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Audio and Video Talk
The Vintage Audio Section
Any amp geniuses here willing to give advice?
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<blockquote data-quote="ludo" data-source="post: 847939" data-attributes="member: 691"><p>If using a pair of 1N4148s in place of D408 you could place a resistor in parallel to one of the pair. 100 Ohm or so could be a good start. You can still trim bias on R462 then.</p><p></p><p>1N4007 used at low current (~9mA here) might already give lower Vf than 1N4148 and be easier to insulate and mount?</p><p></p><p>You might consider removing that whole bias string and R464, making an adjustable single transistor bias generator on a small PCB (strip-board even) to replace it, and mounting that where D408 was on the heat sink. (Ideally it might go right on the mounting tab of one of the output devices.) Won't look original though.</p></blockquote><p></p>
[QUOTE="ludo, post: 847939, member: 691"] If using a pair of 1N4148s in place of D408 you could place a resistor in parallel to one of the pair. 100 Ohm or so could be a good start. You can still trim bias on R462 then. 1N4007 used at low current (~9mA here) might already give lower Vf than 1N4148 and be easier to insulate and mount? You might consider removing that whole bias string and R464, making an adjustable single transistor bias generator on a small PCB (strip-board even) to replace it, and mounting that where D408 was on the heat sink. (Ideally it might go right on the mounting tab of one of the output devices.) Won't look original though. [/QUOTE]
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Audio and Video Talk
The Vintage Audio Section
Any amp geniuses here willing to give advice?
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