Input trim knob (or fader) is a “one knob” internal gain staging control that link automatically the input and the output gain stages with an inverse law. In this way you can control the amount of non-linear distortion without constantly need to adjust the input and output gains.
Note that trim input is different from a standard input gain control due to the inverted linked output gain stage, which always ensures that whatever gain change is introduced at the plug-in input, the output level is automatically compensated, so that there is no perceived level change.
When a positive value is selected, the signal entering in the plug-in is brought up by the set amount in dB and the plug-in emulation will operate at a higher internal level. This will result in higher harmonic distortion levels. Contrary to this, negative values will result in a lower internal operational levels and lower harmonic distortion levels.
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