Designing a bass reflex enclosure (2-way portable boombox) with a 2 inch side firing port. Without an additional bend in the port (which I would like to avoid) the inside end of the port will be 1.8 inches from the wall. My understanding is that distance should be greater than or equal to the ID of the port.
Is breaking this rule of thumb .2 by inches going to be problematic?
Is breaking this rule of thumb .2 by inches going to be problematic?
Since it's ideally > the pipe end correction (K) distance I don't see how there can be a fixed value without using the one for the largest area vent that will fit plus need to factor in the flare's (effective length, K), so need the width x depth + vent location and the flare's o.d., depth, so can only say that with a 1" radius (not dia.!*) pipe x 0.732 = 0.732" min. gap, it's over an inch away from 1.8" and minor tuning errors being inaudible IME, I'd be OK with it. 😉
*without dims, guessing this ROT works 'close enough' for a 2" flared?
*without dims, guessing this ROT works 'close enough' for a 2" flared?
The effective port length is about consistent cross sectional area, and the end of the port represents a dramatic change in cross section area. So I think it's fine.
But I think there are a few ways to do this that are more clever and may work better.
A 2" port seems quite large for a 4" driver. Maybe it's right for your driver choice? I will assume you've done the simulations, but based on scale alone it looks like you're building a big subwoofer.
By appearances the port tuning must be 100hz or lower? If so, why not use a straight pipe and vent it out the opposite side? No elbows required! The right port exits out the left side, and the left port out the right side? Just be sure to seal around the tubes so there is no leaking. The port exit location doesn't matter at low frequencies, especially since this looks like a pretty small unit.
I dont think the speaker will see much more than 5 to 10 watts
and be unloading pretty good around 20 watts
So velocity likely not much a issue. with smaller port
But side mounted ports is one way to do it.
Slot port sharing walls. Winisd wont calculate
be too long. K = 2.227 and winisd only goes to K=.850
for dual flare.
Use virtuix cad to adjust correction factor to higher values
or just use side mounted round ports. Since Winisd will calculate
non shared wall ports.
and be unloading pretty good around 20 watts
So velocity likely not much a issue. with smaller port
But side mounted ports is one way to do it.
Slot port sharing walls. Winisd wont calculate
be too long. K = 2.227 and winisd only goes to K=.850
for dual flare.
Use virtuix cad to adjust correction factor to higher values
or just use side mounted round ports. Since Winisd will calculate
non shared wall ports.