I have been building some 5E3s lately using salvaged non guitar amps. The voltage from the PT is a little high. My question is: without lowering the overall voltage, what is better, to raise the cathode resistor for less current, or to lower it for less voltage?
I was interested to see the interaction between these to elements and to compare the sound of each. So, I used a a rotary switch with several values that could be switched in parallel with a main larger resistor so i could see what each value did without having no resistor for the fraction of a second while switching. Because of the parallel thing, the values aren't ideal but you get the gist. Watts are calculated via the weber bias calculator.
Here's what I got:
Res.
Ohms__mA___Volts__Watts
266----40.2----383----15
354----33.8----390----13
498----27------400----11
572----24.6----403----10
Before the test, I have been biasing around 13.5 watts dissipation. To get down to 12w puts almost 400 volts on the plates. 13.5 brings the mA about to about 35. which is worse? And what suffers? What makes for shortened tube life? What makes for shortened transformer life? Any expert opinions available? More volts less mils, or the reverse?
I was interested to see the interaction between these to elements and to compare the sound of each. So, I used a a rotary switch with several values that could be switched in parallel with a main larger resistor so i could see what each value did without having no resistor for the fraction of a second while switching. Because of the parallel thing, the values aren't ideal but you get the gist. Watts are calculated via the weber bias calculator.
Here's what I got:
Res.
Ohms__mA___Volts__Watts
266----40.2----383----15
354----33.8----390----13
498----27------400----11
572----24.6----403----10
Before the test, I have been biasing around 13.5 watts dissipation. To get down to 12w puts almost 400 volts on the plates. 13.5 brings the mA about to about 35. which is worse? And what suffers? What makes for shortened tube life? What makes for shortened transformer life? Any expert opinions available? More volts less mils, or the reverse?
Comment