Im going to be building a 2cuft after displacement ported box for my 12" Brahma Mark ll. Its going to be tuned to 25hz. The port area is going to be 42" (14"x2") and 53.33" long.
My question is with having the port are 14"x2" is that going to cause port noise? Thanks
Replies (1)
swez on 10/8/2006 04:16:49
Probably not as the port has a large area to vent air and keep turbulance and port air velocityshould be pretty low here.
Just be sure to use an "infrasonic filter" here. The greater the slope of this filter, (18-24 dB/oct.) the better. If you can employ a HPF filter at ~30 Hz., even a 12dB/oct. slope should work out OK here.
That vent seems undually long/large for this size box. Just ran some calculations and a 4" dia. round port need only be 25" long for this Vb and 25 Hz., PTF. A pair of 4.0" x 12.5" long round ports would be fine here and take up less airspace, (port displacements) and allow for a smaller and much lighter enclosure too.
Care to double check your vent dimensions again? Adjusting the aspect ratio of this vent, might show the need for a shorter vent tube and a smaller enclosure too.
Swez
My question is with having the port are 14"x2" is that going to cause port noise? Thanks
Replies (1)
swez on 10/8/2006 04:16:49
Probably not as the port has a large area to vent air and keep turbulance and port air velocityshould be pretty low here.
Just be sure to use an "infrasonic filter" here. The greater the slope of this filter, (18-24 dB/oct.) the better. If you can employ a HPF filter at ~30 Hz., even a 12dB/oct. slope should work out OK here.
That vent seems undually long/large for this size box. Just ran some calculations and a 4" dia. round port need only be 25" long for this Vb and 25 Hz., PTF. A pair of 4.0" x 12.5" long round ports would be fine here and take up less airspace, (port displacements) and allow for a smaller and much lighter enclosure too.
Care to double check your vent dimensions again? Adjusting the aspect ratio of this vent, might show the need for a shorter vent tube and a smaller enclosure too.
Swez
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