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Just MeJust Me

The 110V Chinese transformer problem (again)

Sooooooooo ... the Chinese amplifier kit I am building seems to suffer from this 110 volt vs. 120 volt AC issue as well. Although the kit now comes with a transformer clearly labeled 115VAC, I think they just changed the label on the transformer and not the transformer itself.


Here are my actual measurements. How big a problem is this?


Transformer specifications (no load) vs. actual (no load)

115VAC in -> actual 121VAC

275VAC out -> actual 300VAC

6.3VAC out -> actual 6.9VAC

3.25VAC out -> actual 3.5VAC


Power supply specifications (no load) vs. actual (no load)

380V out -> actual 414V

295V - 300V (regulated) not to exceed 300V -> actual 311V ... (the directions are very specific not to exceed 300V here due to the Chinese 6N1 tubes not being able to handle more)


Someone on diyAudio suggested that I order a couple of small power resistors to reduce the power to the filaments, which I ordered 2 weeks ago before I even started building, so I do have those on hand. They are 0.05 ohms 3W and 0.022 ohms 3W.


The kit also includes an "optional" 91V zener diode, I assume to replace one of the 100V zener diodes?


So I am left scratching my head? Do I really have a problem and can it be addressed without a 110V power supply or bucking transformer? I have the little resistors I mentioned for the filaments, and there is the 91V zener diode in the kit.


Tubes are 2*6N1 and 4*6P14 output tubes, not ECC85 and EL84 as shown on the schematic.







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Just Me
Feb 25, 2023

In this power supply, Is it as simple as increasing R1?


Calculator: https://www.ampbooks.com/mobile/amplifier-calculators/RC-ripple-filter/calculator/

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