Loudspeakers

With the Submerge’s LPF in ‘bypass’ mode, its corrected (port/driver) bandpass is a wide 25Hz-300Hz (–6dB re. 100Hz) right down to a very narrow 18Hz-41Hz with the LPF set to the lowest 30Hz/24dB roll-off. Here latency increases from 1.3msec to 7msec and the impulse decay from 28msec to 100msec. Group delay increases from 20msec (bypass) to 34msec at 27Hz (re. 30Hz/24dB, and a mere 8msec to 20Hz) where it coincides with the port ‘tuning’, the latter otherwise providing a broad 17-71Hz contribution. Port-loaded subs can have very steep infra-bass roll-offs, with high phase distortion, but that’s not the case here – the Submerge’s active filter does not significantly steepen the expected 4th-order roll-off while also keeping latency and group delay in check. All this correlates with the ‘quick’ sound of the Submerge and its deft handling of transient detail.

For example, with a 80Hz/12dB slope, the latency is a mere 4.3msec and the in-band group delay just 8msec/20Hz (peaking at 20msec/27Hz). Also, the impulse decay time is a swift 31msec (re. –20dB) – expected, given the limited size of the driver and excellent amplifier damping [see Graph 2]. With the 12dB slope, the 30Hz, 60Hz, 80Hz and 100Hz LPF settings yield 18-67Hz, 21-87Hz, 22-105Hz and 23-125Hz bandpasses, respectively. The 4th-order (24dB/oct) slope tightens these responses to 18-41Hz, 24-73Hz, 25-90Hz and 26-113Hz, respectively [purple, orange, blue, red traces on Graph1], but note the 2-3dB increase in level... Finally, the ELF control operates below 60Hz, offering a maximum ±8dB cut/boost at 30Hz [re. 100Hz/12dB setting, grey traces, Graph 1] while distortion is a low ~0.4% (40Hz-100Hz), increasing to ~2%/20Hz (all re. 90dB SPL/1m). PM