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Audio and Video Talk
The Vintage Audio Section
Mullard 5-10 amplifier kit sold by Sterns
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<blockquote data-quote="Ampdog" data-source="post: 761281" data-attributes="member: 144"><p>Under which thread to post now ....</p><p></p><p>F_D,</p><p></p><p>I have two well-built units with the same transformers as your example in the other thread, but as soon as the Partridge power transformer comes near the steel chassis the output hums unacceptably. Not so with other power transformers.</p><p></p><p>They are thus standing in a corner, donated by the previous owner a few years ago, for the same reason. I am not sure what to make of it. I presume yours did not have a hum issue or you would have mentioned it. I am too tied up at present to spend time investigating the power transformer for stray flux, also not looking forward to rebuilding the lot on an aluminium chassis. (As mentioned before, in the past I often had trouble building on a steel chassis as a result of stray magnetic induction. Blast!! Still commercial brands seem to get away with it .... )</p><p></p><p>If you care (or anybody else using Partridge power transformers) I would like to hear whether similar experiences were had elsewhere.</p><p></p><p>Kubusi, glad to hear that you have UL output transformers. Pentode output stages can be rather critical regarding the often severely variable impedance of a loudspeaker load. (I imported a few Gilson OPTs in the day; very good transformers those and not that expensive at the time.).</p></blockquote><p></p>
[QUOTE="Ampdog, post: 761281, member: 144"] Under which thread to post now .... F_D, I have two well-built units with the same transformers as your example in the other thread, but as soon as the Partridge power transformer comes near the steel chassis the output hums unacceptably. Not so with other power transformers. They are thus standing in a corner, donated by the previous owner a few years ago, for the same reason. I am not sure what to make of it. I presume yours did not have a hum issue or you would have mentioned it. I am too tied up at present to spend time investigating the power transformer for stray flux, also not looking forward to rebuilding the lot on an aluminium chassis. (As mentioned before, in the past I often had trouble building on a steel chassis as a result of stray magnetic induction. Blast!! Still commercial brands seem to get away with it .... ) If you care (or anybody else using Partridge power transformers) I would like to hear whether similar experiences were had elsewhere. Kubusi, glad to hear that you have UL output transformers. Pentode output stages can be rather critical regarding the often severely variable impedance of a loudspeaker load. (I imported a few Gilson OPTs in the day; very good transformers those and not that expensive at the time.). [/QUOTE]
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Audio and Video Talk
The Vintage Audio Section
Mullard 5-10 amplifier kit sold by Sterns
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