Subwoofer drivers...

[TKoP]

Adding acoustistuff, wool batting, or fiberglass to an enclosure is great for controlling midrange reflections. But for bass where the wavelengths are massive compared to any dimension inside an enclosure, adding sound absorbing materials will lower the efficiency of the resonance mechanism of the enclosure/port. In effect it makes the enclosure behave as if it is larger and the output from the port will be reduced. That might be necessary if you go with my design and the both ports open mode, but for the ideal with one port plugged (21Hz tuning), the model assumes no acoustic dampening.

Sealed, however, often benefits from a some acoustic dampening.

I hope that helps.

Sorry, one area where I might be confused... with 2 ports open, the better alternative would be to use acoustistuff, wool batting, or fiberglass... with 1 port open, use nothing... with 0 ports open, use mass loaded vinyl or rubber sheets.

it's that first alternative I was confused.

Thanks again for the help.

 

[Flint]

Always use mass loaded vinyl or mass loaded rubber. It'll dampen the wall panels.

The acoustic material is helpful with a sealed config and may or may not be helpful with the dual port open

 

[TKoP]

Ok, obviously got confused there... found this on Amazon. Best deal I saw.

 

[Flint]

Like this and similar:
http://a.co/7bQ6oFT

This type of product is most often sold as automobile sound deadening material, but much of it has a metal foil heat shield you don't need for a speaker.

I use the heaviest per square foot I can get affordably, and just layer it up if I have a larger area to deaden.

 

[Flint]

So I plugged the info into WinISD for the dimensions, and came up with
The internal dimensions of the sub should be 22.1” x 35.37” x 13.26” (WxHxD) BEFORE we include bracing.
Assuming the ¾” MDF is actually ¾”, the external dimensions will be 23.6” x 36.87” x 14.76” BEFORE we include bracing.

Also, these were the graphs I got for two ports, 1 port and no ports
View attachment 7226 View attachment 7227 View attachment 7228 View attachment 7229

Something is wrong. I used online converters to convert the units on the Parts Express website to the units necessary for the applications I use. WinISD has some strange units (like meters squared for the area of the cone). I think one of the parameters is wrong in your driver specs in WinISD.

 

[TKoP]

Something is wrong. I used online converters to convert the units on the Parts Express website to the units necessary for the applications I use. WinISD has some strange units (like meters squared for the area of the cone). I think one of the parameters is wrong in your driver specs in WinISD.

Yeah, i had the wrong Vas number... WAY too low. Updated plots:

 

[TKoP]

That being said, I probably should have looked at the other parameters, but these looked much better to me.

 

[Flint]

That looks right

 

[Flint]

Notice the two open port option will be a little "boingy" in the 30hz range. That will enhance the deep bass feel, but hurt accuracy.