I bought a Marshall YJM100 this July and it's great. As far as Im concerned I'm the 3d owner of this amp so It's obviously not new. Anyway I'm concerned about the normal sensetivity input for the high treble channel. It's basicly no treble, or tone for that matter and it's kind of a bummer cause I can't get that Plexi tone I was after. I'm using my Boss ME-70 to boost the singal and then it sounds okay but I shouldn't have to do that..
So my question is.. Is my amp broken or will this be fixed by changing valves? The owner before me didn't change valves and I don't know if the owner before that did eather. (This is a problem that must have occurred from the previous owner since I bought it like this)
Regarding your YJM100 we would recommend that you have it checked by an engineer as it should not be lacking treble, it may be something straight forward as a replacement pre amp valve.