Circuit of RIIA phono pre-amplifier with op-27. The op-27 is used in that circuit as phono pre-amplifier for your characteristic of low noise.
He only contributes with 3.2nV/√HZ of noise tension and 0.45pA/√HZ of current noise to the circuit. To minimize the noise of other sources, R3 it is configured for 100©. That generates tension of noise additional of only 1.3nV/√HZ. R1, R2, c1, and c @ form a net RIAA of a lot of precision with standard components supplying the necessary constant of time of 3180, 318 and 75µsec. For initial equalization and stability, resistors metal-film and capacitors of film of polystyrene or polypropylene are recommended.
Filter Circuit of RIIA phono pre-amplifier op-27
Capacitor C3 and resistor R4 shape a simple filter of -6dB for octave, with cut to 22Hz. That circuit is capable of very low distortion on the entrance sign, usually below 0.01%. To 3v of total harmonic exit produced distortion is smaller than 0.03% in the frequencies above 20KHZ.
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Hello, I realized this circuit and the audio is terrible like within a box, I did the simulation in eagle of the riia filters and they seems all bad, with your filter the curve are all in the highs, indeed with the correct circuits the audio are more open on the hight. Please recheck the circuits o remove it since is not correct in my opinion. I can send the ghraps fron spice if you need it for double checking. Your circuit is strange shoud be two rc circuit in parallel in the reaction circuits 6/2 indeed there is sone strange connections, that really doesn not understand and nor spice does.