• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

RIAA with 4 common tubes

I adapted an old circuit using 4 common tubes, what do you think about it?
 

Attachments

  • Riaa ECC82 ECC81 schem.JPG
    Riaa ECC82 ECC81 schem.JPG
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  • Riaa ECC82 ECC81 scope.JPG
    Riaa ECC82 ECC81 scope.JPG
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Provided that Microcap's results are true (I have several doubts), there are two issues I would like to understand first:
1) Whether to place the voltage gain stage downstream or upstream.
2) What types of caps to use (apart from the usual decoupling and bypass caps).
 
Perhaps you can simplify a lot by using a passive RIAA and 2x6EM7 per channel for the amplification stages and also have a medium-low output impedance without having to use a CF. What do you think about?
 

Attachments

  • 6EM7 6EM7 passive RIAA schema.JPG
    6EM7 6EM7 passive RIAA schema.JPG
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  • 6EM7 6EM7 passive RIAA curva.JPG
    6EM7 6EM7 passive RIAA curva.JPG
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