hi, sorry i know this thread is old. i try to read all i can about the Hartsfield speaker to understand it the best i cani collected a lot of pictures from various forums on internet. one thing id like to know is if there is any stuffing/pading in the horn path itself, i saw in some cases on original cabinets some visible pading on the front cover where there is a V that direct the wave on the sides....am i wrong ? visible when the woofer itself is removed looking up front id say...(see picture)I made some prototypes of this speaker and found that there are very nasty resonances at 100hz and 200hz.horn lenght and calculation suggest a close match to a 50hz wavelenght...so basic harmonics should match.... pading in there must help i guess.any improvements you made on yours ? you mentioned it didnt sounded as good as you wanted....thanks....