RE specs with displacement or not?

[tmcilroy 10+ year member]

RE's webiste shows the optimal box for a SE12 ported is 2.0 cf @ 33hz. Would this mean I want 2.0 net or 2.0 before the sub is installed?

Click to read more...

 

[tmcilroy 10+ year member]

Also the RE calculator suggests I use 2 8" ports but the subwoofertools calculator shows 1 9" and 1 25" port. They are similar sizes but the ports would look a lot different. They are also both near 33hz, which would be better to use?

 

[Tempe 10+ year member]

Before/after sub blah blah blah. You need 2 net cubes of volume. If you built your enclosure as a single sealed chamber (no sub, port, or bracing), the inside volume would be your gross volume. Here we go:

Net volume + port displacement + sub displacement + bracing displacement = gross volume.

I did a box design for someone last night. His gross volume was about 1.77 cubes, his port displacement was 0.25 cube, sub displacement was 0.1 cube, and bracing was 0.15 cube. This left him with 1.25 cubes, which coincided magically with his net volume of 1.25 cubes.

You want about 24-32 inches of port area for that sub... depending on how much power you plan on it seeing.

T

 

[tmcilroy 10+ year member]

I do understand how you find the gross and net volumes but I was wondering what the RE spec 2.0cf @ 33hz was 2.0cf with or without the sub installed in the box.

 

[tmcilroy 10+ year member]

Basically when the calculator asks for the overall NET volume, do I want it to be 2.0 or 2.15?

 

[Tempe 10+ year member]

2.0 is what the subwoofer sees. If you took the subwoofer out of the box it would become a 2.15 cube box.

T