Acoustic foam v standard high density foam for ISO box

[TheFevered]

Hi gearslutz,

We are building a MDF iso box to throw our cabs in for a bit of lower noise recording, and we have hit the point where we have to decide which foam to go with to deaden the inside.

We have been given 2 options:

Specialist acoustic foam, density index of 32 - $180
Standard foam, density index of 35 - $100

So basically the standard foam is cheaper and has a higher density than the acoustic foam, and the people at the place seem to think that they would have a similar level of absorption. We thought you guys may know better.

We were also considering just getting a piece of acoustic foam to sit on the wall of the iso box that the cab faces, and then the cheaper foam for the other surfaces, just to save some dollars.

What say you gearslutz?

[fabricaudio]

How thick is the mdf?

The foam inside is used more for the reflections inside the cab not for isolation.


Nikolas

[TheFevered]

The MDF is 1 inch thick. We want to use the foam primarily to cut down on reflections.

[fabricaudio]

Originally Posted by TheFevered

The MDF is 1 inch thick. We want to use the foam primarily to cut down on reflections.

You can use rockwool like they do in the acoustic panels. Foam is more expensive and it works only in high frequencies.


Try to make the box as heavy as you can in order to isolate more and use some rubber support for the amps.

Nikolas

[TheFevered]

Thanks for the advice. I'll look into rubber supports. Is the idea of that to prevent some of the low frequencies escaping? And I'll also look into rockwool. The box itself weighs a hell of a lot. Once it is properly sealed it should do a decent job.

[fabricaudio]

Originally Posted by TheFevered

Thanks for the advice. I'll look into rubber supports. Is the idea of that to prevent some of the low frequencies escaping? And I'll also look into rockwool. The box itself weighs a hell of a lot. Once it is properly sealed it should do a decent job.

You are practically making a ''room in room'' construction but in smaller scale. The less attached surfaces the better the isolation. The rockwool also will offer a more broadband reduce of reflections and the mic recording will have less low end compared with having foam.

I am in the process of making some isoboxes too in the next months but probably i will make them from steel and probably they will be heavy enough (around 150 kg).

You can post some photos of the process


Nikolas

[Glenn Kuras]

Originally Posted by fabricaudio

You can use rockwool like they do in the acoustic panels. Foam is more expensive and it works only in high frequencies.


Try to make the box as heavy as you can in order to isolate more and use some rubber support for the amps.

Nikolas

Agreed,

If you do go with the foam then go with what has lab numbers. No need to risk it.