The port length is not the problem, it reproduce only low frequencies. It's just a problem of correct response curve. It can be often difficult to have good balance between deep/round bass and strong kick: if you make a strong kick, it can be at the expense of the bass and vice versa. There are some effects of mask.
This type of horn can sound good up to 500Hz, but you must eq it correctly. So use measurement mic, analyser, reduce all peaks in the response curve, try to locate the frequency you hear as honk and reduce it.
This type of horn can sound good up to 500Hz, but you must eq it correctly. So use measurement mic, analyser, reduce all peaks in the response curve, try to locate the frequency you hear as honk and reduce it.