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View Full Version : Couple quick port questions.



PapaGeno21
11-27-2012, 01:41 AM
Doing my first slot ported box.

I understand doing the 45 on the outside wall of the port in the corner of the box, but do I have to do anything to the inside wall? I am NOT going to do any kerf style cuts to round it out, so should I just leave that as the sharp L and then the outside wall has the 45?

Like this?

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/1.jpg

Or do I need to have it with both sides at the 45?

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/2.jpg


Now here is something that screws with me. How do I account for the corner?

Does this equal 20"?

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/3.jpg

Or does this and somehow the corner measures differently?

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/4.jpg



And as far as the face of the box, do I bust out the router to round over the port or does it not really matter?

90% of the boxes I see no one rounds over the outside of the slot port so I am just wondering if it is even necessary.

Thanks!

Sonic.
11-27-2012, 02:04 AM
Use drawing # 2, port width must remain constant, and the length of port is measured along the center line.

PapaGeno21
11-27-2012, 10:09 AM
What do you mean it is measured along the center line?

hispls
11-27-2012, 10:14 AM
What do you mean it is measured along the center line?

Draw a line down the center of the port and measure that. Then take into account the back wall will effectively extend the port by half a port width, so port may act a tad longer than you think.

Rounding anything will never hurt and looks good. Many people don't because they lack the tools.

PapaGeno21
11-27-2012, 10:28 AM
Ok cool.

Now as far as pic 1 and 2. Do most people even bother? Doing pic 1 is easy, doing pic 2 is not so easy.

What happens if I do pic 1 with just a very small piece in the corner to help the bend, or will it still cut my port width down some?

mklett33
11-27-2012, 02:32 PM
Ok cool.

Now as far as pic 1 and 2. Do most people even bother? Doing pic 1 is easy, doing pic 2 is not so easy.

What happens if I do pic 1 with just a very small piece in the corner to help the bend, or will it still cut my port width down some?

Yes people do bother, if you did picture one you would not have a consistent width. Its not as hard as it seems.

The videos in this thread should help a lot with some of your questions.

http://www.caraudio.com/forums/enclosure-design-construction-help/560833-about-make-thread-about-box-design-read-first.html

PapaGeno21
11-27-2012, 03:02 PM
When I get home and on a comp I will watch those vids!

Do you need the 45's in the corners? Does it really make a difference that someone who isn't very into this stuff would notice?

mat3833
11-27-2012, 09:08 PM
the port is all about smooth airflow. and the 45s help the air flow smoothly. you gain a little output as well as reduce port noise. its well worth it IMO. im going to go as far as using PVC pipe each corner for a completley smooth "U" bend AND routing the edge of the inner port wall ends if i can, if i cant i will be 45ing and still route the edge. but i will have a folded port, not an "L" port. im also tuning kinda low, and the lower you tune the issue of port noise becomes more of a concern.

i hope how i explained it makes sense.....

Matt

PapaGeno21
11-28-2012, 02:54 PM
You did thanks man!

mlstrass
11-29-2012, 07:24 AM
Without having a TL and tesing I would not start adding 45's. Some will hurt, some might help, no way to tell unless you test.

I have a box like pic 1, single HDC418 in the trunk of my daily beater. With 1500watts per USACI rules it did a 54.9 in the kick the other week, so pic 1 port style works just fine for daily/music...

SMS
11-29-2012, 10:18 AM
Without having a TL and tesing I would not start adding 45's. Some will hurt, some might help, no way to tell unless you test.

I have a box like pic 1, single HDC418 in the trunk of my daily beater. With 1500watts per USACI rules it did a 54.9 in the kick the other week, so pic 1 port style works just fine for daily/music...

thats some crazy #s (http://www.caraudio.com/forums/usertag.php?do=list&action=hash&hash=s) with a 18 in a trunk off 1500w.
guy i know gets that with 2 18" XLs off 5k- on the dash

jdawg
11-29-2012, 12:25 PM
will you tell a difference in a daily system without 45s? probably not. Chasing tenths no a TL? You might tell a difference, if you have the tools to cut a 45 and round the mouth and edges easily go ahead and do it. If its a hassle dont worry about it.

mklett33
11-29-2012, 02:37 PM
the port is all about smooth airflow. and the 45s help the air flow smoothly. you gain a little output as well as reduce port noise. its well worth it IMO. im going to go as far as using PVC pipe each corner for a completley smooth "U" bend AND routing the edge of the inner port wall ends if i can, if i cant i will be 45ing and still route the edge. but i will have a folded port, not an "L" port. im also tuning kinda low, and the lower you tune the issue of port noise becomes more of a concern.

i hope how i explained it makes sense.....

