WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
I have delivered about 50 JJ 6L7GC during 2015 and noone have complained. Most have been to guitar amps ( they tend to be pushed around, shaken and abused mechanically, on the other hand the total number of power on hours is limited)