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.
Just replaced the Electro Harmonix 300B's with some Sophia Electric Globe Mesh Plates and am wondering why on some start up, one or other of the valves glows like a 'Christmas Tree'. I usually switch off then back on and all is OK.
My engineer is going to fit some new permalloy output transformers which is an upgrade to eliminate the hum. Do you think the 'Christmas Tree' problem is something that he can deal with? The 300B is a Dignity Audio Mono Block supplied by Monarchy Audio in San Francisco.