.

Here is a pic of the port in the box:

Here is the port that should be 33hz:

Here is the port now (the 21" measurement comes from the 22", I had to cut an 1" off to get it to equal the port opening on the back of the box):

Could someone tell me what this tuning would be?

[KU40 173]

Kinda need to know the size of the box.

[rumproast789 0]

oh crap, sorry. 44" width, 17" height, 27" depth. 7cb ft internally. Built with 3/4" MDF wood.

[jonbearsmt 919]

bump

[rumproast789 0]

bump

thanks bigjon

BUMPs!

[NB50 206]

"Here is the port now (the 21" measurement comes from the 22", I had to cut an 1" off to get it to equal the port opening on the back of the box):"

That doesn't make to much sense. You should have had to cut 1.5" to get the port height of 5" at the back of the box.

[scottxgtr 9]

what size btl?

im getting around 7.63 cubes after port displacement, not including woofer or bracing. and a 35 hz tuning. tuning is probably a little less that that with the L-turn you got on the end.

[rumproast789 0]

"Here is the port now (the 21" measurement comes from the 22", I had to cut an 1" off to get it to equal the port opening on the back of the box):"

That doesn't make to much sense. You should have had to cut 1.5" to get the port height of 5" at the back of the box.

It really doesn't, it might not be exactly 21" but I figured I cut an inch off. I can go cut .5" off soon.

i guess try it at 20.5 or 21", either way works

[rumproast789 0]

what size btl?

im getting around 7.63 cubes after port displacement, not including woofer or bracing. and a 35 hz tuning. tuning is probably a little less that that with the L-turn you got on the end.

I don't think it is an L turn, is it?

did you do it as internal dimensions or external?

[NB50 206]

After all displacements I got about 7.57ft^3 @ 31Hz.

[rumproast789 0]

After all displacements I got about 7.57ft^3 @ 31Hz.

Did i forget to mention the top is double baffle with flushmount, so 1.5" of mdf?

IDK if you got that, but im fine with 7.57ft^3 at 31 hz

I really hope your right cuz I have absolutley no problem with 31 hz

[NB50 206]

In that case it will be about 7.1ft^3 @ 32hz after all displacements

[rumproast789 0]

In that case it will be about 7.1ft^3 @ 32hz after all displacements

oh lol good stuff.

wow your really helpful. Thanks a lot. I'm going to start figuring out how to calculate this stuff by myself, I can figure out the cubic feet but thats bout it

That didn't turn out bad at all

[scottxgtr 9]

I don't think it is an L turn, is it?

not technically, its like an amputated L.

but the port is measured down the center. so technically your port isnt 21" long. technically its 21" long + 1/2 of the opening + 1/2 of the opening. but because the other half of the L is missing, it might behave a little differently in the real world. ive never run a port like that because of the uncertainty i have about the actual port length.

there is a sticky here on SSA that tells you how to find your port tuning after you have built a box. it involves playing tones and measuring voltages, so anyone should be able to do it.

again, what size BTL?

[NB50 206]

In that case it will be about 7.1ft^3 @ 32hz after all displacements

oh lol good stuff.

wow your really helpful. Thanks a lot. I'm going to start figuring out how to calculate this stuff by myself, I can figure out the cubic feet but thats bout it

That didn't turn out bad at all

nevermind

Edited March 20, 2009 by bromo

[rumproast789 0]

In that case it will be about 7.1ft^3 @ 32hz after all displacements

oh lol good stuff.

wow your really helpful. Thanks a lot. I'm going to start figuring out how to calculate this stuff by myself, I can figure out the cubic feet but thats bout it

That didn't turn out bad at all

nevermind

nvm as in thats wrong ?

I'll take a look at that and start testing.

18" only one of them

[NB50 206]

I sending my head into a whirl. I calculated it with some end correction. It will be more closer to 7.1ft^3 @ 33hz as it shouldn't have to much end correction. not a big difference.

[tezin87 0]

What is your ssf set at on your amp?

[rumproast789 0]

What is your ssf set at on your amp?

I tried to put it at about 20hz. I couldnt tell when i played a 20 hz the effect it was having. I can still play 10hz and 15hz

so it really doesn't make sense. Same goes for my LPF I tried setting aroudn 80hz.

Okay so your saying it shouldn't have made much of a difference and should still be about 33hz?

[KU40 173]

Well the crossover won't completely stop frequencies outside of the crossover point from playing. It's not a brick wall to the frequencies, it's just a slope. So it'll be quieter outside of the crossover range but still play.