Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: labb on August 26, 2021, 11:07:22 am
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Where should the first Capacitor in the the power supply of an amp go...Before the standby switch or after. I have built amps both ways and have not had a problem and when I start looking at schematics I see it both ways. Mostly before the standby switch. I tend to put it after the switch. Which should it be..
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Neither side of the standby switch, because there isn’t one :icon_biggrin:
Why is one needed?
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Sluckey answers that question here: Standby switch Q (el34world.com) (https://el34world.com/Forum/index.php?topic=27897.0)
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I'm with pdf64 on this :icon_biggrin: , But I think the design is a little more complicated..If you put the cap before the switch what do you do if you use bleeder resistor to discharge the caps when you power down the amp...maybe use two, one before the switch and one after...or instruction to always give the amp time to discharge before turning off the stand by.
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You put the 1st cap before the standby. But you take the dcv from the 1st filter cap to feed the power tube plates/OT CT -after- the switch. This way you take some of the in rush current strain off the rectifier tube.
You can put the bleeder R across any of the filter caps.
When you turn off the amp, you leave the standby on/in play mode. Because the tubes are hot, they will continue to draw current draining the filter caps. Hit a chord, then turn off the amps power switch leaving the standby in play mode and you can hear the volume drop off to nothing when you do this.