It is made from a length of 8 inch plastic waterpipe, around 3 feet long. I drilled a bunch of evenly spaced holes in it. Then I pushed the plastic horns through the holes in the pipe. I used finishing nails as pins to push through the ends of the horns to lock them in. The horns are just kids toy megaphone things you can buy off the net. Then I spray painted the whole thing yellow. It used to look a lot better but it has been up for a few years already. I just never got around to recording it until now. There are two Universal Security Instruments 12V DC sirens inside. They are exactly the same, but one takes a split second longer to wind up than the other. That makes it sound almost two tone (basically out of phase). You would not get that effect if you spun both choppers on the same motor. The sound resonates inside the waterpipe and then gets forced out the horns. The horns really do make it louder.
Great idea , Plastic Pipe , for a siren case
I wonder how much wider you can buy it than 8" .
Could be another possible way to make a cover for Fed. #2
without a housing & a lot cheeper than Federals price of about $315.00
I don't know how much it costs for the pipe. I just go to a construction site and ask them for the scrap pieces left over. They have all different diameters. I know they have 10". They also had a plastic pipe the size of a manhole cover diameter. Plastic is great because it doesn't rust and it is light weight. I might make a mini model 2 type the same way using a Federal Model 28. You can also go to a hardware store and buy a chimney cap. They make good tops for siren covers.