Why 6 dB/octave (first-order) crossover slopes?
First-order slopes are the only filter that preserves linear phase through the crossover region — but they demand drivers that behave well far outside their nominal band.
Most modern loudspeakers use steep crossover slopes — 12, 18, 24 dB/oct or more — to isolate drivers from each other. Steep slopes are usually necessary because the drivers themselves are imperfect: they have breakup modes, directivity changes, and impedance peaks that must be kept out of the audible band.
Clarisys uses 6 dB/octave (first-order) slopes. This is the gentlest possible filter, and it is only viable because the ribbon drivers are inherently well-behaved across a very wide band. The advantages are fundamental:
Phase coherence
A first-order crossover is the only slope that maintains a constant (linear) phase relationship between the drivers through the crossover region. Higher-order filters introduce phase rotation that smears the time structure of the waveform. First-order preserves it.
Transient integrity
Because the phase is preserved, a transient — a percussion attack, a plucked string — is reproduced as a single coherent event, not as a smeared sequence of driver arrivals. This is the foundation of the speed and "attack" that ribbon systems deliver.
Minimal signal path
First-order needs the fewest components: a single capacitor or a single inductor per section. Fewer parts means less insertion loss, less colouration from component dielectrics and winding resistance, and a more direct path from amplifier to ribbon.
The cost
First-order slopes overlap the drivers over a wide band, so each driver must operate cleanly well outside its nominal passband. This is exactly why the ribbons are designed with such wide, smooth, resonance-free response. Because the drivers operate in such a linear fashion, they do not introduce the errors that a steep and complex filter would otherwise have to undo.