# Drywall construction for 45Hz?



## Neomius (Dec 21, 2013)

Hi, 

im planing my new home theather. Initial measurments shows that I have a Room mode of 45 Hz caused by the lengt of my room.

Using the standard formula for panel absorbers and the weight of the plasterboards I am going to use gives me

Deept of wall: 20 cm
Mass/m2: 9KG/m2

This gives me a absorbtion peek at ~45Hz. BUT, there is (at least two) other aspekts that is not coverd.

1: You want to use a thin layer of dampning inside the trap. This affects the Q factor and modifies the center absorbtion frequency. Is there anyone who know how this changes?

2: I plan to use screws to attach them to the wood frame. How does this affect? Attaching them more loosly would probably change the behaivure, right? And if each panel is 30x30 cm or 300x300cm would also affect, right?

Is there any formulas that are more specific or is there anyone who has made measurements of this? I have a feeling that I will build a big panel absorber which just ads to my problem.

Bonus question: Is it possible to build a panel absorber and place it right behind my projector screen? (it's not an audiotransparant screen)

Thanks in advance!
//Neomius


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## phazewolf (Feb 5, 2012)

The more insulation you have behind the panel the wider range the trap will work and in exchange the peak that it will trap will be less.

To work the panel needs to be able to flex.


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## bpape (Sep 14, 2006)

To do 45hz, assuming you're doing a sealed membrane type of absorber, the depth of the cavity behind will need to be much thicker than would fit behind a screen.


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