I traded my first car, a 1949 Plymouth for one of these amps back in the early 90's. I built tube stereo amps from the 60's through the 80's but had Carver / Phase Linear stuff at the time. The old Scott was piled in a corner of a barn full of old cars with a matching tuner piled on top of it. This had broken one of the 5U4's, one of the original Scott branded Mullard EL34's and both white ceramic resistors near the output tubes. I replaced only these components, plugged it in, and within a week the solid state stuff hit the closet.
The Scott took it's place in the stereo rack and stayed there. It rekindled my desire to build tube stuff, and would eventually be replaced with a DIY push pull 300B amp, and later more DIY stuff. I sold the Scott amp and tuner at the Dayton hamfest a few years ago.
Don't mess with the design or destroy it's originality. They are nice sounding amps and worth quite a bit of money in unmolested condition.
Rebuilt the tube filament/bias supply. I went from 7 volts per 12.6 volt X 6 tubes in series to 11.5 volts per 12.6 volt rated tube. Bias has less than .001 AC ripple. Likely .0001 AC ripple, but the power supply software does not calculate below .001 AC ripple.
This change got rid of two can capacitors that freed up more space for the new HV power supply capacitors. Originally 40uF to now 750uF to the power tubes. I did replace the two 5U4 tubes with SS rectifiers and used a dropping resistor to get voltage back to spec. High B+ is now a CRC circuit.
This change got rid of two can capacitors that freed up more space for the new HV power supply capacitors. Originally 40uF to now 750uF to the power tubes. I did replace the two 5U4 tubes with SS rectifiers and used a dropping resistor to get voltage back to spec. High B+ is now a CRC circuit.
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