does WinISD calculate end correction into into port length?

[IgnoreMe 5,000+ posts]

Originally Posted by winISD help manualWinISD calculates port length assuming that there are one flanged and one free end, i.e. port is mounted to the wall of the box, and another end is freely inside the box. So end correction factor is 0.732 by default. Port length in box wall is counted to port length. If you want do convert the result to different end correction, then add 0.732 times diameter of the port to calculated port length. This gives you needed acoustical length of port. Then add end correction as you like

End correction

End correction factor is analytically or empirically determined factor, how much port extends beyond its physical ends. For free end, end correction is 0.30665 times port effective diameter. For flanged end, more analytical expression is available, 4/(3·pi) ~= 0.42441 times port effective diameter. Flanged end is calculated assuming that tube terminates to infinite baffle. Which is not exactly true, but.. Following table summarizes various port configuration types and their total end correction factors (refer to above picture to various end types):

Summary of end correction values Port configuration end correction 1 end correction 2 Total end correction

Two free ends 0.30665 0.30665 0.6133

One flanged and one free end 0.42441 0.30665 0.7311

Two flanged ends 0.42441 0.42441 0.8488

Physical port length is obtained by subtracting port effective diameter multiplied by suitable end correction value from port's acoustical length.

shit is like for rocket scientists. all i want to know is:

1) if WinISD says my port length is 32" do i still have to add end correction to it, or is it already included in calculated port length?

2) what the **** is a flanged end? im assuming (from what i can get from that quote, that its just where the mdf over laps one another)

3) what does it mean to have "two free ends"?

Click to read more...

 

[dleccord 5,000+ posts]

take half of the smallest side of your port and add that to the port length, dont bother with the port correction shit; shits confusing as hell.

 

[Mr Cabinetry 10+ year member]

End correction factor is big fukin waste because if ya do use it does nothing more than change the port tuning frequency of the port from that what you wanted to tune the port to in the first place.

Think of like this, say you have a port thats 4" x 16" height x 35" long tuned at a specific frequency, now take half the width ( 2" ) add that to the length of the port which will now be 37" long.

OK, now you changed 2 things, the box volume drops and the port tuning drops from what you originally wanted for the enclosure.

Granted, the change isn't all the great, but it's a change none the less, but, for the anal retentive's out there think and believe they will hear/notice the difference, yeah right.

Now i can see where this would have an impact on a competition level, but for the everyday listener that justs wants to bump, it ain't worth the sweat of crunchin numbers.

 

[IgnoreMe 5,000+ posts]

take half of the smallest side of your port and add that to the port length, dont bother with the port correction shit; shits confusing as hell.

i know how to do it, i was just wondering if WinISD did it for you because, its a lot faster than me having to go by hand and calculator through the equation many times, if for instance, im trying to find the maximum box volume i can get while still keeping a low tune, etc.

mr. cab: yea that does make sense. however, if WinISD calculates it with end correction already included, then your not changing any factors since the rest of your box design, comes from the port length. now if it doesnt include it in, then i see your point that its better to just leave it alone.

 

[W8 a minute 10+ year member]

Granted, the change isn't all the great, but it's a change none the less, but, for the anal retentive's out there think and believe they will hear/notice the difference, yeah right.

Now i can see where this would have an impact on a competition level, but for the everyday listener that justs wants to bump, it ain't worth the sweat of crunchin numbers.

x50 if it's in a trunk vehicle

 

[dleccord 5,000+ posts]

End correction factor is big fukin waste because if ya do use it does nothing more than change the port tuning frequency of the port from that what you wanted to tune the port to in the first place.
Think of like this, say you have a port thats 4" x 16" height x 35" long tuned at a specific frequency, now take half the width ( 2" ) add that to the length of the port which will now be 37" long.

OK, now you changed 2 things, the box volume drops and the port tuning drops from what you originally wanted for the enclosure.

Granted, the change isn't all the great, but it's a change none the less, but, for the anal retentive's out there think and believe they will hear/notice the difference, yeah right.

Now i can see where this would have an impact on a competition level, but for the everyday listener that justs wants to bump, it ain't worth the sweat of crunchin numbers.

big fukin wow... ive never saw it that way in terms of an everyday listerner.

 

[PSturmer 10+ year member]

dont use winisd for port calculation. only use it to find out your peak freq. even this measurement can be very inaccurate. a box tuned to 36hz was .1 quieter than 44hz when i played a 50hz tone. winisd said it would be a 8db difference.

use this site for designing

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

it does end correction for you

 

[Immacomputer 10+ year member]

dont use winisd for port calculation. only use it to find out your peak freq.

Winisd is very accurate in calculating your tuning frequency. Using it to find peak frequencies in an enclosure is a waste of time because of your cars transfer function. The reason why you got the results you have is due to you not understanding your vehicles transfer function.

 

[IgnoreMe 5,000+ posts]

Winisd is very accurate in calculating your tuning frequency. Using it to find peak frequencies in an enclosure is a waste of time because of your cars transfer function. The reason why you got the results you have is due to you not understanding your vehicles transfer function.

so does it include end correction? //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif