Eldartford,Back loaded horns are used in many full range driver systems using lowther AER fostex drivers, others. They are more of a hybrid of TL BR and horn in a folded pathway cabinet.But a few are true full back loaded horns but even they need some tuning. When you used a fullrange you need to absold some of the back wave to prevent a peak in frequincy responce. This is what the poster is refering too.
