• 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.

PP KT88, Need help!

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I haven't been able to check anything when the feedback is connected for that channel. It is so loud I have to turn it off and I don't have a resistor box handy to load the output.

I wouldn't worry about a resistor box as such - many resistor boxes are not designed to handle significant power. I would find a pair of 8 ohm or similar wire-wound resistors rated to 25 or 50 watts. They can be ceramic, but I like using the aluminium clad ones since they can easily be bolted onto a more substantial piece of metal. Here's some.
 
Scott17 I will forever love you.

THE AMP IS FIXED! Not only that, it COMPLETELY exceeded my expectations. I cannot believe I've spent weeks and weeks trying to fix something that was just the primary of the left OPT wired in reverse. It was positive feedback all along!

I also added 1.7k grid stoppers to all my KT88s and replaced the capacitors for the fluttering channel.

THANK YOU EVERYONE! I was so disappointed when this thing didn't work but thanks to everyone throwing their ideas, it is finally fixed... And it sounds AMAZING.

Thank you again!
 
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