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View Full Version : WinISD End Correction Question.



Bun-Bun
07-22-2008, 04:47 PM
Ok so I have been beating my head against the wall for the past hour trying to figure out how to figure out the length of a bent port and then stumbled into end correction topic's and now I am really confused.

What I do know is that the length of the port is the centerline of the port. Also I know that end correction (as applies to designing a port) is the calculated port length is your perceived lenth and you make the physical port lenth 1/2xwidth shorter then your calculated(perceived) port length.

Now I look at WinISD and there is a End Correction box that by default has a number in it or something and when you click on it it has three options 1. two free ends 2. one flanged end 3. 2 flanged ends. Which then change the port length with the first option giving the longest port length.

Does WinISD already take this correction into account then? So if I just have a slot port I would choose option 1 and build my physical port to those numbers?

benchambers80
07-22-2008, 04:48 PM
i think it is half of the flare, counted to the length

Bun-Bun
07-22-2008, 04:50 PM
i think it is half of the flare count to length

flare count?

benchambers80
07-22-2008, 04:51 PM
i think it is half of the flare, counted to the length

fixd?

Bun-Bun
07-22-2008, 04:55 PM
fixd?

That makes more sense yes... but I don't have flare on a slot port.

Also my question is does WinISD already account for this and should I build my port to its length and not modify it at all?

benchambers80
07-22-2008, 04:57 PM
http://img142.imageshack.us/img142/6153/30473817vv2.th.png (http://img142.imageshack.us/my.php?image=30473817vv2.png)

crude

benchambers80
07-22-2008, 04:57 PM
That makes more sense yes... but I don't have flare on a slot port.

Also my question is does WinISD already account for this and should I build my port to its length and not modify it at all?

No end corrcection if you don't flare but if you make turns like a L port then you have to measure down the middle.

Bun-Bun
07-22-2008, 05:05 PM
No end corrcection if you don't flare but if you make turns like a L port then you have to measure down the middle.

Ok so I just measure down the middle and make that dimension the same as the number that comes out of WinISD? What do I do with the endcorrection box? it gives me those 3 options I listed earlier and when I change values then a value goes into that box.

And here http://www.caraudio.com/forum/showthread.php?t=218918&highlight=bent+port+length they are talking about end correction being used whenever a side of the enclosure acts as part of the port... which makes sense and I understand tane 1/2 width of port and subtracting it from the port length to get my physical length but the end correction box in WinISD makes me think it already does this and that I should just select the 1 side flanged option and build to that...

I dont know...

benchambers80
07-22-2008, 05:10 PM
2 free ends

flange generally refers to the actual raised rim or lip. flanged should make it longer

Bun-Bun
07-22-2008, 05:18 PM
2 free ends

flange generally refers to the actual raised rim or lip. flanged should make it longer

Selecting the single or 2 flanged options makes the port shorter (at least in WinISD's calc).

So I select the two free ends and use the number WinISD gives me to make my port? So if WinISD says 30.42" I should make my port 30.42" long or do I subtract half my port width from that?

benchambers80
07-22-2008, 05:20 PM
you are supposed to input your port area into the calc then ot gives you length

benchambers80
07-22-2008, 05:21 PM
Selecting the single or 2 flanged options makes the port shorter (at least in WinISD's calc).

So I select the two free ends and use the number WinISD gives me to make my port? So if WinISD says 30.42" I should make my port 30.42" long or do I subtract half my port width from that?

they must be calc the length w/o the flared ends

Bun-Bun
07-22-2008, 05:23 PM
they must be calc the length w/o the flared ends

Yes I entered my port dimesnions and select the two free ends option under end correction and it gives me 30.42" for my length (and says 0.614 under end correction). So now that is my actual port length or do I subtract 1/2 of port width from that number?

Bun-Bun
08-06-2008, 05:19 PM
OK I found a site that explains it... and now I lost the link. blah. Anyway free ends are like the end of a round port in mid air and flanged ends are where it attaches to the face of a box. So typically car audio boxes are 1 free and 1 flanged end and no additional end correction is nessessary.

Well square ports to act differently but the difference will be like 1/2 a Hz which can happen from lots of other things not taken into account with the calculations... so I am just going to take the 1 free end 1 flanged end value and roll with it!