Medium-sized concert venue

[Neutrino]

Dear all,

this is not exactly a studio build, but I still hope to get some help here.

I have been approached by a friend who asked me if I could help him treating a middle-sized vaulted cellar that shall be used as a concert venue. It shall be suitable both for small classical ensembles like string quartets (un-amplified) as well as jazz/pop combos (amplified). I have a decent understanding of small room acoustics and have recently built my own studio control room. I thought this might be a good opportunity to extend my knowledge to middle-sized/large room acoustics.

The dimensions of the room (rough SketchUp file attached) are LxWxH = 35m x 6,5m x 3,4m. However the ceiling is vaulted since this is a very old vine cellar. Walls are about ~1m thickness. All surfaces are hard: concrete or stone on the floor and brick walls/ceiling. See (animated?) picture below.

Gewölbe_2_959x372.jpg

RoughPlan_noCeiling.jpg

Unfortunately, I don't have good pictures of the room yet, since it is a construction site with poor lighting and no windows. Behind the stage there are two openings in the front wall which are for the air conditioning. They cannot be closed. On one of the side walls there are two doors that connect the room with another similar one which as far as I understand will be used for catering. Reasonable sound isolation towards this room shall be provided at some point.

The budget is currently open, but as a working assumption, I would start with something like 10k Euro for the acoustic treatment.

The main problems from my perspective are the following
- Front-to rear reflections: due to the tunnel-shape of the room it has a pretty long echo
- The focusing effect of the vaulted ceiling causes a strong coloration of the sound. I was there during a choir reversal and a had the impression of overly strong low mid frequencies
- The double use of the room (unamplified vs. amplified) calls for some extend of flexible acoustics: Longer reverb times for unamplified use and shorter reverb times for amplified use

I believe it would be to advantageous to design the rear wall highly absorbtive (except for the stairs, of course), e.g. 50 cm of rock wool.
However, it is also planned to install a glass wall in the rear of the room (next to the stairs as seen in the picture), but no final decision has been taken yet, i.e. it might be possible to install the wall at an angle or only cover part of the rear wall, such that there is still some room for absorption.

For the front wall (behind the stage), I would also think that thick absorbers would be beneficial, although maybe only the corners should be treated to avoid overdamping. Classical musicians are used to hear a lot of reflected sound, I think. Some additional panels could be added if needed for amplified music.

The side walls could be treated with acoustic panels or hard, angled surfaces to redirect the sound towards the back of the room and mitigate the effect of parallel walls.

I would be highly interested in your opinions on these ideas. Moreover, I am unsure what the best way would be to deal with the focusing effect of the vaulted ceiling. Any suggestions are welcome.


Thank you!

EDIT: attached previously linked image, added more details and note on budget