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'm using adaptation of old Mullard ECL82. It's serves me for many years now. Since I'm listening it in my workshop it is used a lot and I need to replace tubes every 1-2 years. It's ''ON'' at least 8 hours every day. Cool amp indeed.