Bass Trap in corner needs to be airtight ?

Hello, just a short question : (in case of John´s corner bass traps and NOT panel traps) In John´s corner Bass trap design on his homepage its written that cavity inside needs to be airtight (or more specific : air only able get in between the slats). Does this only apply to basstraps with slats on front ? Cause I also saw some pictures sometimes where people only build a frame of wood around the rigid fiberglass with no backing or closed case. For example : http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4581 Is this as same effective as a triangular closed box ? So would it be enough to build a frame out of four wooden strips (and enclosed with fabric on front and back to stop loosen fiberglass coming out) and put it diagonal on the room corners ? Or do I need to build a real closed triangular case ? Thanks in advance, Heiko[/url]

John's traps are slat absorbers, a type of tuned trap that works on the Helmholtz principle. They do need to be made airtight, so the slats and cloth and insulation behind the slats can work predictably. Without the slats, absorbent across a corner or next to a wall or ceiling does NOT need to be airtight, or even framed for that matter. See this http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4581 And this http://www.johnlsayers.com/phpBB2/viewtopic.php?t=5786 for more... Steve

Thank you, that was all I wanted to know. So now I am a bit wiser :-) Greetz, Heiko

You're welcome - So now I am a bit wiser That's how I measure my days; if I learn something, it's been a good day. Fortunately I don't have many "bad" days, since there is so much to learn... Steve