Acoutic room treatment

[MikeFromNorway]

I'd like you're opinions on roof treatment in a acousticly deacent living room.
Size 8x5meters, where 4x5m is the designated music area. With listening postion around 3,5m from front wall.

I want to treat half the rooms ceiling. Its divided by construction into +/-120cm blocks, running 4m, in total 4.
Planning on removing the old ceiling material, install spots and white acoustic matts from Rockfon/Glava or similar.
I have around 20cm space before running into the wooden floor in the attic.

So the q-s are.

1) How much of the ceiling should I treat?
2) What do i choose? the Rockfon comes in similar material in thickness from 15mm-50mm. The absorbtion caracteristics are similar, but the room-room absorbtion is better the thicker the absorbtion material is (which is not important/not an issue for me).
3) Do I leave the space above the insulation plates empty?

Example:

Rockfon Blanka® dB 35| Ekstra lydabsorpsjon og lydisolering

Skap fleksible kontorlandskaper. Akustikkhimlinger kombinerer lydisolering rom til rom med god lydabsorpsjon. 25 mm kjerne av steinull | Rockfon himlingsplater.

www.rockfon.no

 

[MikeFromNorway]

These are the beforementioned "roof sections".

 

[Inner Space]

Hi Mike - you have the opportunity here to tackle two different issues at the same time.

1) Ceiling reflections, which are always better eliminated. I would group all the absorbent panels directly over the 4mx5m listening area. Use 50mm - the thicker the better, always.

2) If you can fill the 20cm space under the attic floor with fluffy fiberglass, packed fairly tight, above a thin skin of drywall or plywood, you will get a fairly good bass-trap effect, to damp the vertical mode in the room.

Both are really worth doing, and shouldn't ruin the look of your lovely room.

 

[MikeFromNorway]

Hi Mike - you have the opportunity here to tackle two different issues at the same time.

1) Ceiling reflections, which are always better eliminated. I would group all the absorbent panels directly over the 4mx5m listening area. Use 50mm - the thicker the better, always.

2) If you can fill the 20cm space under the attic floor with fluffy fiberglass, packed fairly tight, above a thin skin of drywall or plywood, you will get a fairly good bass-trap effect, to damp the vertical mode in the room.

Both are really worth doing, and shouldn't ruin the look of your lovely room.

Thank you for the quick and good response.
To be clear, you suggest, layers from the room upwards to the floor of the attic:
50mm rockfon (rockwool/packed fiberglass absorber)
5mm plywood
150mm fiberglass

 

[Inner Space]

Thank you for the quick and good response.
To be clear, you suggest, layers from the room upwards to the floor of the attic:
50mm rockfon (rockwool/packed fiberglass absorber)
5mm plywood
150mm fiberglass

Yes, exactly, with the 50mm absorbers grouped over the listening position. Together, that will give a good result, while being visually neat and acceptable. Good luck!

 

[GalZohar]

As far as I'm aware, if you want good audio results then you should use treatment that is designed for audio.
You should also measure to see which aspects of the audio are the most problematic in your room and make sure whatever treatment you want to apply is suitable for reducing those problems. For example, thin panels will do nothing to low frequency issues, which are a a problem in most/all untreated (and even treated) rooms.

 

[MikeFromNorway]

As far as I'm aware, if you want good audio results then you should use treatment that is designed for audio.
You should also measure to see which aspects of the audio are the most problematic in your room and make sure whatever treatment you want to apply is suitable for reducing those problems. For example, thin panels will do nothing to low frequency issues, which are a a problem in most/all untreated (and even treated) rooms.

Yes, agree. That is why I will go for something like this (see link). The prices are a lot more sensible then products sold by specialized audio shops.

https://p-cdn.rockfon.com/siteassets/commerce/no/tiles/documents/documentation/produktdatablad-himlingsplater-og-veggabsorbenter/no-tile-datasheet-rockfon-blanka-db46_d_06_20216.pdf?f=20220209033227&_ga=2.175325026.1339966949.1644483490-264226041.1644483490

 

[MikeFromNorway]

Wit price in NOK

Account Suspended

 

[Bjorn]

50mm treatment of traditional absorbers is very bandlimited, meaning you will alter the frequency content. Especially when using a good number of those, one can generally end up with a overly damped highs and no proper treatment for low mids and bass. Of course, if one is using only a few panels, the altering of the spectral content will be minimized.

Measurements posted by products are also quite misleading as they are based on a diffuse field which doesn't exit in small room and many show NRC numbers which is an average for the speech frequencies only.

The below graph basically what you achieve with 50mm traditional absorbers in a small room, except that highs will will not be dampened as well as the graph shows since the products have a fairly hard surface and thus are quite reflective in parts of the treble area.

For a great result one would like to have an even absorption with high coefficiency down to the Schroeder frequency. But obviously one has to weigh that against WAF and aesthetics as is it requires thicker panels.

 

[Dj7675]

These are the beforementioned "roof sections".
View attachment 185609

I would first try to identify what needs fixed. Best way to do that is measuring with REW or something like that.

 

[GalZohar]

Yes, agree. That is why I will go for something like this (see link). The prices are a lot more sensible then products sold by specialized audio shops.

https://p-cdn.rockfon.com/siteassets/commerce/no/tiles/documents/documentation/produktdatablad-himlingsplater-og-veggabsorbenter/no-tile-datasheet-rockfon-blanka-db46_d_06_20216.pdf?f=20220209033227&_ga=2.175325026.1339966949.1644483490-264226041.1644483490

But they don't do anything with the bass, which is probably the most important (although you should measure and see). Panels that handle lower frequencies would be much thicker. But you'll be probably be much happier with the result.

 

[Inner Space]

But they don't do anything with the bass, which is probably the most important (although you should measure and see). Panels that handle lower frequencies would be much thicker. But you'll be probably be much happier with the result.

Bass will be helped by his in-ceiling treatment - read the posts. The whole ceiling void will be a decent trap. The thread is about the ceiling only.

 

[MikeFromNorway]

Bass will be helped by his in-ceiling treatment - read the posts. The whole ceiling void will be a decent trap. The thread is about the ceiling only.

Thanks.
I’ll defenitly do some measurements but since We’re painting the ceiling and putting in spots anyway i thought it would be a good idea with some treatment. Which will be:

50mm rockfon
5mm plywood
150-200mm finerglass
25mm wood (the old floor of the attic)
2400mm air (the attic)

I am hoping this will give me some improvements. And yes i will dsp the system after to make adjustments.

 

[DonH56]

I suspended 4" (~100 mm) panels at the tip of a triangle with one base point at the speakers and the other at the main listening position (MLP). I do have panels directly overhead, but the path I was concerned about was from the speaker, up to the ceiling, and then bouncing back to (at) the listener. The puts the ceiling panels a little forward of the MLP.

How many, how thick, etc. is partly personal preference and partly dependent upon the modes in your room and their relation to the MLP. Start with a little and add as needed is the usual advice. I rather prefer a dead'ish room so went overboard right off the bat.

FWIWFM - Don

Edit: I don't quite follow your stackup -- is the plywood behind the first 50 mm of absorption? Leaving it open with an air gap will make it more effective as an absorber. These absorbers work by changing velocity (sound waves) to heat in the panel, and the velocity right at a boundary is about zero (depending on the stiffness of the panel) because it stops the sound waves as they reflect back into the room. Leaving an air gap behind the panels means the entire depth acts as an absorber vs. losing some efficacy right at the boundary (wall or ceiling).