For channel 3:
- set gain to 2-3 o’clock, presence to 10 o’clock, treble to 2 o’clock, mids to 10 o’clock and bass to 9.30 o’clock, then forget about them.
- now equalize your amp with the graphic eq sliders. This is the real tone stack for you. Treble, mids and bass are preamp gain shaping tools that could really be transformed in a fixed circuit. Unfortunately the graphic eq sliders are very touchy, but you can strum a chord and make big excursions to ballpark each. Also, this will teach you what frequencies each of them is affecting at a practical, hearable level.
You should end up with 80 very high (lows are cut A LOT before this), 220 lower than that, 750 very low, 2200 and 6600 slightly above the center line.
Now work again on each one, starting from the 750, with hair-splitting movements to fine-tune your sound. Really, use your nails! 80 is your low end, 220 is your low mids but also “honk” control, 750 is your mids, 2200 is your high mids and bite control (but also harsh sizzle if too high), 6600 is your presence control.
Giulio