(From Speakerlab's Technical Compendium TC-10 1979, by Pat Snyder)

"A Shortcut (pun intended)

"You will find that bass horns designed strictly to the forumula are quite long. Olson demonstrated (Reference 1, p. 114) that the horn can be shortened considerably, with little adverse effect on the bass response, by using a faster taper rate in the throat end. In addition this extends the high frequency range of the horn.

"The Speakerlab K uses a 100 hz taper rate for the first 8 inches of horn path from the throat, then a 48 hz taper rate thereafter. A line for the SK is plotted on figure 5.

"References

"1. H. F. Olson, Elements of Acoustical Engineering, 2nd Ed., Van Nostrand, New York, 1947. Out of print."