Hey guys, doing my best to learn a couple of things so don't shoot me or assume in an expert (because I'm not). I have recently bought a Carlsbro TR60 combo (actually two but one is used for parts), and found out the power section is somewhat different than what I've already seen in JMP Marshalls. Most importantly there is not a bias pot. I use a TAD tool to check cathode current (which I know is different from plate current), dropped in a fresh pair of TAD tubes, and a bit concerned with the 46-48 mA it's pulling in idle at 470V. According to the calculations and assuming 8W from the screens (correct me when this is wrong), it calculates to just about 70% of max. plate current, which is supposed to be the real limit. I read a very nice and long post on 70% vs. 90% so I understand what this means more or less. So digging a bit deeper to see how this TR60 could be described, I found the term non-adjustable fixed bias (where people also say that doesn't exist as it is still adjustable by changing the resistors). So when looking at the schematics, please correct me when I'm wrong but the addition of a 10k bias resistor in series with the 47k resistor should resolve that. Be gentle on me, I'm new to this stuff and eager to learn ;-) That seems to be case with the TC100 amp So is it really as easy as that, adding the adjustable 10k resistor, and then lowering cathode current by increasing the value of the 47k resistor to e.g. 50 or 52k ohms? Or should I take higher resistance, like 27k which is used in the super lead? Or am I still missing something fundamental here? At this point of my learning curve I have no interest yet in measuring on the plates themselves.