Hello Denis.
If You open up the cavity cover, You will find tiny blue capacitors soldered between the volume and tone pots. These set the frequency barrier of the treble-bleed (of the tone pots).
They usually have the capacitance of 0.022 micro-Farads on Les Pauls. I stayed with these values, however, I replaced the ceramic capacitors with paper-in-oil ones. They made the guitar a bit less bright, more throaty sounding. Those big ones, with the "AMPOHM" brand.
Cheers... Bence