Abstract: A loudspeaker system has a housing forming a first horn, and two low-mid range speakers mounted in the horn throat with front faces in opposition and rear faces in loading and detuning chambers formed by the housing. A third, high-mid speaker, of the same size and type is mounted to a rear of a second horn, integral with a phase plug which has a fourth, high frequency speaker coaxially mounted in a front end to form a high-mid/high frequency speaker assembly which spans the mouth of the first horn in coaxial loading relation with the front faces of the low-mid speakers to balance the rear loading. The rear face of the cone of the third speaker is sealed against the front pressure wave generated by the rear speakers. Both sealing portions and the phase plug are sufficiently close to the cone to avoid resonance therebetween at an upper limit of the operating frequency of the third speaker.