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Uxcell Speaker Sound-Absorbing Polyester Audio Insulation DIY HIFI Replacement 15.75 x39.37 White
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Speaker sound-absorbing cotton is installed in the speaker to absorb standing wave from the low frequency of the cabinet. After installing the sound-absorbing cotton will make the bass clearer and strong. The acoustic propagation will make space larger. The amount of sound absorption cotton in a box should be tested actually. When the bass is smeared install more sound-absorbing cotton. Otherwise reduce cotton.
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