In this video, we'll talk about whether a 12AV7 makes a good substitution for a 12AY7, and also check out several high end tubes through this 1956 Fender 5E6 Tweed Bassman - an Amperex Bugle Boy 12ax7, a Mullard 12ax7 (RCA labeled), a GE 12ax7, and an RCA 7025. Ever wondered how these tubes might compare? Here's your chance to find out.