31 203 Amplifier Filters: 32 "200' 227 Amplifier Low-Pass Filter: 33 254 State-variable, 12 dB/octave Butterworth or 24 dB/octave 34 290 Linkwitz-Riley with continuously variable cutoff frequency 35 337 selection from 50 - 500 Hz (defeatable). 36 392 Infrasonic Fitter: 37 426 24 dB/octave Bu