Rear port and front port air velocity in WinISD

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   Hello,
I have a question about WinISD's front port and rear port velocity.
I'm simulating a woofer for a 2 way bookshlef loudspeaker and I want it vented.
I'd like to put the vent in the front (for what I've read, placement does not matter as long as it is closer than 1/4 of the wavelength of the box tuning from the woofer, wich for me is 80 Hz, so like 1,06m something).
But, WinISD only simulates the air velocity for a rear vent, not a front vent (I think it's reserved for 4th order bandpass).
Is it ok to use the rear graph simulation for a vent that will be in the front ?
If I put the vent in the front, is the frequency response simulated (i.e for a rear vent) still revelant ?

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ssbb1fire Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 13 March 2021 Status: Offline Points: 46	Post Options Post Reply Quote ssbb1fire Report Post Thanks(0) Quote Reply Topic: Rear port and front port air velocity in WinISD Posted: 20 March 2021 at 10:00pm
	Hello, I have a question about WinISD's front port and rear port velocity. I'm simulating a woofer for a 2 way bookshlef loudspeaker and I want it vented. I'd like to put the vent in the front (for what I've read, placement does not matter as long as it is closer than 1/4 of the wavelength of the box tuning from the woofer, wich for me is 80 Hz, so like 1,06m something). But, WinISD only simulates the air velocity for a rear vent, not a front vent (I think it's reserved for 4th order bandpass). Is it ok to use the rear graph simulation for a vent that will be in the front ? If I put the vent in the front, is the frequency response simulated (i.e for a rear vent) still revelant ?

TheAmazingGanjaMan Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 27 January 2009 Location: sheffield Status: Offline Points: 148	Post Options Post Reply Quote TheAmazingGanjaMan Report Post Thanks(1) Quote Reply Posted: 21 March 2021 at 12:19am
	its referring to the port being attached to the chamber on the rear of the driver (ur bandpass assumption is correct)
	Burn Baby Burn Voice Coil Inferno

ssbb1fire Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 13 March 2021 Status: Offline Points: 46	Post Options Post Reply Quote ssbb1fire Report Post Thanks(0) Quote Reply Posted: 21 March 2021 at 2:14pm
	Thanks, but then, Is it ok to use the rear graph simulation for a vent that will be in the front ? If I put the vent in the front, is the frequency response simulated (i.e for a rear vent) still revelant ?

TheAmazingGanjaMan Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 27 January 2009 Location: sheffield Status: Offline Points: 148	Post Options Post Reply Quote TheAmazingGanjaMan Report Post Thanks(0) Quote Reply Posted: 21 March 2021 at 4:38pm
	a reflex box doesnt have a front chamber to put a port in, it is the rear chamber port not a port on the back of the box
	Burn Baby Burn Voice Coil Inferno

Xoc1 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 15 October 2012 Location: Devon UK Status: Offline Points: 397	Post Options Post Reply Quote Xoc1 Report Post Thanks(0) Quote Reply Posted: 22 March 2021 at 8:24pm
	If you want to sim the port placement you would have to use a more advanced program such as Hornresp. But for port in the front baffle WinISD should be good enough. Always best to measure impedance vs frequency on the cabinet to check the tuning is not way off.