Roberto’s PP-18

Not all amps work first time – Roberto’s cage-covered PP-18 needed some troubleshooting, due to hum. “I rewired the valve heater ‘chain’, the grounding and some of the output transformer wires and the hum just disappeared. I wanted to use it as a platform to tweak to my liking, but this thing sounds so good as is that I think I’m going to leave it this way.”