A common type of tweeter will do the job. Make sure netting is being put in front of the LDS (Long Distance Speaker) otherwise you will find dead birds inside. The edges of the tweeter will hold perfectly onto the inside wall of the PVC tube (4" type). To make it more secured, you may add some epoxy glue at all 4 edges of the tweeters. The length of the PVC depends how far you want the sound to travel, 4 feet is sufficient. At even
more than 45 dg angle water still can't sip into the tweeter unless you put it direct (90 dg) facing the sky. Between the 4 edges of the tweeter there are gaps which the water could sip thru so that the tweeter is always not affected by water. With such low cost of making, I am sure you all could own more than one for your bird farm, make sure not too loud otherwise any complain I am not responsible for it .
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