The Moog multifilter does filter out harsh sounding things, henceforth known as coronatones.
So the documentation goes...
Channel 1 is a simple Fender/Marshall/Vox passive tonestack with treble, midrange and bass controls. Since this portion of the circuit operates at very low impedances only achievable with op-amps (and certainly much lower than a tube amp), the resistors and pot values are around 20% what you'd see in a F/M/V tonestack while the capacitors are multiplied by five to compensate. The tone controls are identical to the classic setup in frequency and behavior.
Channel 2 is a little more complex, with a Baxandall active tone control for treble and bass, a parametric midrange (which actually extends well into the bass and treble frequencies), and something called a multifilter, which is a patented Moog invention (patent #4117413, it expired today, March 30, 2020: US4117413A - Amplifier with multifilter - Google Patents) that uses a set of six fixed-frequency resonant filters to add a very unique quality to an instrument signal that is unlike any other effect. This is sometimes described by Lab Series owners as making their electric sound more like a warmer acoustic.
Ampeg uses a James tone control for treble and bass. Baxandall came along and extended the idea to a better performing active circuit. This pre adds a nice mid control. People often refer to James based tone designs as Baxandall but they aren't. Baxandall just had better marketing people, plus people like to say Baxandall. The short form, Bax, is a good name for a dog. The full Baxandall works well when he's been bad.
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