Phono III with TAD valves.

[bob orbell]

Hi all, I have put together another Phono III board with new selected components and 3 new TAD ( tube amp doctor ) ECC83 tubes, this is the first time I have used these tubes, my concern is at switch on the heater filaments flash white, almost like a flash of lightning and I don't like it, surely this is doing the elements no good ? voltage from PSU is good at 6.2 volts, any thoughts. Bob

[John Caswell]

Hi Bob et al,
This quite normal and has been going on for years. There were always "complaints" about Mullard valves doing this but it is not a problem.
I suspect the TAD valves are possibly Ei who I believe bought the Philips/Mullard factory gear.
Do not worry about it, I have ECC81/2/3 that do this that are 10s of years old.
It is much more important to make sure the heater voltages are correct (6.3/12.6v) or slightly under (6.2/12.4v) but don't get paranoid about it!

John

[bob orbell]

Thank you John, the two E88CC Mullards I had from you some time back glow a little when powered up, but I am alarmed at how bright the TAD 's are, thanks again. Bob