practice room ground plan geometry

Hi everybody, I play in a band, the music is mostly rock. Unfortunately we now have to give up our practice room and buld a new practice room in the basement of my house. We decide to build a room in room. To avoid standing waves, we considered not to build the walls parallel. Unfortunately, the space is not large and with absorbers on the walls, it would be pretty tight. Now we have to decide wheather it is worth to effort building the sloping walls. I have drawn two ground plans. What plan would you implement? Ceiling height is only 2.03 meters. room 9.25 x 22.49 feet. Thanks for your time Best regards Chris

Hi Chris. welcome. Please read the forum rules for posting (click here). You seem to be missing a couple of things! :)

To avoid standing waves, we considered not to build the walls parallel.

You cannot avoid standing waves by splaying the walls: that is for avoiding flutter echo. ALL rooms have standing waves, more correctly called "modes", simply due to the dimensions. A room with non-parallel walls will have no axial modes, but will still have plenty of tangential modes and oblique modes. A mode is simply a path around the room that a wave can follow and arrive back at it's starting point in phase with itself. There is nothing you can do to prevent modes: they are a natural consequence of just having walls around the room.

Unfortunately, the space is not large and with absorbers on the walls, it would be pretty tight.

You will need absorption on the walls: there's no doubt about that. It is a small room, so it will need lots of bass trapping.

What plan would you implement?

The one that provides the greatest room volume. But also check your ratio, to see if it is good or not. It is very important to stay away from bad room ratios, and get reasonably close to one of the many good ones. Your room is rectangular, so you can use any of the "room mode calculators" that you find on-line. Of course, you can only do that if you do NOT splay the walls: as soon as you splay them, the room becomes non-rectangular and the simple mode calculators are no longer applicable: the only method for predicting modal response in non-rectangular rooms is with FEM/FEA.

Now we have to decide wheather it is worth to effort building the sloping walls.

Not worth it, no. If you suspect that flutter echo will be an issue then it might be worth while, in which case the minimum useful splay angle is 12°, but it does not eliminate modes: it just moves them to a different frequency, which cannot be predicted with the normal mode calculators. - Stuart -

Thank you for your detailed reply. I think then we will give up the idea splaying the walls and work with absorption on the walls.