Hello everyone,
Will having grid bias on a tube during warm-up have any detrimental effects? The high voltage for plate and screen have a 3 minute delay.
Thanks
Ray
Will having grid bias on a tube during warm-up have any detrimental effects? The high voltage for plate and screen have a 3 minute delay.
Thanks
Ray
Ya, three minutes is a long time for preheating receiving tubes.
I stopped using a delay when I realized it really isn't needed with normal tubes and voltages 600V or less.
I stopped using a delay when I realized it really isn't needed with normal tubes and voltages 600V or less.
For 59 years now, the console stereo in my dining room never needed any help, or delays.
It's majority of tubes are original in the tuner/pre - datecoded "62", and still fine after testing.
And the original amp's tubes (including 5AS4A rect) all tested well too.
59 years without any damn delay stuff!
If the grid bias voltage available -almost- immediately (faster than anode voltage, which is grooving -relatively- slowly, as HV capacitors charging) usually no need HV delay...if the cathode is enough warm.
See the tube curves: at proper negative bias with increasing anode voltage the anode current stays within the safe area.
The cathode heating vs. anode voltage is another problem.
See the tube curves: at proper negative bias with increasing anode voltage the anode current stays within the safe area.
The cathode heating vs. anode voltage is another problem.
I suppose the difference now is those consumer items that have lasted so well are no longer consumer items, at least as NOS. I replaced the tubes on a pair of Quad IIs with some NOS ones, and a sobering thought was the combined age of the 10 tubes was well over 500 years!