BACK LOADED HORN
Audio reproduction began with amplification provided by a "horn" attached to the phonograph needle. This horn was folded and provided increased volume via its taper - from small tube to large horn mouth. The amplification was needed as no practical amplifiers existed.
Through the 1960's and beyond wattage became cheap. Large amplifiers and receivers often put out 100's of watts and could drive large woofers. Woofers that large however needed multiple drivers to handle the midrange and treble. Frequencies were divided into narrow bands. Music was "chopped up" and reassembled in an effort to avoid beaming. Large drivers tend to "beam" when their size is larger than the wavelength they try to reproduce. Unfortunately conventional cabinets with large woofers are needed to produce decent bass.
Later amplification became available although low in power. Large floor standing horns took the meager wattage and acoustically amplified it to produce adequate volume.
Large folded corner horns were used to provide low bass from low watts.
Fortunately an alternate method exists to produce deep bass without large woofers and avoid the "beaming effect".
The Back Loaded Horn
A back loaded horn uses the back wave of the woofer - funnels it through an air chamber - filters out the high frequencies, amplifies it through an expanding horn and doubles the low bass output.
SHINJITSU HORN SPEAKERS ADVANTAGES
Smaller cabinet size means less room placement issues
Deep bass from smaller driver decreases the "beaming effect"
No need for multiple drivers that "chop up the music"
The low frequency driver covers almost all of the critical midrange
The high frequency driver is suited to produce the highest treble
Higher quality drivers and crossovers used due to reduced cabinet costs
Most importantly - music is produced in a most natural way