What material to use for acoustic panels

[Musicmaker]

Hello everybody! I need some advice where to place DIY acoustic panels, I have an idea on material to a point but not sure what else would be required or recommend I plan on using 100kg/M3 Rockwool as it must be fire resistant.



I would also like advice on what material I should use for the corners of the room and how big should they be for the corners if possible.

The image above is the room plan with measurements.

Thank you

[Sam Spoons]

RW3 is 70kg/m3 and is usually considered optimum. WRT positioning, it will depend on where you have your monitors and listening position (and where you plan to sit/stand when recording acoustic instruments or voices).

The basic principle for a mix room is to start with the primary mirror points on the side walls, the back wall, the ceiling and behind/between the speakers. Bass traps are best placed in corners and the bigger the better.

This article Hugh wrote about his own room goes into detail.

https://www.soundonsound.com/techniques ... sound-good

[Musicmaker]

RW3 is 70kg/m3 and is usually considered optimum.

I have watched videos on youtube and someone recomend to use 100kg/m3 on the wall panels.i am not sure if that will be too much? whats your thjoughts guys?

Bass traps are best placed in corners and the bigger the better.

If i will put 140kg/m3 in the corners, will thatr be perfect material? What about density on the ceiling?

[James Perrett]

RW3 is 70kg/m3 and is usually considered optimum.

I have watched videos on youtube and someone recomend to use 100kg/m3 on the wall panels.i am not sure if that will be too much? whats your thjoughts guys?

100kg/m3 is probably too dense for general use as it may be less effective at high frequencies. Save it for bass traps - but put a layer of 60kg/m3 Rockwool/Earthwool on the front of the bass traps to absorb the high frequencies. I'd use 60kg/m3 for most of your panels and space them away from the wall/ceiling to make them more effective.

[Hugh Robjohns]

Different densities affect absorption at different frequencies. As a general rule of thumb, higher densities (80kg/m3 and up) are more effective at very low frequencies but can actually make high frequency reflection worse, while lower densities 60-80kg/m3 are better at mid and high frequencies.

But the overall panel thickness also matters a lot, as well as the type of panel you're making and its position relative to boundary surfaces.

For general broadband absorbers, I'd aim for 60kg/m3 mineral wool which is effective over a pretty wide bandwidth. Large bass traps can use more dense material, or better still, a combination of dense and less dense...

As a good, accessible reference to the subject I'd recommend reading Home Recording Studio: Build It Like the Pros by Rod Gervais as a good introduction to what to do... and not do when it comes to DIY acoustic treatment.



https://www.amazon.co.uk/Home-Recording ... b_title_bk

[Musicmaker]

Save it for bass traps - but put a layer of 60kg/m3 Rockwool/Earthwool on the front of the bass traps to absorb the high frequencies.

If i understand correctly, you would use 2 layers? 100kg/m3 at the back and another layer 60kg/m3 at the front of the bass trap? Does there have to be anything between layers?

I'd use 60kg/m3 for most of your panels and space them away from the wall/ceiling to make them more effective.

How much space would you normally have? And same density 60kg/m3 goes on the ceiling?

[Hugh Robjohns]

There are no one-size-fits all answers.

That's why I recommended the book. There are lots of 'it depends' caveats.

You need to understand how acoustic treatment works to be able to design and implement it effectively. Get the design and/or placement wrong, and you'll waste a lot of time, effort and money...

In simple terms, the panel spacing from the boundary depends on the thickness of the panel and the frequency range you're trying to affect. The aim is to get the majority of the absorption into the 1/4 wavelength range of the frequencies you're hoping to absorb.

As for the variable density idea, you don't need to put anything between layers, but you may improve efficiency if you do. There are pros and cons. Some designs put aluminium foil or a thin plastic membrane between the layers. Some use three layers (light, heavy, light) rather than two....

For mirror point broadband absorption, 60kg/m3 is fine, two inches thick as a minimum, four inches is better, spaced the same distance from the wall. The ceiling cloud can be the same, but the spacing below the ceiling will probably be larger just to get the cloud into a more effective overhead position.

Bass traps are a lot more complex and their design will depend on what problematic frequencies you need to deal with, which will depend on the room dimensions and construction.