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11-16-2018, 06:30 PM
Hello,
I have this Classic 30 that's been sitting in a corner for quite some time and I thought I'd upgrade it a bit. I had been altering some capacitor values before, but thought the circuit could be improved in some way safety-wise. I'll be adding individual bias pots for each tube as well as measuring jacks, but what struck me right from the start was the lack of proper screen protection. TUT suggests providing individual 2,2K/2W screen resistors for each tube in those low-wattage EL84-driven amps which is exactly I'm going to do, but one EL84 in each pair has a 100R resistor on the screen supply. I gather that's a protection against oscillation between doubled up tubes, but will they still be neccessary once the 2,2K resistors are in place?
Tomislaw
I have this Classic 30 that's been sitting in a corner for quite some time and I thought I'd upgrade it a bit. I had been altering some capacitor values before, but thought the circuit could be improved in some way safety-wise. I'll be adding individual bias pots for each tube as well as measuring jacks, but what struck me right from the start was the lack of proper screen protection. TUT suggests providing individual 2,2K/2W screen resistors for each tube in those low-wattage EL84-driven amps which is exactly I'm going to do, but one EL84 in each pair has a 100R resistor on the screen supply. I gather that's a protection against oscillation between doubled up tubes, but will they still be neccessary once the 2,2K resistors are in place?
Tomislaw
