Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Johnnydoright on January 28, 2022, 12:38:25 am
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I have a question regarding filter capacitor value and 60 cycle hum. I recently completed a rebuild of an earlier 5E3 clone using a Hoffman layout and parts from the Hoffman site. It all went well, and the amp sounds fabulous. I also have similar amp, also a 5E3, but it came as a kit from Stumac. I have noticed the STUMAC amp has less noise than my Hoffman build. The only difference in the parts are the larger filter caps are greater value in the STUMAC amp (22mf as opposed to 16 mf in the Hoffman). The hum is not significant, and not even noticeable while playing through the amp. I did the grounds as shown in the layout for both amps. I am just wondering if the higher cap value provides a quieter floor? Being relatively new to the amp building thing, I was hoping I could get some input from some of you more seasoned builders. Oh, and this was a redo of my Chinese 5E3 that proved to be a significant challange, but I did get going with a little guidance from the pages of this fine forum. Thanks for the help, and keep soldering!😁
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Check out this link https://www.ampbooks.com/mobile/amplifier-calculators/RC-ripple-filter/calculator/
My personal experience is that going from 16 to 22uF as the first cap (and remember that the "first cap" is simply a reservoir, not a filter) will not impact the noise floor to my ears (which are admittedly old).
The answer is likely to come from layout/construction details, and component selection. As such, can often be tough to nail down.
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Thanks, I will check it out😃
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You say 60Hz but you also say "new".
The B+ caps should not have 60Hz on them, but 120Hz.
120Hz is incomplete filtering of the rectified AC.
60Hz is leaking right from wall-wires to amplifier stages.