I own a Randall RG75DG3 and it has lost it's low end ever since it got fixed....twice. it got fixed because the transformer blew out twice. i have a PRS SE Singlecut trem guitar that goes into EVH Phase90 then a Mark tremonti wah then the amp. i usually practice without the pedals. the clean is perfectly fine. it has more low end then the overdrive channel. it hasn't lost the low end completely, it's still there. its just that the amp isn't as resonant anymore if you know what i mean. when i first got it i usuall had the bass on 6 or 7 because there was so much of it. now i have it on ten all the time and it doesnt vibrate the room like it used to. also another problem with the amp is the contour control. it doesnt make a difference to the sound from 1.5 to 10 but below 1.5 it loses volume and goes into "metallica land."
why do you think this has happened?
Preamp valve is probably on its last legs, and needs a replacement. Valve replacements aren't a difficult thing and if you buy the right one its a simple slot in- slot out arrangement.
so you think its the preamp valve? ok ill try that out. the amp is hybrid tho sowould it be able to make that much of a difference?
turns out its not the tube. i had it changed and still sounds the same. same brand and model of tube too.