Straight horn kick bins

You will be amazed how good a well designed folded horn can sound even up in the lower midrange. I too started out thinking only a straight horn was a "pure" horn, but really the faultiness of a folded horn is merely the product of all the combined faults in the folding throughout the horn path.

I've recently tested a prototype using two 12s on two horns with 3 90-degree bends within 1/2 wavelength (longitudinal) of my intended upper roll-off, the bends being less than 1/4 (cross section) in dimensions. 80-800hz. I was surprised how well defined the upper region was without any processing applied. The lower part needed some FIR/EQ due to the small mouth of a single unit.

If aiming for 60/70 from a straight horn, a bandpass/compression chamber solves a few things; it allows a phase bung for well distributed compression for extended high frequencies. It can be used as a diffraction device to control dispersion and wave propagation. It can me rendered to obtain a desired flare rate without surpassing the desired mouth/throat/length dimensions. Designing a true horn with phasebung can be troublesome but really is an interesting journey due to the above "tools".