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.
So I have an amp using the Soviet made GU 19-1 (or simply GU 19) tubes, I wonder are the German made SRS4451 and QQE06/40 having the same specs and can be interchangeable?