Greetings all,
What is the 390 pf cap from the screen of the KT88 to the pentode of the
6AN8 for? If it's feedback, I thought the 1K/750 pf from the 16 ohm spkr tap did that.
Thanks,
Ray
What is the 390 pf cap from the screen of the KT88 to the pentode of the
6AN8 for? If it's feedback, I thought the 1K/750 pf from the 16 ohm spkr tap did that.
Thanks,
Ray
It's there to HF balance the two sides of the push-pull to make up for imbalances in though output transformer. The DCR, leakage inductance, and capacitance are different from one half to the other because of the winding geometry.
AFAIK it's there to tweak the square wave response of the amplifier by correcting for anomalies produced by the output transformer. And it is feedback.
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