Air tight soffit for monitors?

I've been trying to get some information on this subject (searching all over the forum) and I can't really get anything conclusive. Simple question, and I welcome any help: I'm soffit mounting my active near-field monitors. Apart from the vent holes for cooling, is it necessary to make the rest of the chamber where the monitor sits air tight? I'm building my soffits along the lines of the attached pic, but the question of "air tightness" is unresolved. Thanks! gb

Airtight isn't necessary - the main thing is that you don't have gaps in the plane of the front baffle, either the part that's the face of your speaker or the baffle EXTENSION that is the face of the soffit. These two planes need to be flush with each other, but you can have up to about 1/2" between the speaker box and the soffit construction - but, once the speakers are in place you should fill any gaps with insulation, keeping it even with the face of the speaker and the face of the soffit. Otherwise, you can get high frequency diffraction around the edge of the speaker box and into the cavity of the soffit - this will put a dip in the speaker response so the crack needs to be filled to avoid this. Using insulation just helps you keep from coupling the baffle extension (the face of the soffit) to the speaker box, so that the soffit doesn't become a passive radiator for the speaker. The end result should be that you have only a narrow gap around the speaker box, and that the front face of the speaker box is even with the front face of the soffit... Steve

Thanks very much Steve--that actually clears up a lot of questions!

found this pic to describe my question. i scoured the site again, but couldn't find any posts/pics to answer. 1. does the baffle/speaker extension need to be COMPLETELY flat?? it IS flush with the speaker, but can it be paneling similar to the pic below? the panels themselves are only 3/8" thick, so the grooves are probably only 1/8" deep, maybe even 1/16". i'd like to use the same wood i'm using on my walls for the baffles. for looks, but i don't want to compensate sound, obviously. thanks, Mike

i hope this works. it looks SICK!