EL34 in a 6550 amp?


I just got a Jolida 502 int. that uses 6550/KT88 tubes, but I was wondering if I could use EL34 tubes as well?
koestner
Some amps that take EL 34s and can also accomodate KT-88s KT-90s KT77s and of course the 6CA7. Some will tell you that even the auto biased amps require some manual biasing to do this. It certainly makes intuitive sense that different bias voltages to the screens and plates for each tube would be required for them to operate optimally.
None the less I use KT-88s in my Jadis DA 60 which originally came to me used with EL 34s. I am not certain what it was built with however. I was informed KT 88s would work. They sound fabulous and are my favorite in this amp (GL reissues).
My thinking though was that transformers were more or less tube specific but I could just be running them at a lower plate voltage or something?? than is optimal. The bias is automatic and hard to set manually I have been told.
The only tube I have not rolled into this pin out is the KT-66. I am afraid to try that but understand that this whole family of power tubes was derived from that one.
Please correct me if I am wrong.
I don't have it yet. It will be delivered on Tuesday. Plus I don't even know which Jolida I got it from (Shenda or Maryland). The amp was designed for 6550, but they say a KT88 can be used as well. EL34 are supposed to be smoother so I was wondering if they would work also
I own a 502B. 6550 and KT88s are interchangeable (have done that) but, to the best of my knowledge, without circuit modification, EL34s shouldn't be used in in the 502. On the other hand, the 302B is designed to run EL34s. Maybe things have changed recently but that's been my understanding. Why not contact JoLida directly (I'm sure they're well aware of what Shenda is doing) or Underwood HiFi (very knowledgeable) if your seller can't help?