When the QUADRO was developed, the primary objective was to produce a loudspeaker with a very high sensitivity rating because the trend in recent times has been a retrograde one towards high-end tube amplifiers. However, these are often restricted to very low outputs of only a few watts. There are plenty of loudspeaker constructions which promise extremely high volume levels with only one watt but, on closer examination, are seen to produce that level only at medium and high frequencies. Extending the high sensitivity level to include low frequencies is indeed a challenge. To achieve that aim, it is crucial to include a very large diaphragm area which, in turn, requires a large sized cabinet if one wants decent bass volumes.
The generously sized enclosed QUADRO cabinet provides sufficient space for four of the excellent B 200 - 6 OHM full-range loudspeakers to ensure that, even at the lower end of the bass frequency range, there is plenty of cone excursion. The drivers are closely bunched one above the other, which provides for an excellent radiation pattern: a broad angle in the horizontal plane and a relatively tightly bundled beam to top and bottom. To prevent the bundling effect becoming too strong in the vertical, all the drivers are powered in parallel in the bass frequencies and, as the frequency increases, the B 200 - 6 OHM 's are phased out one after another so that, at very high frequencies, only the second driver from the bottom is working. The slightly tilted front baffle means that this full-range loudspeaker is then aimed directly at ear height, assuming one is seated at least 3 metres from the speakers.
Anyone with experience of the sound properties produced by the SOLO or SOLITUDE speakers will have a fairly clear idea of the clarity of soundproduced by the QUADRO. These qualities are, however, boosted by the fact that the air in the room is set in motion by a large diaphragm area but that force is hardly aimed at the floor or ceiling at all. A noticeable feature of the QUADRO are its clarity and analytical qualities, while, at the same time, not becoming obtrusive. The QUADRO may not be able to match the extremely deep bass output levels of the SOLITUDE, for example, but that is in fact a positive feature in rooms that are not so large because the reverberating room resonance frequencies are not stimulated at all. However, the physically tangible kick-bass effect, a feature expected from musicians' speakers, can indeed be produced if the amplifier is powerful enough. In addition, the QUADRO shows its strengths in the faithful reproduction of voices and recordings of large orchestras. It is fair to say, then that this is a good, all-round high-end loudspeaker.