This is the circuit diagram of 35W Tube Power Amplifier with EL34. This tube amplifier designed in 1953 and worked from 1954 until 1989. If you’re interested with classic circuit and classic components, then you should try this circuit. The circuit is interesting but i think it is hard to find the tubes.
|R1 = 470K 0,5W||R13-21 = 820K 0.5W||C8-9 = 0.1uF 630V|
|R2-5 = 2K2 0.5W||R14-22 = 5K6? 0.5W||C10-14 = 0.47uF 630V|
|R3 = 150K 0.5W||R15-20 = 680K 0.5W||C11-13 = 25uF 40V|
|R4 = 220K 0.5W||R16-19 = 100K 0.5W||V1 = E80CC|
|R6-10 = 56K 0.5W||R17-18 = 3K3 1W||V2 = E80CC|
|R7 = 3.9K 0.5W||R24 = 470R? 2W||V3-4 = EL34|
|R8 = 220R? 0.5W||TR1-2 = 470R? 1W Variable (adj. 270O)||Rectifier tube =?Z2C|
|R9 = 1M? 0.5W||C1-3-6-7 = 0.1uf 630V||T1 = Audio Transformer for 2x EL34 Push Pull|
|R11 = 39K 1W||C2 = 220pF 600v|
|R12-23 = 180K 0.5W||C4-5 = 16uF 550V|
It is a classic design of power amplifier 35 W using tube, with two EL34 in connection Push-Pull, by Siemens & Halske, with design date 03/24/1953 and code SV410 / 1. The amplifier worked from 1954 to 1989, whenever and went off, with an average lifespan of 15 hours a day. Showed no particular damage beyond the replacement tubes, resistors and capacitors, resulting from natural wear.
A significant change was the replacement of the rectifier device of lamp diodes. The only problem will be for those who try their construction, will be the output transformer (applies to all tube manufactures), because the code is not helpful. Can be replaced with a conventional output transformer suitable for EL34. During the construction, it is need (applies to all circuits respectively) enough electronic experience and attention to the high voltage, electric shock risk.