THREE SISTERS — FILTER VISUALIZER

LOW CENTRE HIGH ALL (sum)
Crossover partitions the spectrum: LOW = 24 dB/oct lowpass, HIGH = 24 dB/oct highpass, CENTRE = the band between. Sum is approximately flat at low Q.

Formant = three bandpass peaks. SPAN spreads LOW and HIGH; CENTRE stays at FREQ.

QUALITY past ~70% approaches self-oscillation. CCW-of-noon notch behavior is not modelled.