direct listening comparisons, tractrix, JMMLC, oblate spheroid

JoshK said:
I need to calculate it but it is going to be bigger than 16" at the mouth. I know this because the 16" mouth radius is what Dr. Geddes's Summas were that were used down to 900hz. The Horn Theory part 2 article in AudioXpress gave a formula for the effective loading Fc.

to cross a tractrix or JMMLC at 800hz, a 400hz Horn is needed. Since i have already a tractrix horn ready here, with 20", i will only need to turn a JMMLC and OS. i will do it after finish a big midbass horn. Then i will post my impressions here.