Loudspeakers

The breakup mode of the Teonex compression driver, or its interaction with the horn throat, is clearly illustrated just outside of the audioband [pink shaded area, Graph 1] at 22kHz, rising some +15dB above the mean midband output of the HDI-3800. The CSD waterfall [Graph 2] suggests this is short-lived but it also reveals a broader mode/reflection around the 1.8kHz crossover frequency at the limit of the topmost 200mm alloy-coned woofer (–6dB bandwidth of 45Hz-1.4Hz). The midband emphasis between 1-3kHz is visible on the forward response [yellow shaded area, Graph 1], which looks smoother thereafter without the diffraction of the grilles in place [blue trace], but the high ±8.4dB and ±8.1dB response errors are due to the lift at 20kHz. The errors fall to a more respectable ±2.8dB/±2.5dB between 200Hz-10kHz while the pair matching remains tight at 1.3dB.

Sensitivity, rated at 92dB, is still very generous at 89.0dB, both at 1kHz or averaged between 500Hz-8kHz. However, as anticipated from JBL's '4ohm nominal' specification, this has not only been achieved by the surfeit of reflex-loaded woofers and horn-loaded top but also by a moderately current-hungry load. The latter drops to a minimum of 4.4ohm/129Hz (sub-8ohm from 75Hz-2.08kHz and with an ultrasonic dip to 3.4ohm/30kHz) and with maximum phase angles of –60°/66Hz/16.2ohm, getting tougher in the midband at +55°/2.1kHz/8.1ohm. The paralleled pair of lower woofers operate over a narrower 48-410Hz (–6dB), rolling off steeply below 72Hz, but the output of this trio, with the low 25Hz port(s) tuning, delivers a bass extension of 35Hz [–6dB re. 200Hz; green shaded area, Graph 1]. PM