small tube in 4th order bandpass

[palesha]

I came across one subwoofer box with 4th order bandpass. Normally half box is sealed and in the other half tuned port is fixed. But in this box they have additionally put one .75" tube between the two chambers inside the box. What can be reason?
MP

 

[kelticwizard]

There are bandpass boxes that have a sealed chamber behind the woofer, a vented chamber in front.

There are bandppass boxes that both behind and in front of the woofer they have a chamber vented to the outside.

And finally, they have bandpass boxes with a chamber behind the woofer that is vented to the chamber in front of the woofer. The front chamber is itself vented to the outside.

I will look for some free software to predict the response. BoxModel used to have free software for this arrangement, but appraently no longer does.

One of our own members, F4ier, has written Subwoofer Simulator which will predict the behavior of this sort of box, along with all the others.

I will try to dig up the link.

Here it is:
http://www.geocities.com/f4ier/speaker.htm

 

[palesha]

Here is the picture of sub. Comments about design required from the experts. this is a commercial design.

 

[kelticwizard]

That's the bandpass box I was talking about, all right. Subwoofer Simulator will enable you to grapgh the response of that type of box.