Need help calculating port in WinISD

[ahl395]

Hi everyone

I am calculating my port dimensions and whatnot in WinISD.

I am using a slot port. From my understanding, the volume taken up by the port should not be included in the "net" enclosure volume. So if I subract that and put the new figure into WinISD, it will change the port again.

So my question is how do you properly calculate the port (not)-including the volume the port takes up? Seeing as it changes the port when you input the net volume with the port included in WinISD...

Thanks in advance.

 

[esgigt]

I ran some tests in WinIsd. I assume the program thinks the net volume does not change when the volume of the vent is changed, so a pure theoretical approach... You got to calculate the proper box-sizes yourself. If you want to calculate the port yourself.... the algorithm is in the program, but I think you can find it on the internet too..

Did you notice that the program also calculates the air-velocity in the vent? The indication is "vent mach" ... yes mach as in speed of sound. If that speed becomes problematic it is printed in red. Quite nice... I'd say.

 

[ahl395]

I ran some tests in WinIsd. I assume the program thinks the net volume does not change when the volume of the vent is changed, so a pure theoretical approach... You got to calculate the proper box-sizes yourself. If you want to calculate the port yourself.... the algorithm is in the program, but I think you can find it on the internet too..

Did you notice that the program also calculates the air-velocity in the vent? The indication is "vent mach" ... yes mach as in speed of sound. If that speed becomes problematic it is printed in red. Quite nice... I'd say.

Yeah, for a pretty amazing program I can't believe it has this huge shortcoming.

Yes I have been looking at the port air velocity. Been altering my measurements to try and get it as low as possible.

I'll have to search around for the algorithm I guess and see what I can do. Assuming I followed WinISD's recommendations without compensating, what would the outcome be? A higher or lower than anticipated tune? and by approximately how many hz?

 

[esgigt]

I wouldn't call it a shortcoming, since it is not a commercial program, but freeware.

I guess, adding a functionality that dynamically (re-)calculates the actual box-sizes icm tuning-frequencies, would be too much of a hassle...

 

[Zero D]

Hi,

"net" enclosure volume = The basic bare box.

"gross" enclosure volume = Including Driver/s, Port/s, Bracinging, Socket Panel, etc etc.

So you need to add ALL the extra volume taken up by the above, to get your final Internal box volume !

Look in the Help File under FAQ's 😉

Q. Does WinISD add brace/driver/port displacements to calculated box volume?
A. From Janne Ahonen (janne@lineateam.org)

No. WinISD doesn't do guessing, and therefore shows net volume for your box. It would be hard to predict, how you are going to mount your driver. Or the port. Or how much and which kind of bracing you are going to use inside your box. For example, you could mount port completely external to the box, which case "usual" guess would be completely wrong. Bottom line is, that you must calculate and add any displacements by yourself to calculated box volume.

 

[ahl395]

Thanks guys 🙂