BOX PLAN] SINGLE 15" Subwoofer Triangle Ported - YouTube
BUILD THIS! 15" two-way PA cabinet design - Celestion
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Yamaha CW115V Passive 15-Inch PA Subwoofer
Amazon.com: Sound Town 2-Pack 15" 1600 Watts Powered Subwoofers with Speaker Outputs, DJ PA Pro Audio Sub with 4-inch Voice Coil (METIS-15SPW2.1-Pair) : Musical Instruments