Re: 120W PP EL34 amplifier re-born.
"ali will not shield from magnetically induced hum." Thought it did? Was under the impression steel didn't as it can become magnetised. Seems I'm wrong - "the 'shield' needs to be of a material that has high permeability or low reluctance (they are reciprocal like resistance and conductance). The permeability of iron is .25 and the permeabilitu of aluminum is 1.25 x 10>-6. Nearly a million times less able to reduce magnetically induced hum."
This galling as I am pretty sure I read that ali was a good shield in a chapter on chassis building in toob amps. Oh well, you live and learn.
Andy.
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Curiosity hasn't killed this cat...so far.
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