Postby Dave W » 12 Jan 2011, 17:18
I am not a tech.
Some amp can go from EL34's to 6L6's with just a bias check.
EL34's, KT77, 6L6, KT66 are capable of about 25 watts max each.
6550,KT88 about 35 watts each.
I read about the difference from the Eurotubes website and other tube sites.
I would not go up toi a 6550 or KT88 without asking a tube store like Eurotubes etc. If they have done this. There are factors like watts, inpedence etc. with the tubes. Going up like that may put an improper load on your traansformers etc.
On the Eurotubes site I see KT88's in Mesa Kits and mixes of tubes, but I think that those sets are measured and picked to match. Like a KT88 measured out/graded at a particular level that will work in a regular 6L6 spot.
Real simple, just call Eurotubes or who ever you like and say what amp you have and what you would kike to do and if they have a grade of a particular tube that you want to try that will work in that application and if they ever did that before.
They have schematics on many amps and have measured and tested many amps that have come thru their store to be retubed etc. They have data and will let you know if it theoretically or in real life has worked before.
-- Wed Jan 12, 2011 8:26 pm --
Reread your post....a few more responses.
KT88 compared to EL34.......generally more low end and balls.........can also improve the clean tone from what I heard, but low end thunder when pushed.
Most I have read said if it runs 6550, then replace with KT88 for improvement.
Is it still the JCM 900 you have.......if so then please consider if you must try different tubes trying KT77's......not 66 not 88, but 77's.
I personally do not care for EL34's. Always replaced with KT77's and prefered the difference. No mods, more low end, better cleans when you want them. To each his own though.