Panel Absorber


A panel Absorber is created when you place a sheet of plywood or fibreboard, with insulation glued to the back of it, over an air cavity. The panel will have a resonate frequency of its own, tap it and you will hear it. When it is placed over a sealed cavity, and insulation is attached to the back, everytime it hears its own note it resonates and the air in the cavity resonates and the insulation absorbs the resonance, hence absorbing the frequency! It is important to note that here we have an absorber that reflects the high frequencies and attenuates the low. With the hangers all that exposed insulation absorbs the high frequencies as well so the panel absorber has a place in the studio. The two factors determining the frequency of absorption are:

  • The mass or density of the panel.

  • The depth of the air cavity, i.e. depth of the sealed timber frame.

Calculate frequency of absorption of the Panel Absorber

Filling the cavity with fibreglass or mineral wool tends to lower the resonant frequency by up to 50 per cent as well as doubling the effectiveness of the trap. It also lowers the Q of the trap so that it is effective over a wider frequency range. A typical panel-type trap is effective for frequencies around one octave either side of the centre frequency, which at least has the advantage that you don't have to be absolutely accurate to get results.


Calculate Frequency of absorption


Panel mass [kg/m2]
Depth [cm]

Frequency of absorption Hz
recommended width cm
recommended length cm
Area m2

Calculate depth of the Panel Absorber>/



Panel mass [kg/m2]
Frequency of absorption [Hz]

Depth cm
recommended width cm
recommended length cm
Area m2

Calculate mass of the Panel


Frequency of absorption [Hz]
Depth cm

Panel mass [kg/m2]
recommended width cm
recommended length cm
Area m2



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