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Topic Review (Newest First)

08-19-2009 08:49 PM

matt.u

Re: How to calc port length...

what i did wrong lol i measured the port wall

08-19-2009 07:38 PM

Fallen

Re: How to calc port length...

Just use Sketchup, and draw a line in the middle of the port. The port length follows the middle. It makes it a lot easier to figure out. Or go by my last post. It's a really simple concept, don't over complicate it. The length is simply measured at the middle of the port.

08-19-2009 02:31 PM

Beatdown337

Re: How to calc port length...

Ok so basically when calculating port length i just need to take the length of the actual port itself, add .75 to it for the thickness of the wood, and then if it uses one of the box walls for the port then i ass half of the port width to it as well?

07-24-2009 04:11 PM

Fallen

Yeah it's exactly 30" and the box is actually

2.049479 cuft tuned to 33.73 Hz But close enough...

You can think of it as 14"+12"+.75"X2(thickness of the wood in 2 places adds to the port length)+1.25X2(half the port width adds to the length in two places).=30"

07-24-2009 03:50 PM

xseveredveganx

Quote:

Originally Posted by Fallen

IS that one of my boxes lol?

30" is what I get looking at it, but my mental math could be off.

Can you tell me which box it is, I'll just use sketchup to determine the port length lol.

It's the 2 cubes at 33hz box.

07-24-2009 03:33 PM

Fallen

Quote:

Originally Posted by Beatdown337

So as an example what would the port length on this box be?

IS that one of my boxes lol?

30" is what I get looking at it, but my mental math could be off.

Can you tell me which box it is, I'll just use sketchup to determine the port length lol.

07-24-2009 03:19 PM

xseveredveganx

Quote:

Originally Posted by Beatdown337

can anyone else help?

If I'm not mistaken, the total port length is 28". The first leg of the port is 14", then add the 3/4" baffle = 14-3/4". Half the port width, 2-1/2 / 2 = 1-1/4. Add the 1-1/4" to the 14-3/4" and totals to 16". Ultimately add the 12" of the second side of the port to the 16" coming to the answer of 28".

Math 101.

07-23-2009 07:13 PM

Beatdown337

can anyone else help?

07-23-2009 04:58 PM

Beatdown337

Its just one of the pre designed boxes that fallen did in the enclosure section. Port L1 is 1' 2" and port L2 is 1' and it is using a wall

07-23-2009 04:52 PM

xseveredveganx

Work blocks photobucket so I can't see the picture.

07-23-2009 04:52 PM

Beatdown337

Would it be 27.25?

07-23-2009 04:50 PM

Beatdown337

So as an example what would the port length on this box be?

07-23-2009 04:42 PM

xseveredveganx

Quote:

Originally Posted by Beatdown337

I know that this is a really old thread that im bumping but im just tryin to understand how do you know where and exactly what to count to know the port length. Its like it stops somewhere in between right? Help please

What do you mean? Like Kickerlivinloud stated, if your calculated slot port (and you're using a port wall as a side of the port) 4" wide x 15" tall x 36" long, then subtract half of the width. Therefore the port would be 4" wide x 15" tall x 34" long for the same tuning.

Play with the lower part of this online calculator.

http://www.carstereo.com/help/Articles.cfm?id=31

07-23-2009 04:29 PM

Beatdown337

Quote:

Originally Posted by Kickerlivinloud

I also forgot to add the "end correct factor" This is very easy to understand though. When your port uses a wall

You will need to calculate for "end correct factor". All you need to do for this is take half of your port width and add that to your port length (ex: port width = 4") take half of that (2") and add it to your length. This will give you a proper and accurate port length.

Again, only calculate for end correct factor if you port uses a part of the wall.

Jon

06-12-2007 11:50 PM

Jaco

PM'd you some help

06-12-2007 11:23 PM

xseveredveganx

I've been calculating my a$$ off for the past couple of hours trying to figure out an enclosure for an 06 RE XXX. I keep coming up with crazy high numbers for port area and port length. I thought maybe everything was in cu ft, but I doubt it.

I'm going nuts. Too much Rockstar and boredom do get the best of me while at work. Lol!!

Another quick question, has anyone made a program for their TI-(whatever) calculator? I know I made a solid volume calculator once for my TI-86 when I was in high school. And if they have, maybe shaaaaaare? HMMMM!?!?

06-12-2007 11:14 PM

Beginer

Quote:

Originally Posted by Kickerlivinloud

If my box port uses a part of the wall but port is short. Let's say from first example my blue port wall is only 7" long. So I need to take half port width and add it to port length? So my port long will be 9" ?

Thanks.

02-26-2007 04:52 PM

Used2Know

rock on, just glad to have helped, I wonder if this will make a sticky… I tried this a few months back and it was lost during the db error but even before hand it wasnt stickified which imho this should be for how many questions regarding port length along with the favored over use of those inaccurate online calculators, good luck, I vote sticky…

02-26-2007 04:42 PM

Kickerlivinloud

I had some errors in my original post. I have fixed them all. Everything should be correct now!

Jon

02-26-2007 04:33 PM

Used2Know

Vb should be the net volume after all displacements…

and...

Lv = Av*1.84*10^8/[vb*1728*(Fb/0.159)^2]-0.823*sqrt(Av)

or

Fb = .159*SQRT[(Av*(1.84*10^8)]/(Vb*1728*[Lv+(.823*SQRT(Av))])

Vb is true net volume (all displacements taken into account)
Fb is the enclosures resonant frequency (tuning)
Av is the cross-sectional area of the port (port area)

(area of a circle is pi*r^2)
(area of a rectangle is h*w)
Lv is the length of the port

02-26-2007 03:40 PM

Kickerlivinloud

I also forgot to add the "end correct factor" This is very easy to understand though. When your port uses a wall

02-26-2007 01:15 PM

Kickerlivinloud

How to calc port length...

Ok, I know the not everyone knows how to properly calculate port length and there will always be ppl ask how so I took the time to day to break it down in an easier way.

If you have any questions or didn't get exactly what I was saying feel free to get at me.

My AIM is Kickerlivenloud or PM me and we can work something out.

Jon

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