Paul C
Super Member
The damping I was suggesting was to kill the higher in phase/out of phase response variations that result from the direct radiation of the driver reinforcing or cancelling the radiation from the mouth of the horn or transmission line, rather than reflections and other funnies that happen only inside the horn.
The damping material acts as a low pass filter, that is, allowing the bass frequencies under 80 hz - 100 hz to pass through with little if any effect, while effectivily killing the higher frequencies. So, in the upper bass to midrange, only the direct radiation of the driver is heard. In the bass frequencies, only the region that is reinforced, that is, where the direct radiation of the driver, and the backwave coming through the horn, where those are both in phase, are not affected. There, the bass is reinforced where it would normally be falling off.
This is sort of the same effect as a port, but over a wider range of frequencies.
And a rear loaded (as opposed to a normal front loaded horn) can be more closely compared to a transmission line design, but the line is a horn.
Now, here's the cool thing... unlike cutting and gluing a wood cabinet, that once it is made, you either use it or discard it and start over, damping can be added AND removed. It can be adjusted easily and quickly, and relatively cheaply. This is strictly a "try and see", like adding seasoning. You are the judge.
And your room response would also affect the overall sound, so for a particular rear loaded horn or transmission line, one can't say, "Put X cubic feet of dacron fiberfill right here." What may be good in one room might not be so good in another. Or you may want boomier bass, if a fan of Rap, Hip-Hop, R&B, etc. Or damp the line more for a more natural sound for listening to real music.
