• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6550/KT88 PP amp

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
530 volts in triode mode will make most new production KT88 / 6550 tubes very unhappy, though you might get away with this much B+ with cathode bias.

Many builders say that you can bend the screen grid rating in triode mode, but the tubes don't know what mode they are in, and sitting idle with 500+ volts on the screen may invite a runaway on some tubes.

Real GE6550's may be the exception, but I trust mine to 450 volts in triode, and with a 3300 ohm load, I get 75 watts.

YouTube
 
I can use a bucking transformer to lower the B+ as the HV is from a separate transformer.

I've had the BO-14 outputs for some time and have no idea where more would be available. I'm set on using 5687's as a driver, but I am thinking of using 6dj8 as a voltage amp biased with LED's. I could use a schematic showing how to implement this. Any thoughts??
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.