Boyuurange Reisong A12: Doing the Mods Video #1

First of a 2 part step by step video on how to do these mods to your A12. The only major part replaced was the rectifier tube, everything else was just some resistors and 1 capacitor was added. This transformed the test results, huge distortion reduction and at the same time extended the frequency response.

I initially thought I would be keeping the output tube cathode bypass capacitor, but I then realized changing the cathode resistor would require the bypass cap also be changed, and I have spec'd a 470uf 35V replacement.

This A12 amp is sold on Amazon for just under $500 and for many folks this is their first taste of a tube amplifier. I plan to do a complete video series, critically testing this and exploring ways to improve the sound just like I did on the A50 amp. I know a lot of people own these and like them, I'm curious how they actually perform!

I will upload a schematic and updates after I finish working on this amp.
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