Can an EL34 tube be replaced with a KT88 or 6550?

Thanks for the info, Arthur. I tried looking up info, but all i found was the site www.audiofi.com. It has a contact link, but there is no email or phone listed. I thought maybe the KT88 amps were more expensive mainly due to the higher cost in the tubes. It appeared like the input sockets all looked the same, so I was hoping I could do some tube rolling with various tube types. Alas, it is not possible.

Thanks,
Clinton

All EL34's don't sound alike, not by a long shot, so even if you can't use 6550's and KT88's, you can get some tubes which will sound significantly different. You will still need an auto bias curcuit or the ability to re-bias the amp with the new tubes. Ditto small tubes except you don't need to re-bias for them. Good luck......

Depends on the topology/design of the amp.

Thanks for the advice. I think i'll just get a quad of either fat body Electro Harmonix EL34, Mullard EL34 or JJ Telsa...heck maybe i should just get em all and see what characteristics they have. My amp does have auto bias, as I took it to a repair shop to get some knobs fixed, and the guy said it was auto bias. Plus there are no bias holes anywhere on the top or back of it. Woo hoo for auto bias!

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.