Room Ratio Vs Room Volume

[Jakob De Wittig]

Hi

My friends just rented a small room in the same building where I'm building my studio. I'm gonna try helping them treat the room and then use it while I'm getting my own studio done. So here is the catch.

Dimensions
Length: 4.45 m
Width: 3.02m
Height: 3.97m

All walls are drywall and the floor are made out of wood and the room is completely empty. Before doing anything I wanna come up with a good design plan. Hopefully I have learned some stuff since my last build that didn't wen't so well

My first thought was that the length and height where to close to each other. But all dimensions pass the 5% "rule" so that's great. It is a very small room and I'm thinking that bass trapping is gonna be crucial (as always). My friends talked about lowering the ceiling and have a small upstairs for storage. Their plan was to lowering the ceiling to 2.6m.

Now I'm thinking that in a room this small. Room volume is more important than ratios, yes?? Lets say we lowered the ceiling to 2m that would theoretically get us in to Bolts area but it would be a very small room.

So what I'm proposing instead is that we keep the ceiling height. Make a false ceiling and put large acoustic hangers placed on the rooms middle 1/2 and 1/4 in both ends and then spaced all the way in between as close as possible but with enough air that everyone is hanging free. And in this way use the ceiling height for bass trapping. I would then take 45cm of the back wall and also put acoustic hangers here.

Of course first things first. The monitors are Genelec 8040. I would place them 120 cm above the floor. 85 cm from the side walls. 5-10 cm from the front wall. And place the listening position 169cm from the front wall. Is this the theoretically best placement or I'm I missing something?

I have attached a very early design sketch. With the speakers placed as described. Acoustic hangers in the ceiling and on the back wall. And super chunks in the front corners from floor to ceiling.

So the questions.

1. Is it better to keep the high ceiling for treatment?
2. If so.. Would acoustic hangers above a false ceiling be a good choice ?
3. Does this speaker placement and listening position looks right ?

All the best

Jakob

[Soundman2020]

My friends talked about lowering the ceiling and have a small upstairs for storage. Their plan was to lowering the ceiling to 2.6m.

That would reduce the room volume from53 m3 to just 34m3! Many acousticians and designers say that the minimum volume for great acoustics is about 47m3.... (It is possible to have good acoustics in less volume, yes, but it's much harder to do it...)

Now I'm thinking that in a room this small. Room volume is more important than ratios, yes??

Lets say we lowered the ceiling to 2m that would theoretically get us in to Bolts area

With the dimensions you have right now, you are already in the Bolt area! On the edge, yes, but still good enough.

So what I'm proposing instead is that we keep the ceiling height.

Yes yes yes yes!

1. Is it better to keep the high ceiling for treatment?

Yes!

2. If so.. Would acoustic hangers above a false ceiling be a good choice ?

Yes!

3. Does this speaker placement and listening position looks right ?

Yes!

The only thing I would do different, is the layout of the hangers: I would have them running in the other direction at the front and back of the room (running lengthwise), then have them running crosswise in the middle. Or if the room is wide, then do it the other way: side-to-side at the room edges, and front-to-back in the middle. Or a combination. And also, you can vary the sizes and shapes, to provide better coverage of the spectrum: Make them bigger towards the back and front, smaller in the middle of the room. OR bigger near to the walls, smaller in the middle.

Here's some photos to give you ideas:

hangers_201b_852.jpg

hangers_3.jpg

hangers_1_162.jpg

Three more things: You will need absorption panels between your speakers and the front wall, and you need to angle the speakers inwards a bit, so they are aimed at a point about 20-30cm behind the mix position. And the hangers on the rear wall: Angle the ones on the left in one direction, and the ones on the right side in the other direction.

- Stuart -

[Jakob De Wittig]

Finally all the reading and trying slowly starts to work out.

Thanks a lot Stuart. Will try to rearrange the hangers as you recommends.

..and you need to angle the speakers inwards a bit, so they are aimed at a point about 20-30cm behind the mix position.

Yes this was my plan.. Aimed with lazer pointers at a mic stand 30 cm behind the listening position

-- Jakob

[Jakob De Wittig]

I have made the first test of the completely empty room.. We have a decay time of 3sek around 500hz
The test file is here: https://www.dropbox.com/s/n2x0jgqw6zfx1 ... .mdat?dl=0

Then I have rearranged the hangers. The rear wall will be 45cm deep so I have made the hangers 60cm wide. They will be 240 cm long and hanging 10 cm over the floor.

Rear Wall.png

I have made the hangers in the ceiling bigger closer to the walls.

Front end ceiling.png

Then made them running the opposite direction in the middle.

Middle Ceiling .png

And the same as the front end in the back.

Back end Ceiling.png

Ceiling from underneath .png

I have some questions concerning density of the insulation I'm going to use.

In the paper: "Sound field characterisation and absorption measurement of wideband absorbers" from 2009 which Stuart Linked to on the sticky threat about hangers. They say that the hangers are made with a cotton waste felt with a density of around 60 kg/m3.

I can't get cotton waste felt here in Denmark. So I'm going to use mineral wool. (Rockwool) What density should I go for? Still 60kg/m3 or would 30/kgm3 be just fine ? And is it sufficient to have 5cm thick insulation glued to both sides of the fiberboards?

Then regarding the superchunks in the front corners. What density should I go for here?

Is it safe to start building and installing the hangers in the ceiling now? Then of course measure along the way to see have the room respond.

All The Best

Jakob