Tractrix Horn Generator

thingiverse

This generator creates tractrix-section horns, differing from spherical wave horns. Learn more about horn theory here: https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf and http://audioxpress.com/ax-supplementary-material/. Horns function as acoustic impedance matching transformers, converting high pressure-low speed to low pressure-high speed sound waves or vice versa. Note that common personal 3D printers limit printable sizes suitable for higher frequencies, even for whistles. Interestingly, low frequencies are amplified too; see http://www.thingiverse.com/thing:389700. A sample horn features a cutoff frequency of 4500Hz, an inlet inner diameter of 20mm, outer diameter of 24mm, and pipe length of 5mm, cropped to 80% with a mouth diameter of 126.5mm, a complete length of 129.9mm, and a tractrix segment length of 124.9mm. Unfortunately, the customizer struggles with this file but works fine with crop factors above 0.9.