9.5 Important ISIS Recommendations

Built as an identical pair of transducers, ISIS retains one difference between right and left channels that is noteworthy. Very low frequency bass coupling with the room is selectable in one of two orientations. Even serial numbers should be placed as the left channel, while odd serial numbers are designated as the right. This is the optimal set-up for most situations, producing the widest stage spread. In certain extremely wide listening rooms, or rooms with many apertures to other spaces, there may be a diminishment of low frequency impact at the center of the soundstage in the above orientation. In such cases, extra center-stage bass impact may be increased by reversing the speaker orientation so that the even serial number is right and the odd serial number left. This subtle increase in center impact will of course be at the expense of stage width. In almost all set-ups there is an excess of low frequency energy at the center of the listening room that should be diffused with a high bandwidth pressure absorber such as the DAAD from Acustica Applicata7. Therefore it is extremely unlikely that the left/right orientation of the Isis channels would be other than the first recommended scenario.

Whether your amplifier is a voltage source or a current source design, the Isis will demand that the amplifier and the interface between amplifier and loudspeaker work at optimum levels. For this reason a high-energy transfer speaker cable is essential. We will not recommend any specific brand of wire interface, however the characteristics of any cabling should include:

∙In phase current and voltage delivery throughout the passband, extending below 20Hz.

∙Equal octave to octave energy response throughout the passband.

∙No excessive imbalance between inherent cable capacitance/inductance.

∙Significant high frequency extension in order to minimize passband ripple effects.

The inherent linearity of the ISIS power response, frequency response and transient response will be compromised by a speaker cable that does not meet the above requirements.

7 For more information about Acustica Applicata, consult their web site: http://www.acusticaapplicata.com/

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