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6p3p tube amplifier kit

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#207
My measurements today:
mains voltage 123 volts.
Output of rectifier 358 volts
After choke 345 volts
Plate to cathode voltage 300 volts
Cathode resistor voltage 20/23 volts (tubes aren't matched)

Using this calculator my bias is roughly 66mA which is ideal for either EL34 or 6P3P.
Weber Bias Calculator

Don't forget that there is current flowing through the screen.
 
#212
I would not do that. Inductor input filters are only good with circuits that draw a small fixed amount of current (not power amplifiers). It will exhibit poor filtering performance as soon as you draw more current.

By the way, my secondary winding is also marked 300 volts. Adding another RC element to the power supply seems like the best bet followed by changing to a rectifier that drops a few more volts.

What rectifier did yours come with? Is it a 5Z4P?
 
#214
I got also a 5Z4P. I have an old Siemens GZ34 on the bench, but voltage drop is lower than the 5Z4P,so it is not a solution. I will probably try the RC filter approach.

In the meanwhile something got wrong, the sound became too low and distorted. Not sure why, but I had a nasty noise under the wood after installing the ground resistors in the 6P3P tubes heaters. Nothing seems burned, took out the resistors and everything was fine. Now it started to distort. Any clues of what happened?
 
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