Celestion System 6000 loudspeaker system Page 3
Coloration levels were low, with no perceptible box effects, and just a mild, cone-type, "nasal" thickening in the upper mid. A hint of "sibilance" was also present in the treble. Taken overall, however, the treble was very fine, with high resolution, transparency, and neutrality, free from grain or "zizz." Only if the subwoofer level were set too high—to make an excessively weighty low end, for example—would some lower-mid muddling occur, this due to excessive driver overlap in the 100Hz region. With levels correctly set, the bass possessed a natural, fast, and open "slam," with good tune-playing ability. The bass controller was deleted to check its effect on the mid and treble. It was possible, when using the most costly supporting electronics, to fault the controller very slightly on treble purity and transparency, as well as demonstrating a small impairment in stereo depth. The latter loss was more than restored by the System 6000, due to the reduced SL600 workload, this resulting from diverting the large bass excursions required to the subwoofer.
Interestingly, the Quad ESL-63 would be a potential alternative to the SL600 for use with the 6000 woofer (footnote 1). A pair of '63s were tested, and the Celestion's dipole bass matched that of the Quad very well, providing a powerfully clean low end, improved mid clarity, and allowing the Quad to play several dB louder on wide-band program. Moreover, the Quad '63 sounded good at the increased height conferred by the 6000 platform, resulting in a generously "tall" speaker effect.
These two remarkable speakers represent a challenge to the increasing performance standards being set by large panel speakers, matching the best of them in terms of both bass power and extension, while at the same time conceding little in terms of coloration levels. In fact, both the KEF and the Celestion beat a number of the panel models in such fundamental areas as tonal balance and response uniformity.
The 6000 system and the R107 are refined systems, with no obvious flaws or rough edges. In no way do they represent "first prototypes"—their designers are not going to have second thoughts during the next six or twelve months!
With its distinctive—if not downright odd—appearance, the System 6000 offers a more costly solution to the same problem, one with additional refinements in terms of room bass alignment, transparency, and treble subtlety, but with a substantial reduction in maximum sound level attainable. If genuinely high sound levels are required, then it must be said that the 6000 will not suit rooms of greater than 120m3 volume. In my room, however, with its near ideal proportions and moderate 80m3 dimensions, the 6000 fit like a glove, delivering the best big-speaker bass yet, and with a clear enhancement of the SL600 performance.
The System 6000 has suffered from greater compromises in engineering than the KEF, this partly due to the incorporation of the low-sensitivity SL600. Conversely, this is also one of its major strengths: when powered up in this three-way system, the '600 easily stretches beyond its previously known limits to generate a satisfyingly dynamic and balanced sound. Competitive though the R107 is, the Celestion 6000 also scores a hit, but on a different target, this one significantly nearer the heart of the high-end market.
Given the 6000's performance, it seems apparent that Celestion has also produced one of the finest, least colored subwoofers around. Tests with the Quad ESL-63 were most encouraging; it is also a natural partner for other high-quality dipole systems of limited bass power. It will also work well with smaller and cheaper systems, but its $3300 cost does not really justify such partnerships.
Footnote 1: Quad's Peter Walker always used to decry efforts to marry his loudspeakers to moving-coil subwoofers on the grounds that the overlap between an omnidirectional subwoofer and a dipole loudspeaker was inherently unsatisfactory.—John Atkinson