I am not sure if this is a bass amp question or an electric bass question. So I will ask it hear as people are likely more knowledgeable in the amp area than in the bass area -- the issue seems to be electronic. I have a Cort Curbow -- one of the classic ones from the 90's -- and when I played it through my Peavey Pro Bass 500, certain notes would just disappear from the mix of the band. For example, if I hit a D on the G string, it was like I hadn't played it at all. It was like the amp couldn't pick that frequency up. Can anyone explain why this might have happened?