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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

DC restorer

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Can someone explain the DC restorer zener circuit and how to apply it? I have the same 'Base' model vintage amplifier used in Bob Carver's NEW design 'http://www.bobcarver.com/vta20s.asp' in the vintage amp he used a DC restorer zener circuit to stablize the voltage drop from tubes driven close to cut-off at high output demands. "This circuit 'zener is connected to the cathode bias resisterand fed back to the grids such that thegrid bias is held at a constant voltage (Carvers used 12volts) thereby restoringthe lost DC component of thedrive signal." His words.

kingfisher
 
its a simple auto bias circuit. so the amp doesn't run in class B

on another note if someone expands on the circuit say with a ccs the auto bias circuit would have enough gain in essence to trnsform the final stage into a local AGC keyed VCA and compress the signal.
 

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