Hey guys- different day, different question 😉
I used WinISD to calculate my Vented Enclosure, and used the "Port Area" and Tuning Frequency" parameters to put them into subbox.pro
I am getting quite different Port lengths from subbox, and i was wondering if they already calculate the "corner" into the length, and that the difference comes from that, or if there is something else wrong.
Since such a port can't be corrected after building it, i a want to be rather safe than sorry... this time even with pictures 😀
Thanks guys =)
I used WinISD to calculate my Vented Enclosure, and used the "Port Area" and Tuning Frequency" parameters to put them into subbox.pro
I am getting quite different Port lengths from subbox, and i was wondering if they already calculate the "corner" into the length, and that the difference comes from that, or if there is something else wrong.
Since such a port can't be corrected after building it, i a want to be rather safe than sorry... this time even with pictures 😀
Thanks guys =)
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Thanks for the input! I will stick with the "easily doable shorter one" then 😉
Anyway, in this case making it longer, would more or less be micro surgery, since the port is not even 3cm wide, but almost 50cm deep XD
Anyway, in this case making it longer, would more or less be micro surgery, since the port is not even 3cm wide, but almost 50cm deep XD
WinISD counts the rounding on the end in the length (0.7cm on each side), so you need to distract 1.4cm if you don't round the ends of your port to get the real length without the roundings i know from comparing to Virtuixcad and measurements i made.
But you can Set it in WinISD what kind of Port Endings you have... although in practice i can't see that changing the port geometry when i try that, so i might aswell just take it for what you wrote 😉
Since i wanted to add a 12mm Plate on top of the front plate , the Port would get a tad longer anyway, i would try to round the edge to the port on that one anyway, so the rounding will be there-ish
Since i wanted to add a 12mm Plate on top of the front plate , the Port would get a tad longer anyway, i would try to round the edge to the port on that one anyway, so the rounding will be there-ish
Slot ports share walls of the enclosure which will lower the tuning.
Slot ports also have poor efficiency so they tend to give lower tunings from losses.
Winisd will calculate the proper length.
But the end factor correction is not compensating for 3 shared walls.
End Factor Correction for 3 shared walls is different.
Also your end results depends if the displacement of the speaker driver, bracing and ports was calculated correctly. Since in the real world enclosure build. The ports, bracing and speaker remove volume.
So it is up to the designer to calculate the needed Gross Volume compared to the Net Volume you used in the model.
As far as slot ports sharing 3 walls, then yes usually you need to make the length shorter. Since the longer shared walls make the port length seem longer.
Slot ports also have poor efficiency so they tend to give lower tunings from losses.
Winisd will calculate the proper length.
But the end factor correction is not compensating for 3 shared walls.
End Factor Correction for 3 shared walls is different.
Also your end results depends if the displacement of the speaker driver, bracing and ports was calculated correctly. Since in the real world enclosure build. The ports, bracing and speaker remove volume.
So it is up to the designer to calculate the needed Gross Volume compared to the Net Volume you used in the model.
As far as slot ports sharing 3 walls, then yes usually you need to make the length shorter. Since the longer shared walls make the port length seem longer.
The difference doesn't have anything to do with walls.
The difference all has to do with the friction of the air, and in particular the boundary effect.
Which is with a slot port = wide, but narrow, quite substantial.
Another effect that does have effect (maybe that is meant with "walls") is the impedance jump from the port to the air.
Also the flare of the port has an effect on this.
The "end-correction" is some kind of empiric value to compensate for these things.
But not always very accurate.
In WinISD you can change this end-correction value.
I think you're using the newer version of WinISD, which unfortunately contains some major bugs and false values in general, compared to the old Pro Alpha version.
(especially with some of the active filters)
The difference all has to do with the friction of the air, and in particular the boundary effect.
Which is with a slot port = wide, but narrow, quite substantial.
Another effect that does have effect (maybe that is meant with "walls") is the impedance jump from the port to the air.
Also the flare of the port has an effect on this.
The "end-correction" is some kind of empiric value to compensate for these things.
But not always very accurate.
In WinISD you can change this end-correction value.
I think you're using the newer version of WinISD, which unfortunately contains some major bugs and false values in general, compared to the old Pro Alpha version.
(especially with some of the active filters)
Thanks for your Inputs!
Yes, the version I use Is the newest one, and yes, I encountered some of those bugs already, I. E. With port end correction. So atm my enclosure is the best I can scientifically reach with my given skills and tools ��
Yes, the version I use Is the newest one, and yes, I encountered some of those bugs already, I. E. With port end correction. So atm my enclosure is the best I can scientifically reach with my given skills and tools ��
Interesting! I mostly used Pro Alpha [which IIRC, was used to vet the then current version of HR for basic box alignments or vice versa, can't remember] and an early version of it's replacement and they matched plus had some nice new features, so wondering what happened along the way after I switched to just HR.
IIRC some of the most recent ones I posted were from the newer version, but don't remember it being called 0.7.0.900: Downloadable WinISD Pro Files | Home Theater Forum and Systems
Regardless, is there a listing/discussion thread of known issues?
The issue with Linkwitz Transforms is that it does not correctly take across the Fsc and Qtc of the box as set in the box tab, but if you manually input the correct values for those first then it does give sensible results.