Loudspeakers

Unsurprisingly there are clear parallels between the O/96 [HFN Apr ’21] and the beefed-up O/Bronze. Both are rated at a high 96dB/1W/1m sensitivity, but their 13.4ohm/1kHz impedance suggests a 3.65V input while a standard 2.83V input would bring 94.9dB. In practice the O/Bronze is fractionally less sensitive than the O/96 at 92.2dB/1kHz and 91.5dB/500Hz-8kHz, but this is traded for a more uniform overall response. Again, the likely listening axis will be some 6in/15cm above the tweeter where the O/96’s upper mid/presence dip is both better handled in the O/Bronze [see Graph 1]; response errors are reduced to ±3.7dB and ±3.8dB, respectively; and pair matching remains excellent at ±0.65dB (all re. 200Hz-20kHz). Toeing the speakers slightly in or out produces a smoother response still [blue trace] albeit with a loss in vibrancy and treble bite, so subtle tweaks in positioning will clearly have a big impact on the O/Bronze’s sound.

As with the O/96, ‘blips’ in the O/Bronze’s impedance/phase spectra are linked to resonances/mistermination in the 250mm pulp bass/mid cone at 800Hz, 1.7kHz and 2.4kHz (crossover) – all are visible on both the forward response and CSD waterfall [Graph 2] although harmonic distortion is both low and more consistent than measured through the O/96 at <0.5% (re. 100Hz–10kHz, 90dB SPL). Port tuning is 3Hz higher in the O/Bronze at 46Hz but yields a similarly steep bass roll-off extending to a corrected 41Hz (–6dB re. 200Hz). Otherwise the O/Bronze remains just as ‘easy’ to drive – its 7.15ohm/186Hz minimum combining with –62° @ 71Hz / +53° @ 55Hz swings in impedance phase to bring a 3.1ohm/110Hz EPDR to bear on the partnering amplifier. PM