Welcome Dmitry,
Awesome looking Epic! There are one or two people on the forum that have 93 Epics, and the very earliest ones have the serial # in the control cavity, but they're also from 93.
About the contols, I think you may be confusing the controls - either that, or someone changed the electronics setup ...
If you have the bass standing up and you're looking at the front, then the top left knob (closest to the bridge pickup) is master volume. Bottom left is pan, which has a center detent at the halfway mark.
Top right is bass, bottom left (closest to the plug) is treble: bass and treble offer a little bit of cut and some more boost. I am told that on later Epics the bass and treble controls also have the center detent at the point where you go from cut to boost.
Hope it helps ...
Adriaan