JBL HDI-3800 Loudspeaker Around The Horn

Around The Horn

If there's one brand synonymous with horn-loaded loudspeakers then that's JBL, not least because of its footprint in the pro-audio/sound reinforcement industry where horns help achieve the high sensitivities and constant directivity necessary for controlled audience coverage. Continued research into optimum horn profiles, and the compression drivers at their throat, have also kept JBL at the forefront of domestic implementations, most notably with the flagship Project Everest DD67000 [HFN Aug '14]. The horn-loaded tweeter featured in the HDI-3800 is a little less sophisticated although its claimed range – down to 1.8kHz – remains ambitious.

The driver is based on JBL's iconic 2410 pro-series model, although the alloy diaphragm is replaced here with a softer (Teonex) dome that improves its efficiency by compressing the small volume of air trapped immediately in front. A concentric, exponential phase plug is placed just ahead of the dome in an effort to provide multiple, equal-length pathways for the sound waves to navigate out to the throat of the flared horn. In practice it's impossible to avoid unequal pathlengths out of the horn, just as non-ideal impedance matching with the air at the horn mouth causes reflections and resonance, but JBL is well versed in optimising what is inevitably an imperfect solution. PM

Harman International Industries
Supplied by: Harman Luxury Audio Group, Cambs
01223 203200