Emg77
Well-known member
Picked up a 1980 JMP 2204 and the same Era JCM800 cab with stock G12-65's. It sound pretty good. It came loaded with El34's. The guy told me it had the conversion done years ago. At any rate I break it ou of the head shell to check it out and bias it.The bias adjustment was maxed out and I was getting 7ma's on one tube and 11 on the other. I was thinking maybe they were cold set of tubes. So I dropped some other el35's in. I wasn't hardly getting a reading on them. Then it occurred to me, I bet it didn't ever have the conversion done! So I dropped a pair 6550's in and i was getting 37ma. This still being maxed out. Still cold.
I'm not sure I want to commit to a conversion yet. I'd like to hear the El34's in the appropriate bias range. Anybody have any suggestions? Maybe alligator clip some different value resistors on top of the bias resistor? Any input would be great. Thanks!
I'm not sure I want to commit to a conversion yet. I'd like to hear the El34's in the appropriate bias range. Anybody have any suggestions? Maybe alligator clip some different value resistors on top of the bias resistor? Any input would be great. Thanks!