The transformers of one of my china-sourced amplifiers (6P3P push-pull) sing so much that they are audible at low volume even when connected to a speaker. They are neatly encased in a nice metal enclosoure, but aren't really potted. Inside the enclosoure there is just the smallest amount of tar-like compound to tack the transformer in place. Each transformer enclosoure has a footprint of only 70 x 45 mm, finding a replacement will be difficult.
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As has been said, your are using a load resistor in place of a loudspeaker?
Usually an output transformer only "sings" when driven at high power. In normal operation with speakers it's not audible. It's magnetostriction.
I have heard output transformers sing like this at very low power when the output stage or even the whole amplifier is oscillating at some high frequency way out of the audio band.
Compare idle current of the amplifier with a shorted input verses a small input. Should be similar.
832 does like to oscillate on its own without some simple precautions.
Cheers
Matt.
Usually an output transformer only "sings" when driven at high power. In normal operation with speakers it's not audible. It's magnetostriction.
I have heard output transformers sing like this at very low power when the output stage or even the whole amplifier is oscillating at some high frequency way out of the audio band.
Compare idle current of the amplifier with a shorted input verses a small input. Should be similar.
832 does like to oscillate on its own without some simple precautions.
Cheers
Matt.
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