Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bieworm on January 17, 2022, 02:32:11 pm
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Hey guys..
Is this going to be a problem? Full wave bridge rectifier next to the cathode bypass cap and resistor?
Fwiw it's an 18W build, cathode biased. Is this stupid?
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If that's the PA tube R & C then there's no problem, now if you cross the signal wire for the tube over the Rectifier wires, you might get coupling
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Not a problem.
100Ω will likely bias your EL84s very hot. 130Ω is more commonly used and I like to use 150Ω/5W just to run the tubes a bit cooler. My dual lite cathode resistor only dissipates .67W. Your 25W resistor is much overkill and will likely run only slightly warm. But if it had to dissipate it's full rated power it would burn the board.
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..Full wave bridge rectifier next to the cathode bypass cap and resistor?...
I don't see a full wave bridge rectifier? Or do you mean the diamond turrets?
All the amplifier returns go toward the "-" end of the main filter cap. Yes that connects to the FWB via a wire, but there are BIG current surges in that wire. The cap end is the quiet end.
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The diamond is going to be the FWB rectifier indeed. The 100R is a sag resistor that's connected to the stand-by switch. The ground of the rectifier will be at the edge towards the star ground. I will put in a 180R cathode resistor. That's what I always tend to end up with in my 18 watt builds.
I just found a layout from RobRob's 5E3 deluxe micro, where he put the rectifier also next to the cathode bypass cap/resistor.
Thanks for the answers. I feel much better now!!