500 Hz exponential multicell horn for JBL2445

thingiverse

This is a working model of a multicell horn designed to be used 500 Hz and up with a 2" exit compression driver (e.g. JBL2445). Although it is a large project, it uses less that two spools of filament. Look at the pictures to get the idea of construction. The horn consists of 15 cells, each may need to be printed in two parts (I included also 1 part cell if you have a larger printer or want to splice yourself). The cells are printed in vase mode with at least 0.6 mm line width. Three cells are glued together front and back, then spacers are glued at the front and at the rear of the triplets, and everything is glued together. Then, the throat adaptor part must be glued at the throat. You must make sure everything is airtight, so a bit of putty and sanding is a must. Around the front edge glue the stiffeners from top, bottom and sides. First, print one of each and find where it belongs to. In total, you will need 6x TopStiffenerMid, 2x TopStiffenerSide, 2x TopStiffenerSide - mirrored print, and two of each SideStiffenerMid, SideStiffenerTopBottom and SideStiffenerTopBottom mirrored print. The driver adaptor flange is printed separately and is glued to the tubular adaptor part. The walls are too thin, so they need to be coated with a protective car body spray (e.g.Body 950) to make the walls less resonant. Casting the hollow spaces is best (polyester, epoxy, low expanding polyurethane foam or casting silicone - but be warned, I have not tried that yet). Coating with tar based paint (e.g.Body 930) is also an option if you do not mind the smell.