Click here to purchase the entire book in PDF format. Ported Cabinet (aka Bass Reflex) You can achieve a lower low cutoff frequency in a sealed cabinet if you cut a hole in it - the location is up to you (although, obviously, different locations will have different effects...) Figure 6.189: INSERT CAPTION If you match the cabinet resonance, which is determined by the volume of the cabinet and the diameter and length of the hole (look up Helmholtz resonators in the Acoustics section), with the speaker driver resonance properly (NOTE: Could someone explain to me what a ``properly matched'' cabinet and driver resonance means?), you can get a lower low frequency cutoff than a sealed cabinet, but the low frequencies now roll off at a slope of 24 dB/octave.