In Reply to: Amp hum - do I have an issue (or just need education!)? posted by 91derlust on November 2, 2015 at 00:47:12:
Thank you all for taking the time respond.Before building this amp, I spent a good deal of time researching grounding approaches and selected a multiple-star scheme, but it seems it can still be tweaked a little.
I learned a lot from the build, but it did include some compromises that future builds will avoid.
Strategy (for starters):
1/ Add 10 to 100R between 0v signal grnd and chassis.
2/ The wire to the control grid cap of the 6C6 is unshielded and runs near the output transformer; it was an unplanned change. The wire could be picking up noise. I will use some shielded wire to the control grid.
3/ Recheck the wiring to ensure connections are correct and nothing is touching the chassis.
4/ Consider returning the 6C6 cathode circuit to the PS cap that supplies the stage (rather than to the screen bypass cap).The 0v signal grnd connects to the chassis in place only: close to the safety earth connection. In future builds, it might be better to make this connection at the RCA return.
Thanks again all.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 11/07/15
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Follow Ups
- Thanks and strategy. - 91derlust 12:17:06 11/06/15 (0)