FabFilter Pro‑Q 2 Help
When you move the mouse cursor near an EQ band in the display, a parameter value display pops up showing the current parameter values for the band.
Click and hold the solo button (with the headphones icon) to enter solo mode for the current EQ band. The other EQ bands will dim, just like the yellow overall curve. Simply drag the solo button horizontally to change the frequency of the band, or vertically to adjust the solo listening level.
In solo mode, you don't hear the effect of the EQ band itself, but instead you will hear the part of the frequency spectrum that is being affected by that band. Of course, the frequency range depends on the frequency and Q settings, and is visualized in the display as well.
When using solo mode with Low Cut or High Cut bands, you will hear the frequencies that are being cut away instead of the frequencies that pass, which helps you to determine whether you are cutting the right frequencies.
Generally, solo mode aims to expose the parts of the incoming audio that matter to the current EQ band, but that you can't hear just by listening to the regular EQ sound.