Hi imperyal, that's a nice design to my amateur eyes!
I have a simple though tedious method for getting the internal volume. (I'd love to hear a better way!)
Manually draw the simple shape of the airspace minus the port. Ignore the braces for now.
Select all, make group.
Select the group.
(At least in sketchup make 2017) Entity Info will show a volume for it:
The same idea can be used to get the volume of your real braces. They need to be a fully enclosed 3d shape, just make a group (or component) out of it:
Write them down, subtract the brace space from the air space and you're done!
...I'm guessing you could do it all directly in sketchup - by intersecting the shapes - so you could get the final volume directly, but I've never tried it.
Last edited:
My only direct feedback is: if you're getting the port lengths directly from winISD they may be a bit longer than necessary / it could be tuned lower than you expected, for the reason that winISD only models the end correction for a port away from any walls. (It has a box to change it, but it has no effect). My apologies but I don't know how to manually calculate the difference.
Attachments
I friend recommended me to check Air velocity on the port using BassBox Pro 6.
I did that and the air velocity is around 21m/s (on WinISD is 19m/s).
But I noticed another difference, the signal...
In WinISD arround 1800W is the power required to achieve xmax.
In BassBox Pro 6 a 2700W signal is needed for that.
It is a big difference... What's going on here?
I did that and the air velocity is around 21m/s (on WinISD is 19m/s).
But I noticed another difference, the signal...
In WinISD arround 1800W is the power required to achieve xmax.
In BassBox Pro 6 a 2700W signal is needed for that.
It is a big difference... What's going on here?
Nice driver 
Just because this is DIY and we can over engineer, have you considered using CDL bracing?
- https://patents.google.com/patent/US20060231327A1/en
Just because this is DIY and we can over engineer, have you considered using CDL bracing?
- https://patents.google.com/patent/US20060231327A1/en
I think I will need some help....
I did the test to find the tunning freq of the box, and found that it is around 33Hz. I found this using the Tone Gen App (iPhone) and observing/feeling the woofer movement. At 33Hz it moves the lest.
But my box is not sealed yet... it has air leaks. Does this void the test? Do I need to fully seal the box to get and accurate result? I suspect yes....
I can use some duct tape to seal it temporarily for the test and adjustment of the port length.
I did the test to find the tunning freq of the box, and found that it is around 33Hz. I found this using the Tone Gen App (iPhone) and observing/feeling the woofer movement. At 33Hz it moves the lest.
But my box is not sealed yet... it has air leaks. Does this void the test? Do I need to fully seal the box to get and accurate result? I suspect yes....
I can use some duct tape to seal it temporarily for the test and adjustment of the port length.
Did you build the ports at the exact length that your simulations suggested?
When a slot port uses one of the cabinet walls it acts as if the port is longer, and I believe the amount is 1/2 the height of the port. So when building a cab if you shorten the ports by that amount the tuning should come out at about the intended tuning.
When a slot port uses one of the cabinet walls it acts as if the port is longer, and I believe the amount is 1/2 the height of the port. So when building a cab if you shorten the ports by that amount the tuning should come out at about the intended tuning.