Openings in Infinite Baffle

[seedlings]

I've only spent a few hours here as a guest, then signed up. I'm new to IB world, but not new to subwoofer building in general.

Short: Does the 'baffle' separating the 'infinite' back side from the front listening area have to be continuous and air tight? How much leniency is allowed for an opening between the two rooms?

Long:
When we finished the basement, there was the dilemma about finishing the ceiling with drywall or suspended ceiling due to access requirements for plumbing, etc. We decided to simply flat black spray all the joists, pipes, wiring, sub-floor, insulation... everything... then put up 'recessed' lighting. This was very cost effective and I really like the look. But.

Now in consideration of a pair of drivers in IB... this means that there is no continuous, sealed wall partition between the theater room and the adjacent storage. There is drywall up to the joists, but you can reach your arm up over the wall, through the joists to the next room... the 'baffle' is not continuous through the whole wall. So the back wave and the front wave meet at the top of the wall.

Even if this project doesn't get off the ground, this ibsubwoofer site is a lot of fun plus a learning exercise.


Thanks,
CHAD

Attachments:

[gworrel]

You would almost certainly want to seal off the opening using pieces of plywood or osb. How hard could that be? I used the Linkwitz dipole spreadsheet to answer a similar question for myself recently. If the minimum distance to the opening is 20 feet, the bass response is not reduced until you get down to 10Hz. (If I remember correctly.)

If the distance is less than 10 feet, then you will not get good response down in the 20Hz and lower region you want. You can download Linkwitz's SPL_max1.xls spreadsheet and try out your numbers yourself.

[seedlings]

Thank you for tour answer- it's helpful. I've read where some have used the basement as the enclosure, and I figure there are surely openings like stairwells between the two. I see that 8' distance is much different than a 20+ foot distance.

Much obliged.

CHAD

[gworrel]

In plugging the gaps, you would not need anything particularly strong, but just reasonably airtight. Something like extruded polystyrene (XPS) in 1.5" or 2" thickness painted black and sealed with canned spray foam would be easy to cut and fit into place. It is fairly inexpensive and solid enough to do the job I would think. I used it to insulate the rim joist in my basement with individual pieces cut and sealed into place.

[ThomasW]

Need to rotate the drivers so that one isn't firig directly into the floor

[seedlings]

Dec 13, 2012 16:49:51 GMT -7 ThomasW said:

Need to rotate the drivers so that one isn't firig directly into the floor

Yes. (It was an artistic rendering )

CHAD