Tapped Horn Project https://fatproduction.webs.com/apps/photos/ Tapped Horn Project Tapped Horn 30Hz tuning Box is a 4 'x 3' x 23" monster of a bass box. Quarter wavelength is 8.3 feet giving a tuning freq. of 30Hz. https://fatproduction.webs.com/apps/photos/photo?photoID=197312470 197312470