EL34 Push-Pull 5

Schematic by Charles P. Boegli (April 1961). Power 50W.
This schematic uses a global negative feedback but also a positive feedback including the stages 2 and 3.

Amplifier adjustments:

1. set the 5M potentiometer to its mid-point
2. disconnect the final stage and connect the neon lamp
3. adjust the 5M potentiometer until the beginning of an oscillation is visible at the neon
4. reconnect the final stage and disconnect the neon
5. adjust the current in each final tube to 50mA
6. after a month, check and readjust this value to 50mA

Amplifier & Power Supply

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