• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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Fairchild 255 Rebuild

I bought a pair of Fairchild 255a's which were damaged in a flood. No hard feelings to gut the insides as they were completely wrecked -- except for the transformers. Here's a picture of one not repaired, and one in which I have improved the bias circuit and put in screen regulation:
 

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Mullard 5-20's

Also a rebuild and redesign of circuit. They were not as bad in appearance as jackinnj Fairchild's, but the sound - all I could hear on them on arrival - believe it or not - was a local radio station. Weird thing, I tested the supplies, connected only a speaker, no input signal, and the radio station came up :scratch:

Any way, I found an improved circuit - by Mr. Claus Byrith - rebuild the whole and now I can hear good solid music ;)

Fronts:
 

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WD40
very glad to see your masterpieces shown on this site. You are too miserly to display your amp. colletion on NiuShiFu, though nearly every old man there knows that you are hiding a goldmine. When will your 813 venture be finished? I am looking forward to a surprise. Here is my mahine which is not much satisfactory and I use it as a testing one. With OPT input resistance as 2.5K, it can be powered by a couple of Shuguang 6P3PJ, the cheap equivelant of 6L6, or four 6P6P, the equivalent of 6V6GT, two each channel. The driver is 6N2, a tubel close to 12AX7. Well, the sound effect is, how to say, just so so, perhaps for the quality of OPT, with high distortion in the high frequency band. This is what I ever mentioned to you.
 

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