Now I like my amplifiers like I like my women, hot dirty, smelly, well worn, old and seen lots of action. This Fender Bassman was just the ticket. She’s a lovely amplifier and we had been acquainted a few years ago when she came in for a good service. Lots of resistors were replaced, the bias circuit was not right and had lead to the demise of the 6L6G’s output stage. All coupling capacitors were tested and replace with new, making sure the outer foil was pointing to the right side. This version is the two input model, AB165 I think. With the amp up on the bench and a quick look under her nightie, showed nothing obvious. I could not get any more than about 20 watts from her. The output valves that had been replaced last time didn’t look stressed and the AVO tester showed they were as healthy as the day they were born. Bias all okay, the ‘scope showed the output clipped top and bottom at the same time. One thing that was odd was that when the test sine wave input was quickly changed in amplitude, the output wandered all around with a big offset. All looked good at the front end of the amp, so I peaked at the 12AT7 phase splitter valve. If one half of this double triode dies, all kinds of odd things can go on. So, a replacement to family and hey presto, happiness was restored. A good full 50 Watts of angry pixies splashed onto the floor. Boy do these amps sound nice.
