Vermes
Advanced Member level 4
Presented here amplifier is a typial Single Ended based on EL34 in the power stage operating in triode and pentode mode (selected by a switch) and ECC82 in the preamplifier operating as White follower, EM84 as a meter and EAA91 as a signal rectifier for tubes EM84. The amplifier is equipped with a semiconductor rectifier bridge for anode voltage. There is a CLC filter for the power amplifier and CLCRC filter for the preamplifier. Total capacitance of capacitors for anode voltage is equal 362uF. That capacitance is sufficient because the only hum is a result of magnetic coupling between the speaker and mains transformers. Choke has 8,1H and 140mA of permissible current, 20mA reserve. Anode voltage on the first electrolyte is 270V and approximately 245V on anode of EL34. Ug1= -14,5V.
Initially the amplifier was powered from stabilizer power supply from Elpo, and later it was changed to mains transformer.
Pictures of the amplifier:
Pictures of construction:
Those schematics needed to be modified (e.g. adding triode/pentode switch):
Link to original thread - Prezentacja mojego wzmacniacza lampowego SE EL34
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