Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: chaf87 on December 22, 2025, 08:43:49 am
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Hello everyone. I'm starting to assemble my second Hoffman 5F6-A. The first one was long time ago. I have a question about the grounding system: in the specific document on grounding, Hoffman instructs us to ground the preamp filter caps to the ground bus and the B+ filter caps to the chassis ground point. However, in the 5F6-A schematic, all the filter caps are grounded to the chassis ground point. Did I miss something? Just to clarify: when I made the Bassman a few years ago, I strictly replicated what was detailed in its schematic. Thank you very much. :m7
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One or both of the arrangements you show may work fine, perhaps depending on other aspects of the circuit's implementation.
To help understand what's happening, see https://www.valvewizard.co.uk/Grounding.pdf
Given where you are, you'll probably need to read it many times.
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One or both of the arrangements you show may work fine, perhaps depending on other aspects of the circuit's implementation.
To help understand what's happening, see https://www.valvewizard.co.uk/Grounding.pdf
Given where you are, you'll probably need to read it many times.
Ok. Thanks a lot. I'll read this article right now.
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If you get stuck with it, don't be afraid to ask :icon_biggrin:
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If you get stuck with it, don't be afraid to ask :icon_biggrin:
Ok! I think I'll just follow the amp's layout.
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... in the 5F6-A schematic, all the filter caps are grounded to the chassis ground point. ...
What schematic are you thinking of, eg https://el34world.com/charts/Schematics/files/Fender/Fender_bassman_5f6a.pdf
A real 5F6a looks to have the decoupling cap for the preamp supply mounted on the circuit board.
Whatever, if you're unsure of the theory, it's a very good idea to follow a proven arrangement.