Loudspeakers

Ours is not the first review of the X3 (see https://audiogroupdenmark.com/reviews), but none seem to have addressed this speaker’s novel bass tuning. Along with the RP89 planar treble it is a key driver of the X3’s sound. While the X3 is described as a two-and-a-half-way speaker with a 2.5kHz crossover between its (upper) DCC5 bass/mid unit and planar treble, the transition to the pair of (lower) DCC5 woofers is not specified. In practice there’s a steep low-pass filter here, but the drivers are also ‘mechanically attenuated’ to prevent over-excursion at very low frequencies. This gives the impression of a bandpass centred on 87Hz, the response falling away rapidly either side [see red trace, Graph below]. The lower mode at 27Hz reflects the separate tuning of the four rear ports which, equally, reveal a proportionally lower output at 87Hz – the lower cabinet acting as a ‘dual-tuned’ bass chamber. That upper bass/mid unit, meanwhile, has a full 66Hz-1.2kHz (–6dB) range [black trace, below] that includes the strong 2kHz resonance seen on the forward response [Graph 1, see PM's Lab Report] and CSD waterfall [Graph 2, also see PM's Lab Report].

Clearly, this upper DCC5 unit is also working into the bass and is similarly attenuated to prevent over-excursion compromising its linearity in the midrange. The upper ports serve this DCC5 unit and are more broadly tuned, albeit with the Helmholtz resonance slightly offset to 101Hz, and another resonance at 700Hz visible as a port/quarterwave mode. Calculating the full diffraction-corrected bass output is complex, but reveals a strong LF peak at 85Hz [Graph 1, see PM's Lab Report] – lending the sound its impressive kick – followed by a 2nd/3rd-order roll-off and a plateau that stretches bass extension down to 25Hz (–6dB re. 200Hz). PM