In Reply to: This is an unbelievable little Chinese phono stage posted by Michael Samra on March 25, 2014 at 21:03:10:
I dealt with some buzz in the RCA classic hybrid circuit that Eli and I tend to promote. Try some quieter tubes and the spiral LPS as Eli suggests. If it still buzzes, see if the filament supply is floating. If so, try grounding to the B+ supply. That may help.
Other fixes (that may be too much work) could include elevating the AC heaters or converting them to DC regulated. In the case of the RCA hybrid MOSFET follower, we also needed to tweak R6 in the RCA schematic because the second cathode was now directly grounded, and then increase the coupling cap to compensate so that the RC constant was maintained. This also served to reduce gain slightly, which helped residual hum as well.
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Follow Ups
- RE: This is an unbelievable little Chinese phono stage - jyourison 07:04:22 03/26/14 (0)