I have a wierd problem i usually use a high gain setting on my 50 watt rectoverb head and redbear 4x12 cab on the extreme setting or vintage setting and sometimes i get a really sweet sound out of it and no feedback if my hand is muting the strings but also sometimes instead of this really sweet high gain sound i get like an inbetween of a highgain and crunch type sound, its hard to explain but it just sounds much worse and adding gain or eq-ing doesnt seem to help. Any advice?
So you dont change anything, this just happens? Could be a bad cable or connection somewhere. Check all your cables and patch leads, try running straight from guitar to amp, see if that fixes it. If its not cables or pedals, it could be a bad tube (most likely preamp from what you've described)