Ceiling design

Hi, Right now I started to renew my mixing room. I am gonna soffit mount the speakers (JBL 4420), behind I will do superchunks (60cm). On the sidewalls I have angled broadband absorbers, the rear wall will have a diffusor (schroeder design) and in the corner also superchunks. My question: The plan is to build a ceiling, starting above the speakers (2,40m) rising up to 3,50m. I want to build a fabric coated frame as ceiling. Should I use hangers behind the fabric or is a 10cm insulation glaswool enough? Can somebody explain a "compression ceiling" and its benefits? thanks in advance, Jonathan

"compression ceilings" typically are high in the front, dip in the middle and high at the back or just start high in the front and lower in the back. the idea is to preserve energy from the speakers but in many cases doesn't work in smaller rooms and just ends up messing with the response and the RFZ. one way around this is to make the "compression ceiling" a set of slats and openings for bass trapping in which case it's not really a compression ceiling any more... one of the more common approaches is the "expansion ceiling" where it starts low in the front and is higher in the back. another option is a cloud or series of clouds to shape the space and leave room overhead for bass trapping. here's an example of the latter download/file.php?id=35086&mode=view a lot of times, you'll see false ceilings with various bits on them to do the same thing. John Sayers has a number of rooms where slats and so on are embedded into the ceiling to preserve and diffuse but giving the impression of a solid ceiling. one example John recently posted was a "compression" ceiling design but used bass trapping ports around the edges so it is more of a LF wave guide effect while preserving high frequency response.

Thanks Gullfo. Thats exactly what I had before. But now I want to close the ceiling completly, so I will build a fabric covered frame as a expansion ceiling. Above of it I will put hangers or just 10cm glaswool. The former design was not damped enough in the highs. thanks!

G, The 'compression ceiling' was one of Tom Hidley's early designs. This type of ceiling caused many early reflections and comb filtering. You are on the right track - Absorptive ceilings in critical mix rooms are definitely the way to go. Cheers, John