Originally Posted by bossa nolyx
500 Hz makes roundabout 0.7m wavelength. This board is very "uninteresting" for sound waves of 500Hz...
Here are the specs and the description of the box by the manufacturer, (unfortunately in German...)
Die vor dem Tieftonsystem befindliche vertikale Metallplatte ist funktionell eine akustische Frequenzweiche zur Absorption der Frequenzen oberhalb 500 Hz (-3 dB pro Oktave).
We already had a discussion about those speakers
I admit, I don't have a clue about loudspeakers and audio arrangement.
Just can tell you what the manufacturer writes and what my ears tell me.