all pass filter for back loaded horns

[U130421]

Frequencies bellow 120hz are in opposite phase in back loaded horns . Has anyone tried an all pass filter as one shown to put back in phase ?

 

[planet10]

In a well-designed horn the output of the mouth is in-phase and (n+1)/2 wavelengths behind what is coming out the front. As the frequencies go lower, the phase moves

You could try a filter but i think it would need to be more complex than what you have shown.

dave

 

[U130421]

For 50hz to be in phase with the front wave, the length of the horn must be 3meters .
May be someone has measured the overall phase response at low frequencies <250hz. Personally I don't have a back loaded horn to try it out , but the filter must be very simple not to de nature the signal .

 

[planet10]

Given that at the turnover (typically 200-300 Hz) we have the signal (1+n)/2 wavelengths behind (driven by an 180° out-of-phase impetuous, thus in phase). As we go down in frequency the wavelengths get longer, but take the same time to transit the horn, thus becoming fewer wavelengths behind, but slowly moves out of phase… How many time the phase rotates thru 360° depends on how long the horn is and what n above is.

dave