Recording and Rehearsal Room for Drums

Hello everybody :-) Goal: I would like to build a (relatively) sound-proof cabin (room-in-room construction) in order to be able to play drums without disturbing my neighbours too much. I would also like to use this room for drum recording. Situation/Location: The cabin will be situated in the basement of our house (no, it's not mine -- I just live in it! ) where the walls are fortunately very massive and dense due to the fact that the house is constructed for very low energy consumption (in German it's called a "Passivhaus"). Nevertheless my neighbour is living just above in the first floor, so noise exposure is a matter. The basement floor consists of painted concrete. After reading and researching a lot about acoustic treatment and studio design I've decided to make my plans public in the hope that anybody would commentate about it. Construction Details: Length: 3,00 m (9,8 ft) Width: 2,50 m (8,2 ft) Height: 2,20m (7,2 ft) I chose this measures for having evenly spread room modes. The outside of the frames will be one ply (maybe two, if it's not enough) of gypsum board (1/2"). Inside, two walls are plywood, and the other two walls are slot resonators used as low mid and bass absorbers. I would like to use Rockwool isolation for the frames and the slot resonaters (3 1/6" or 4") The ceiling will consist of Isover SSP2 (thread about Isover) rigid mineral wool held by a simple wooden slat construction, in order to be as less reflective as possible for the high frequencies and mids. The outer side of the ceiling will also be one ply of gypsum board having a distance of 4" to the Isover SSP2. First, the floor will be the floor of the basement. If I get into trouble with subsonic noise I will build a wooden podest without any contact to the walls of the cabin. Budget: The material should not cost more than 1000$, unless it's not realizable without spending some more money. The relatively low budget is also the reason why I planned to use the cabin walls directly as absorbers. Otherweise I would have aimed to sound-proof the walls first and then build some traps for acoustic treatment inside. I have some questions yet which I hope you can answer: 1. Do you think the slat resonators are enough or shoul I add another bass absorber, maybe in the right angle corner (in opposite to the slat resonators)? 2. Does it make sense to construct the plywood walls as panel absorbers? Should I use either thicker (1") or thinner plywood (1/2")? 3. Is it better to construct the slat resonators as two hermetic boxes (one for each wall) or as one big resonator, where the back of the box consist of the two adjacent walls as you can see on the drawing. 4. What do you think about the overall design? I hope you guys can give me some advice because I have never built something like that before! I'm looking forward to your comments :) Regards Roman

Roman could you please abide by the forum rules posted in the "don't think about posting" thread. cheers john

John, sorry for my first approach -- I hope it's better now! Regards Roman

Hello everybody! I'm wondering why nobody answered my questions or commented my drawings ?!? What's wrong with my posting? Could you please answer at least one single question: Are angled slot resonators as good as "real" parallel walls (as shown in my sketch up drawings) two prevent standing waves and flatter echoes or is it better to build unparallel wooden frame walls and the put the resonators inside of them? Thanks a lot! :-) Regards Roman

Non-parallel walls do not remove standing waves, they just bend them a little (for lack of a better description). Flutter echo is removed with non-parallel and since it is mainly a high frequency issue, the slats from the helmholz trap will work fine. However, since there still will be a lot of sound hitting those reflective walls perpendicularly, there is a big chance for comb-filtering. For a pretty small room I would use 4-6" of fiberglass all around the walls and ceiling and perhaps fix some poly's in front of those walls or other type of diffusors if you want more high-end back into the room. Good luck, Dirk

hi @all! thanks for your reply. Dirk! I just started to build the wooden frame for the drum room, when I read about inside out wall design. The drum room will be situated in a corner of a basement room. Originally I planned to build a single frame wall with one leaf on each side of the frame -- so this approach would lead to a three leaf wall, with the exterior wall of the basement being the third leaf, because the distance between the drum room and the exterior wall will be about 10 cm. I will attach two drawings for better explanation: One shows the ceiling of the drum room and the basement and the other one is the floor plan of the basement with the drum room. My goal is to eliminate sound transmission between basement and first floor. Sound transmission to other rooms in the basement or outside the house is not a concern! The inside out walls are not air tight, because there is air flow to the basement room around the drum room. Does the air between the concrete wall and the gypsum layers act as a spring anyway? Is this a real inside out wall design? Is it enough to use a double layer of gypsum just for the ceiling when I'm focusing on sound proofing between basement and first floor or will the weaker walls consisting of just one outer layer of gypsum weaken the whole system? In other words: How much should I care about the double leaf walls (gypsum, OSB) not facing the external walls? Are they relevant to stop sound transmission between basement and first floor? I hope you can help me ;-) Thanks! Roman