Matt


KERF! DEWHF@#*$@)

http://www.caraudio.com/forums/enclosure-design-construction-help/531017-kerfing-101-how-kerf-mdf-curved-port-applications.html

mklett33
11-29-2012, 02:38 PM
will you tell a difference in a daily system without 45s? probably not. Chasing tenths no a TL? You might tell a difference, if you have the tools to cut a 45 and round the mouth and edges easily go ahead and do it. If its a hassle dont worry about it.

this.

To me, I am OCD about anything I make, so it get's 45's and kerfed, I dont ike knowing that something wasn't the best it could possibly be, does it make much of a difference, not really for daily driving, but still like I said, Im OCD.

mlstrass
11-30-2012, 04:51 AM
this.

To me, I am OCD about anything I make, so it get's 45's and kerfed, I dont ike knowing that something wasn't the best it could possibly be, does it make much of a difference, not really for daily driving, but still like I said, Im OCD.

Without a TL how do you know it's "the best it could be"?

I did some testing on a 4th order build I did over the summer and added 4" PVC roundovers to various places inside the enclosure. I lost .3 - .6 everywhere I tried them. Would you hear that to the ear, obviously not, but just because on paper it looks good that doesn't mean it really is...

mklett33
11-30-2012, 02:21 PM
Without a TL how do you know it's "the best it could be"?

I did some testing on a 4th order build I did over the summer and added 4" PVC roundovers to various places inside the enclosure. I lost .3 - .6 everywhere I tried them. Would you hear that to the ear, obviously not, but just because on paper it looks good that doesn't mean it really is...

Ugh, this keeps popping up everywhere, "I made an enclosure, tested it, then I added 45's and tested it, and it scored lower." Hmmm wonder why, perhaps because adding 45's removes net volume?

bhsdriller
11-30-2012, 02:36 PM
I've never seen a test with 2 boxes with exactly the same internal volume, one with 45's accounted for in the design and one without

it's always adding them after like you said

PapaGeno21
11-30-2012, 11:57 PM
Thanks for the input guys!

Still debating on if I am going to bother, it is just for daily driving. Never will be measured, and honestly if it is such a close call I don't think it is going to be worth my time.

No one is going to see it or even know the difference regardless.

I am doubling my power as well, so regardless it is going to be louder!

mlstrass
12-01-2012, 03:03 AM
Ugh, this keeps popping up everywhere, "I made an enclosure, tested it, then I added 45's and tested it, and it scored lower." Hmmm wonder why, perhaps because adding 45's removes net volume?

While your statement is correct, how much volume do you think a few 45's take up? Not enough to drop .6 I can tell you that...

PapaGeno21
12-01-2012, 10:54 AM
Doing the 45's will remove approx .18 ish of a cube for my plan. That only adjusts my tuning like .3 Hz... I am most likely going to do pic 2 as it is not that hard and I feel it will be better.

PapaGeno21
12-04-2012, 01:59 AM
Well I built it. Won't have the sub for two weeks but that's ok.

6.22 Net, 4.03 after port and sub displacement tuned at 34hz.

First time using carpet on a box, so be gentle. I decided to carpet inside the port as well. First time using all thread style terminals. I did not want to attempt soldering 8 gauge wire to the radioshack style terminal you cut out the square for and mount on the box. I figured these will be more applicable due to the power going through them.

Decided to go with pic 1. I figured out that putting the 45 in the corner (at the right distance) keeps the port at 5" wide, otherwise it got to 7" in the corner. I know I personally will not notice the difference with the other part having a 45 so I didn't bother.

The circle aint bad for a jigsaw huh! LOL I hate cutting sub holes.

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0658.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0659.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0662.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0663.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0664.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0670.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/IMAG0673.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7633.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7632.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7630.jpg

PapaGeno21
12-04-2012, 01:59 AM
http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7629.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7619.jpg

http://i990.photobucket.com/albums/af24/PapaGeno21/Audio/DSCF7618.jpg

mylows10
12-04-2012, 02:06 AM
looks good.my sale starts fri noon ,ab subs at a great price too