Loudspeakers

If the forward response, with its presence band dip [Graph 1], emphasised midrange and 23kHz treble peak - made all the more irregular with the grille in place [blue trace] - look familiar then that's because we saw the same in the Concept 50 and earlier Concept 500 . While there is consistency in Q Acoustics' voicing of its larger, two-way MTM style speakers, the more affordable 5050 is also more relaxed in its specification. For example, the response errors here are a wider ±4.8dB and ±4.2dB, respectively, versus the Concept 50's tighter ±3.5dB and ±3.7dB. That said, pair matching remains an excellent 0.7dB (200Hz-20kHz) except for an inconsequential blip of 2dB at 16.4kHz. And, again, the reinforced midband pushes up sensitivity to 92.2dB/1kHz even if the broadband (500Hz-8kHz) figure of 90.0dB falls below the rated 91.8dB. THD is a little higher at ~0.9% through the bass in the 5050 (re. 90dB SPL/1m) but remains very low at sub-0.1% in the midrange.

Cabinet and driver resonances [CSD waterfall, Graph 2] are slightly 'livelier' in this model than the Concept 50 and there's a mode at 810Hz escaping the port, the latter tuned to 32Hz to boost bass extension down to a diffraction-corrected 41Hz (-6dB re. 200Hz). However, your amplifier may pay a price for the 5050's sensitivity and good bass in facing a fairly tough load. While the impedance minimum is nothing out of the ordinary at 3.0ohm/482Hz, this is joined by a swing in phase angle of -63o/

78Hz which precipitates a minimum EPDR of 1.44ohm/670Hz but also a sub-2ohm EPDR from 88Hz-280Hz and 490Hz-975Hz. It's the latter that will drain the amp of puff... PM

Above: Cabinet Is Not Quite As Inert As The Concept 50'S And Modes In The C3 Driver Appear At 7-10Khz

Above: Response inc. nearfield summed drivers/port [green], freefield corrected to 1m at 2.83V [yellow], ultrasonic [pink]. Left, black; right, red; grille, blue

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