No distortion takes place here yet, only amplification and equalization. Set the Input Gain to a level appropriate for your instrument or track. Low Cut (which determines the cut-off frequency of the 6 dB/octave high-pass filter) should typically be turned to the right (maximum frequency = maximum cut) for electric guitar operation (unless a Low Cut has already been applied).
These are switched in series, and completely identical. You can switch them on and off. They have a 3-band equalizer with adjustable cut-off frequencies, and a Drive dial that determines the gain and the resulting distortion. The equalizer is "passive", which means that when Low, Mid, and High are in maximum position, no alteration of the sound takes place (flat frequency response, 0 dB gain).
Again, you have the same type of 3-band equalizer at your disposal, an Output level dial (mind the level on the VU-meter in the Cabinets section!), and an extra Low Cut dial, which should typically be in or close to the 12 o'clock position when using the Cabinets section (which boosts low frequencies considerably).
It says "Cabinets", because there are two almost identical sections in
parallel here, which you can balance with the Mix dial. You can switch
this section off (but be honest: would you want to?). The sound of both
sections is determined by their Prox (proximity) and Fdb (feedback)
dials. Typically, you would have Prox1, Fdb1 and Fdb2 turned all the way
to the right, Prox2 somewhere around 12 o'clock position. Mix after taste.
NB: in some positions, you can hear a slight high frequency "ringing". This is normal, and deliberate.
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