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Audio and Video Talk
Valves / Vacuum Tubes
How to design a Power Transformer for a Push-pull tube amplifier?
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<blockquote data-quote="Ampdog" data-source="post: 195894" data-attributes="member: 144"><p>Something is very funny here - problems with CFs are mentioned, but the given circuit works in class-A, where the average signal current drawn is constant, unless something is heavily overloading. I do not see that possibility in the given circuit when used as a pre-amplifier.</p><p></p><p>But I have misgivings about an LC <em>following</em> a voltage regulator. I have never found the absolute voltage to affect matters in a pre-amplifier, at least not varying within the normal mains fluctuations. But calculating at rectified mains frequency (100 Hz), the 10?f capacitor has a reactance of 160 ohms - not all that low!. The series choke has all of >9K impedance at 100Hz, which just about renders the regulators' work useless at signal l.f. I am thinking that the right place for the regulators might be after the choke, not before it, if you want to use regulators at all. Then also in this day and age the 10?F might be replaced by something quite higher, still with a reasonable physical size. OK, one might want to maintain the original values, but ... </p><p></p><p>But as said, something is amiss if one considers that early power amplifiers like Williamson and Leak operated with 8?F power filter capacitors, at at least some 10x the signal current to deal with, without problems. So perhaps some thought in that direction. </p></blockquote><p></p>
[QUOTE="Ampdog, post: 195894, member: 144"] Something is very funny here - problems with CFs are mentioned, but the given circuit works in class-A, where the average signal current drawn is constant, unless something is heavily overloading. I do not see that possibility in the given circuit when used as a pre-amplifier. But I have misgivings about an LC [I]following[/I] a voltage regulator. I have never found the absolute voltage to affect matters in a pre-amplifier, at least not varying within the normal mains fluctuations. But calculating at rectified mains frequency (100 Hz), the 10?f capacitor has a reactance of 160 ohms - not all that low!. The series choke has all of >9K impedance at 100Hz, which just about renders the regulators' work useless at signal l.f. I am thinking that the right place for the regulators might be after the choke, not before it, if you want to use regulators at all. Then also in this day and age the 10?F might be replaced by something quite higher, still with a reasonable physical size. OK, one might want to maintain the original values, but ... But as said, something is amiss if one considers that early power amplifiers like Williamson and Leak operated with 8?F power filter capacitors, at at least some 10x the signal current to deal with, without problems. So perhaps some thought in that direction. [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
How to design a Power Transformer for a Push-pull tube amplifier?
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