Even if your amp will not allow you to negatively bias a 6550 or KT88, you can significantly improve the sound through tube rolling the EL34 tube family. For NOS tubes, Mullard EL34's and Amperex Double-D getter EL34's are terrific, as are GEC KT77's and GE 6CA7 fatbottles. For new tubes I thought the JJ E34L tubes were close to the better NOS tubes in my AES Superamp. Another tube family you might want to ask the amp manufacturer about is the 6L6 family, which includes the 6L6G, 6L6GC, 5881, KT66, 350B, and EL37. There are lots of tubes to try if you like doing such a thing.
Can an EL34 tube be replaced with a KT88 or 6550?
Hi, I bought an integrated tube amp called Cheer EL34. Yeah, it was made in China so maybe not the best quality, but it seems to sound pretty good. It uses EL34, 6SN7, 6SL7, 5Z4P tubes. I was wondering, if the amp has auto biasing, would I be able to insert a KT88 or 6550 tube for the power section? I'm not sure if the socket arrangement is different. What would happen? Would the tube blow up or something?