PDA

View Full Version : is this box calc accurate?



60ndown
07-04-2005, 07:55 PM
http://www.accelerator-pedal.com/l-ported-box.htm

60ndown
07-04-2005, 10:39 PM
b.u.m.p.!

geonfreaq
07-05-2005, 11:04 AM
its just blank.

Moe Lester
07-05-2005, 12:13 PM
seems to me that it doesnt really give enough port area for many high excursion subs.

dbornotdb
07-05-2005, 01:39 PM
I ran a couple subs through there that I had built boxes for. It was pretty **** close to what I had come up with using winISD and BBP6. The port came out smaller, but not to small as to make a noticable difference in my opinion. Hell, mine could have been to big. I'm not perfect at it.

60ndown
07-05-2005, 07:33 PM
thanks...............
ill start messin wit it -an buildin! :crazy:

beerman
07-06-2005, 01:07 PM
seems to me that it doesnt really give enough port area for many high excursion subs. I can't please everyone. :D

It was designed to make the smallest possible box for a typical daily driver system, given MFR recommendations.

The calculator does hiccup, and I am working on v2.0 to fix the hiccups, among other things.

It will take about 30 seconds to add a checkbox for high SPL, increasing the port area by 33% by changing the minumum port area from 10 square inches per cubic foot to 15 square inches per cubic foot. Would this work, or should I make it even larger?

Ideally, I would take into account woofer parameters and port dimensions to calculate peak port velocity and give the user recommendations if the port is too small or tuning is too low.

Ideally, I would also have all the time in the world. :D

Moe Lester
07-06-2005, 01:31 PM
Hmm, im not sure how much time youve got, but maybe you could program in a few check boxes with different ranges of xmax that could correspond with certain port areas. If the sub has a relatively low xmax, maybe the calculator could figure in 10 sq in per cubic foot. If its got a mid range xmax, maybe give it 15 sq in, and if its got a very high xmax, give it even more.

15 sq in per cube would be pretty good :)

beerman
07-06-2005, 02:00 PM
We'll go with 15/cube for right now. The hiccups are a bigger priority.

Wanna see it hiccup? Enter one cubic foot enclosure volume, 12" external height, 24" external width, 0.12 cubic foot driver displacement, and 21hz tuning. Note how long the violet board is in relation to the black board. :D

I just looked at the code again. The bottom says "rounds to nearest 1/16th" but it actually rounds the measurements to 1/4". Whoops, I just made it easier to build. :D

beerman
07-13-2005, 12:59 PM
V2 is almost ready. Hopefully tonight. :D

theCybe
07-13-2005, 01:08 PM
* Keep us updated; I love it.

:cheers:

beerman
07-14-2005, 12:27 AM
Version Two (http://www.accelerator-pedal.com/ported-box.asp)

norcalSRTrida
07-14-2005, 12:43 AM
v.2 is lookin great


by NET volume...does that mean volume befor port and sub displacement size?


its after the displacement correct?

beerman
07-14-2005, 09:37 AM
It rounds off every measurement to the nearest quarter inch as soon as they're made.

I think I could remove the first rounding of port length (until it's time to display) for a touch more accuracy in the violet panel.

But in the grand scheme of things, being off within half a percent in terms of net volume and tuning frequency isn't bad at all, considering that the Vas measurement of a woofer will be off by as much as 20%.

slicks5150
07-14-2005, 10:41 AM
I think the program has some problems like the port lenght says 16.75 (which is correct) but then it says make it 13.5 inches and only .75 at the bend =14.25"
Net Volume: 2.5 cubic feet
Tuning Frequency: 35 Hz
Port Width: 1.75 inches
Port Area: 23.625 Square Inches
here
****** Port Length: 16.75 inches ******

External Dimensions: 25 wide x 15 tall x 16.75 deep.
Board Dimensions and Quantity
Color Count Width Height
Top and Bottom 2 25 inches 16.75 inches
Red 1 22.5 inches 13.5 inches
Yellow 1 16 inches 13.5 inches
Black 1 23.5 inches 13.5 inches
Green 1 16.75 inches 13.5 inches
and here
****** Teal 1 13.5 inches 13.5 inches ******
******Violet 1 0.75 inches 13.5 inches ******

http://www.accelerator-pedal.com/ported-box.asp

am I missing something here???

beerman
07-14-2005, 03:06 PM
If you measure down the center of the port, you'd find that the port length is, in fact, 17.5" ...

