Sonab OA-12 cabinet architecture

[JoelRiehl]

Can someone describe the path of the back wave from the mid-woofer to the port tube? I assume the back of the mid-woofer is open to the inside of the cabinet, and not sealed like the midrange in the OA-116. The cutaway views always have the top of the port tube blocked from view by the acoustic insulation. Are there better plan and section drawings of the internal structure out there somewhere?

[STDI!]

In OA116 there is a sealed box for the midrange at the top of the speaker. The woofer at the bottom of the speaker use the port and is of course not sealed.
Since the 6,5" in OA12 is both mid and woofer there is no sealed box.

Your question reminds me of a discussion about how the mineral wool is supposed to be placed. You find the discussion here: http://www.faktiskt.se/modules.php?name ... &list=full . In Swedish but I hope you can translate it with google translate. Obviously the mineral wool has been placed in different ways when produced.

[Russ]

I found this picture,if it`s any help.

http://www.minhembio.com/bilder/hq/?pic_id=422539.jpg

The picture was found in the thread STDI mentioned.

[STDI!]

That picture shows the strip of mineral wool around the walls of the "woofer compartment". In my OA12, and obviously also in many others, it was placed in the other compartment, around the bass port. And that is also how the original sketch show it.
I don't know if it makes any difference in sound. But either way it must not cover the bass port.

[JoelRiehl]

Hey, thanks for the great information and quick reply. I'll take the time to run the thread through the translator and look further. I notice the divider in the top chamber now. It looks like the back wave is directed at least as far as the middle chamber, then up around the bass tube before being let in through the top and out.