i know there is a brand of door that is "the one" to get for sound-lock
purposes.
There are a few. Wenger is one. Google "acoustic doors" and you'll find more.
I used plain ol' solid core slabs with Zero seals around the perimiters in my
studio and they work fine. Do they have the same attenuation as the heavy
Wenger modesl? No. Do I wish there was better sepatration? Sometimes, but
rarely. On occasion I need more isolation. Luckily we have two booths
separated from the main room by airlocks. In those instances, the solid core
doors in conjunction with the airlocks provide plenty of isolation.
Joe Egan
EMP
Colchester, VT
www.eganmedia.com