Hi all,
I did a childish mistake when I tried last time to find the best grounding variant but doing this mistake I finally got the answer if 160 uF for the first chain of filtering is enough not to have any hum noise into the speakers with the ear at 2 cm away from it : is enough.
Like I said , I build another stage of filtering consist of 100R/5W resistor followed by 2 x 330uF capacitors in series.This stage is build on another PCB placed under the right side OT where I have a free space --> a wire link the PS ground of that 2 PCB*s.
Then one wire goes from first stage to the second stage of filtering and another wire is coming back from there to the main PS PCB for B2+ , B3+ and -Vg.
The mistake I did is to forget to conect the ground wire from these 2 PCB*s !!!!!
So I didn*t have 2 stage of filtering , only one stage and 100R resistor in chain!!!And no hum noise.
With one stage of filtering I have B+ = 463V , B2+ = 421V , B3+ = 192V
With 2 stage of filtering I have B+ = 456V , B2+ - 416V , B3+ = 188V.
My question is if is OK to operate with B+ at 463V ?It is not to much?(EL 34 are biased at 40mA per tube)
Is worthing to keep the second stage of filtering?
Another question is what is the real capacitance when 2 x 220uF are in series with the power transformer having 350V center taped like in original schematic?It is 110uF or 220uF the rectifier see? (because every 220uF cap filter 175V from center tap to the end of winding).
Regards,
I did a childish mistake when I tried last time to find the best grounding variant but doing this mistake I finally got the answer if 160 uF for the first chain of filtering is enough not to have any hum noise into the speakers with the ear at 2 cm away from it : is enough.
Like I said , I build another stage of filtering consist of 100R/5W resistor followed by 2 x 330uF capacitors in series.This stage is build on another PCB placed under the right side OT where I have a free space --> a wire link the PS ground of that 2 PCB*s.
Then one wire goes from first stage to the second stage of filtering and another wire is coming back from there to the main PS PCB for B2+ , B3+ and -Vg.
The mistake I did is to forget to conect the ground wire from these 2 PCB*s !!!!!
So I didn*t have 2 stage of filtering , only one stage and 100R resistor in chain!!!And no hum noise.
With one stage of filtering I have B+ = 463V , B2+ = 421V , B3+ = 192V
With 2 stage of filtering I have B+ = 456V , B2+ - 416V , B3+ = 188V.
My question is if is OK to operate with B+ at 463V ?It is not to much?(EL 34 are biased at 40mA per tube)
Is worthing to keep the second stage of filtering?
Another question is what is the real capacitance when 2 x 220uF are in series with the power transformer having 350V center taped like in original schematic?It is 110uF or 220uF the rectifier see? (because every 220uF cap filter 175V from center tap to the end of winding).
Regards,