Subwoofer Speaker Cabinet Port Tubes, 2"x2", 2 Pack | Compatible Model SAPR402G, 52.8×52mm, Bottom Grid, for PA/DJ Speaker Cabinets Subwoofer Bass Reflex Tube Box Vent

Port Tubes FunctionThe speaker diaphragm produces sound, and vibration also occurs at the rear of the speaker. After installing the port tubes, as their diameter is smaller than the speaker's, a relatively powerful sound wave rushes out of the tube. This utilizes sound waves from both the front and back of the speaker, enhancing sound quality. DimensionsOuter diameter (including Flange): 69mm / 2.72". Maximum inner diameter: 52.5mm / 2.07". Minimum inner diameter: 50mm / 1.97". Length: 52mm / 2.05". Speaker Cabinet Vent DiameterCompatible with model SAPR402G. Fits most brands of PA/DJ subwoofer bass speaker cabinet box vents. Cabinet cutout: 2". How to Choose SizeSet the cross-sectional area of the port tubes as S1, and the effective vibration area of the bass horn as S2. The optimal relationship is S1 = (0.1-0.4) S2. Port tube length LV = (1.463 * 10^7 * R^2) / (FB^2 * VB) - 1.463 * R, where: LV is the length of the port tubes; R is the opening radius of the port tubes (both in inches); FB is the tuning frequency (in Hz); VB is the volume of the sound system (in cubic inches). Package Includes2" Speaker Port Tubes - 2-Pack