B250 PSU
Transformer for stereo 800W 2x50V AC, when using 3x2SC5200/2SA1943
On picture with 3x2SD1047/2SB817 was used transformer 600W 2x45V AC.
Probably any dual OP will work in this circuit. I mostly used TL072. OP amp work as AC buffer and DC servo in this circuit.
Regards
Still work on it, I probably need professional help to finish. I have over 200 project for 30 years of work.
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This circuit looks like some polish amplifier, custom-made in 1989-1990. Output power was 120, 140 or 200W, output made with triple BD139/40, BD285/6 and 2N3055, and THD < 0.3%. Your circuit is "much more Hi-Fi like", but the same output stage, op-amp on input, and no global feedback then, and even "DC-servo" is done the same way. I'll try to find schematic in electronic version and post link here. This circuit was wery interesting for me (no global feedback), and I want to know more about measurment on Your B500. Are there was done some, and can You post it? I'm interesting about THD and harmonic spectrum especialy. (and sorry for my bad english 😉 )
This polish amplifier is it quasi output? I have measurment only for THD<0,03%. This amplifier made for PA, and I considering to use this circuit for Hi-Fi (50W in another thread), but audiofiles don't like OP in input stage no meter if sounding beter than descrite.
Regards
Yes, quasi output. OP is not a big problem - You can replace it for example with some blameless-like circuit, or with whatever You like. I am mainly interesting output stage. I photographed schematic, and can e-mail if You want. Its readable 🙂, about 2.4MB.
I don't know what is "blameless" circuit. This circuit without global feedback based on OP amp, output stage is just ordinary emiter-follower. I have descrite input in my 100w Ultimate Fidelity Amplifier, but can't be modifited to work without global feedback.
Regards