0.75" (wall thickness) + 13.5" (teal) + 0.875" (1/2 port width) + 0.875" (1/2 port width) + 0.75" (wall thickness) + 0.75" (violet) = 17.5"

There shouldn't be a violet board at all for 16.75" ...
ACCK!

Include "end correction factor" (subtract port width from overall length since one wall is actually a box wall) and it's all kinds of wrong.

Fark. I have a bit of work to do tonight.

BastardKidKris
07-14-2005, 10:30 PM
beerman for prez

King_Of_Da_Souf
07-14-2005, 11:13 PM
ACCK!

Include "end correction factor" (subtract port width from overall length since one wall is actually a box wall) and it's all kinds of wrong.

Fark. I have a bit of work to do tonight.

don't u subtract half the port width??? Wish i knew more about this ****.

beerman
07-21-2005, 11:24 AM
don't u subtract half the port width??? Wish i knew more about this ****.
Yes, it should be fixed now.

djman37
07-21-2005, 11:41 AM
i like the cutlist at the bottom. Nice work, beerman.

60ndown
07-21-2005, 12:00 PM
yea beerman , nice of you to take the time to put the calc up, even if its a little off sometimes-.. its gonna help a ton of people build good boxes rather than real ****** ones. if you keep makeing it better its gonna put alot of box builders out a buisiness? good for us- bad form them. dont be supprised if someone hacks the calc?

60ndown
07-21-2005, 07:40 PM
Anyone could just look at the source code and either copy or reverse engineer the calculator (not very difficult). Of course, you should at least ask for permission to copy or make modifications to anyone else's work. That's just common decency ...

And, no, I don't think it'll put a lot of enclosure designers out of work ... Not that a lot of enclosure designers should get work either because they don't know WTF they're doing ... Part of having someone else design an enclosure for you is having their experience, knowledge, and expertise in deciding what enclosure is best for you and your application ... This calculator can't do that ...

Good job on the calc, Beerman, I can't seem to find any mistakes yet ... I'll let you know if I find any, though ...


i tried an online box calc guy recently, calced-box and cut sheet were different? tuneing was effected by difference in desighn/cutsheet-box sounded like ****! and he is supposed to be good-he did send me my $10 back tho!
im not gonna say who it was, that just wouldnt be nice

DrtySthV6SE
07-22-2005, 12:41 AM
dude that awesome, got the same cals i got for my new box :thumbupw:

Mr. Opportunist
07-22-2005, 02:18 AM
what if we have a set depth that we need?

Decipha
07-22-2005, 02:51 AM
what if we have a set depth that we need?


then you plug in different dimensions to get what your looking for

bimma85
07-22-2005, 03:15 AM
I can't please everyone. :D

It was designed to make the smallest possible box for a typical daily driver system, given MFR recommendations.

The calculator does hiccup, and I am working on v2.0 to fix the hiccups, among other things.

It will take about 30 seconds to add a checkbox for high SPL, increasing the port area by 33% by changing the minumum port area from 10 square inches per cubic foot to 15 square inches per cubic foot. Would this work, or should I make it even larger?

Ideally, I would take into account woofer parameters and port dimensions to calculate peak port velocity and give the user recommendations if the port is too small or tuning is too low.

Ideally, I would also have all the time in the world. :D
It better be right be, I used it awhile ago to design my box :D. I was quite happy with the box btw. I actually used v2, found out about the calculator on a different forum you were posting on. Very thoughtful of ya too take your time and do this. Just wanted to say thanks. :patrioti: :toast:

Decipha
07-22-2005, 04:24 AM
x2 i think its really great what your doing beerman, i'll deff have a new calculator (even tho i always double check with my own calculations)

beerman
07-22-2005, 09:52 AM
I'm putting together V3 specs right now. Sounddomain and deCAF have feedback threads going.

Thecontender
08-07-2005, 11:07 PM
are you implementing the 9:1 ratio suggested for ported enclosures?

bimma85
08-07-2005, 11:11 PM
So what do you have in store for v3 that is new?

DBfan187
08-08-2005, 12:26 AM
It won't let me make my height any bigger than 29".

I want my width to be 42" but it puts 32.5" instead. WTF???

beerman
08-08-2005, 04:31 PM
It won't let me make my height any bigger than 29".

I want my width to be 42" but it puts 32.5" instead. WTF???
It can't make the port fit at 42", so it narrows it until it can.

