Down to 25Hz should be good. So the 29Hz dimensions would be good (15.5 x 2.75 x 24L). Would it be better to make a backwards capital L for the port or start at the lower rear wall and go towards the front, then back towards the rear to get the full length?

The size could make noise at max output below ~33hz.

I normally just make an L shape. I picked the size so that you can use the sides of the box as 3 sides of the port. (I have not done any calculations as to port displacement. So the length could be a bit off. It is modeled at 4.5cf net.) Here is what I modeled (I didn't include the 34 hz tuning)

I added a 4th order band pass model also. Notice how it looks more like the sealed box than the ported. It should sound about the same also - just louder. Size is about the same as the ported box. If you want the specs on a bd type box just let me know.

Please under stand that this is just a tool. These models are what the box will output while sitting outside. You will get louder in a car, but the gain is not a nice even thing. If you can measure the fr of your current box then you could see better how these designs would improve the sound... or not.

Edited April 4, 201213 yr by Duane

Sure if you dont mind on the specs.

Ok this is what I have for Bandpass:

I modeled the band pass box in Hornresp. It is more advanced than WinISD. It came out about the same.... The biggest difference is that Hornresp said the box was about 8db more efficient! I think I might have messed up somewhere. But if not that would be awesome!

In the WinISD graph it shows the front and rear chambers as 1.8ft^3 each, was this modeled for two subwoofers or one occupying that enclosure? I ask as if that was for one since would take up double the space available. I am at work and have no access to it right now.

In the WinISD graph it shows the front and rear chambers as 1.8ft^3 each, was this modeled for two subwoofers or one occupying that enclosure? I ask as if that was for one since would take up double the space available. I am at work and have no access to it right now.

That is for 2. I have not tried to actually fit this design in a drawing. I think it could be a challenge to make the subs fit. I have found that splitting one of the chambers helps. (normally the ported one.) Then you can face the subs toward each other. This will need to be modeled to get the correct port size and tuning if you do.

I modeled the band pass box in Hornresp. It is more advanced than WinISD. It came out about the same.... The biggest difference is that Hornresp said the box was about 8db more efficient! I think I might have messed up somewhere. But if not that would be awesome!

I found out why Hornresp showed a higher db number. I was modeling in 1/8 space. (this is for corner loaded horns.) So the numbers were off.