Thanx for your reply, The outer shell is solid concrete,
floor, walls and ceiling.
If you look at the picture provided with former post; floor detail, you'd see: Yes,flooting floor, double decoupled, vilt and cell-isolation decoupling rulers, stuffed inbetween with homatherm flex.
Again, any considerations with respect to angels of ceiling ?
I'm not expecting any miracles, just want to exclude major low frequency problems on initial build, since they use up so much roomspace if you'd have to build bass traps, and the room is small to begin with, but tha's just a limitation i'll have to cope with.
Please, all the input is much appreciated; i have a degree in audio engineering, not in acoustics.
best regards, janek