At 42" wide (and with your specific enclosure volume, box height and tuning frequency), the violet panel is either coming up negative (in the case of an L-port) or the violet panel is longer than the teal panel(s) (in the case of making an accordian port) at anything wider than 32.5".

I don't understand why it won't let you go bigger than 29". Gimme more information. :D

beerman
08-08-2005, 05:01 PM
So what do you have in store for v3 that is new?
Out: I was going to add a double-baffle option, but it won't work the way I originally intended. I have to change boatloads of code for it to work properly. So that's out for V3. :(

In: user-inputs port area as opposed to a high-spl option. People are asking for flexibility.

In: help newbies make box design decisions. Input t/s parameters, spit out maximally flat alignment. User can also select a compact alignment that stays relatively flat (only +1.25db over flat) , but makes a smaller, higher-tuned enclosure. The emails asking "what box for this woofer" are starting to increase. Gotta automate myself out of volunteer work. :D

Possible: Front View, including woofer and port placement, along with magnet assemblies inside the box. This will require that I ask for woofer diameter/shape and the number of woofers. (That's quite a bit of work, that's why it's only "possible".)

Possible: help users determine where they should tune a woofer for a specific volume based on T/S parameters. Not much work, but not much value, either.

Possible: minimum port area based on cone excursion x cone area (assuring user that port velocity will never exceed 17m/s). This requires more input on the part of the end user, but will result in a smoother response at high SPL.

DBfan187
08-08-2005, 07:02 PM
It can't make the port fit at 42", so it narrows it until it can.

At 42" wide (and with your specific enclosure volume, box height and tuning frequency), the violet panel is either coming up negative (in the case of an L-port) or the violet panel is longer than the teal panel(s) (in the case of making an accordian port) at anything wider than 32.5".

I don't understand why it won't let you go bigger than 29". Gimme more information. :DSay I wanted to wall off my jeep.

I have 36"H x 42"W x 34"D.

It won't let me try that one.

StreetSide
08-08-2005, 08:43 PM
Could you explain wich panel is wich like is red the side panel is blackthe front panel and so on.

beerman
08-09-2005, 09:22 AM
Say I wanted to wall off my jeep.

I have 36"H x 42"W x 34"D.

It won't let me try that one.
How large of an enclosure? Tuning frequency?

beerman
08-09-2005, 09:23 AM
Could you explain wich panel is wich like is red the side panel is blackthe front panel and so on.
Red is the speaker baffle. Black is the back. Teal/violet are the inner walls of the port. Yellow and green are the sides of the box.

DBfan187
08-09-2005, 09:34 AM
How large of an enclosure? Tuning frequency?13.04cF, 31Hz

beerman
08-09-2005, 10:14 AM
13.04cF, 31Hz


Net Volume: 13 cubic feet
Tuning Frequency: 31 Hz
Port Width: 5.75 inches
Port Area: 198.375 Square Inches
Port Length: 31.25 inches

External Dimensions: 42 wide x 36 tall x 23.75 deep.
Board Dimensions and Quantity
Color Count Width Height
Top and Bottom 2 42 inches 23.75 inches
Red 1 35.5 inches 34.5 inches
Yellow 1 23 inches 34.5 inches
Black 1 40.5 inches 34.5 inches
Green 1 23.75 inches 34.5 inches
Teal 1 16.5 inches 34.5 inches
Violet 1 6 inches 34.5 inches

Number of 49x97 Sheets of 3/4" MDF: 1.5

I included a driver displacement of 1 cubic feet.

Goldtaz1
08-09-2005, 11:13 AM
Does the calculator take "end correction factor" into account?? When I put in my numbers for my enclosure it didn't. End correction factor is usually calculated as 1/2 of the width added to the original port lenth.

Goldenknob
08-09-2005, 12:59 PM
is it possible to make it able to calculate truck wedge boxes? ported?

beerman
08-09-2005, 02:54 PM
End correction factor is usually calculated as 1/2 of the width added to the original port lenth.
You're thinking about it backwards.

Since the outer wall of the box is the outer wall of the port, it tends to lengthen the port beyond the inner port wall. To correct, you remove half a port width from the inner port.

http://www.jlaudio.com/tutorials/ports/index.html

An end correction factor is necesary because more often than not, one wall of the port is also one wall of the enclosure and this wall extends beyond the end of the port thus effectively adding length to the port One has to remove that length from the inner port wall.

beerman
08-09-2005, 02:56 PM
is it possible to make it able to calculate truck wedge boxes? ported?
That requires a bit more coding and the use of round ports since I don't have neat squares to work with.

beerman
08-22-2005, 09:49 AM
Updated.

Logikalliquid
08-22-2005, 04:09 PM
Updated.

I like it!:thumbupw:

panda714
09-05-2005, 11:00 PM
Red is the speaker baffle. Black is the back. Teal/violet are the inner walls of the port. Yellow and green are the sides of the box.

Can I use the top of the box as the speaker baffle? Would it effect the sound? Sorry for my ignorance i'm a total noobie.

Raven
09-05-2005, 11:35 PM
It would be better to keep the ports and the woofer facing the same direction. Just lie to the program when you give it the width and height.

panda714
09-05-2005, 11:55 PM
What do mean by lying to the program? I have 30 inches for the width and 18 inches for the height for the box i'm gonna build. Well i read on the forums that it would be better to have the port facing the rear of the cabin, and have the sub facing upwards to the window in a hatchback.

Logikalliquid
09-05-2005, 11:58 PM
As long as the depth is enough for your speaker placement you don't need to "lie" to the calculator.

panda714
09-06-2005, 12:03 AM
The depth is 24". So am i good to go?!?!?!

Logikalliquid
09-06-2005, 12:03 AM
unless you have a 25inch woofer your good.

panda714
09-06-2005, 12:16 AM
unless you have a 25inch woofer your good.

lol :laugh: Thanks.

beerman
09-06-2005, 02:08 PM
I thought about adding a "port position" selector box.

Options would be "side", "bottom" and "CRX".

Side is "standard" while "bottom" and "CRX" would have to work around the woofer basket. Difficult since the ports are enormous with those designs.

9:1 ratio with a 40" wide box would yield a 38.5x4.25" port, or nearly 164 square inches. Not really a problem with high-excursion woofers, since the port is going to be that big anyways, but many people wouldn't want that for two or three "entry level" woofers.

bimma85
09-08-2005, 03:21 AM
I thought about adding a "port position" selector box.

Options would be "side", "bottom" and "CRX".

Side is "standard" while "bottom" and "CRX" would have to work around the woofer basket. Difficult since the ports are enormous with those designs.

9:1 ratio with a 40" wide box would yield a 38.5x4.25" port, or nearly 164 square inches. Not really a problem with high-excursion woofers, since the port is going to be that big anyways, but many people wouldn't want that for two or three "entry level" woofers.
:yumyum: You are the man.

Goldtaz1
09-08-2005, 04:19 PM
You're thinking about it backwards.

Since the outer wall of the box is the outer wall of the port, it tends to lengthen the port beyond the inner port wall. To correct, you remove half a port width from the inner port.

http://www.jlaudio.com/tutorials/ports/index.html
One has to remove that length from the inner port wall.


Ok Beerman, I guess I'm still not understanding you here. I went to JL's site and it states "Calculating end factor may sound like it would be more trouble than it's worth, but it's actually quite simple. To calculate end correction factor, simply add one-half of h to the physical length you calculated above (L1 + L2)." Just above this statement it gives a pretty little picture to try to explain. Please help me understand why they say add and you say subtract?

beerman
09-13-2005, 05:31 PM
Please help me understand why they say add and you say subtract?
Simple: the JL tutorial helps you determine the tuning of a box that's already built. Note the formula is "solved" for "Fb" and not "Lv". "Lv" is one of the factors that determines "Fb". Determining the "real Lv" in this case requires you to add to the "physical Lv".

Designing a box from scratch requires one to solve for "Lv" (given "Vb" and "Fb") , and then remove the ECF from the "real Lv" to determine "physical Lv".

A word of advice: real gangsta azz fritters don't flex nutz, cuz real gangsta azz fritters know they got em. ;)

Goldtaz1
09-13-2005, 05:59 PM
Simple: the JL tutorial helps you determine the tuning of a box that's already built. Note the formula is "solved" for "Fb" and not "Lv". "Lv" is one of the factors that determines "Fb". Determining the "real Lv" in this case requires you to add to the "physical Lv".

Designing a box from scratch requires one to solve for "Lv" (given "Vb" and "Fb") , and then remove the ECF from the "real Lv" to determine "physical Lv".

A word of advice: real gangsta azz fritters don't flex nutz, cuz real gangsta azz fritters know they got em. ;)


BWUAHAHAHAHA!!

I really appreciate you helping me understand this because this was the only thing that my spreadsheet had gotten wrong so far.