Simplistic NJFET RIAA

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Joined 2006
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Well considering the Neuman cutting lathe to be the best, maybe we could think about including one more node at 50Khz in the riaa circuit. Maybe we could finally use a higher value 16n and not loose the high freq magical touch because we would be increasing amplification at 50Khz.

Nevertheless i believe this iRIAA is not suitable to finetune our "pure" Lipshitz layout because it is based in a different circuit.

Reading about the iRIAA made me realize it is a passive filter so it is as difficult to determine the correct component values as we have here... so why should we take for granted that it is the ultimate reference ?
 
diyAudio Chief Moderator
Joined 2002
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I have also made it with an extra resistor in line with the 16n HF riaa cap once. So to comply with extra cutting lathe compensation. I have done so in the Valve itch phono too. I took em out. It did not work to my taste. Thats how it is done if you wanna try in your system and to your taste.
 

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diyAudio Chief Moderator
Joined 2002
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I don't know, there have been articles about it considered a must, others arguing against. I just put it in my phono and in my system, if it does not work for me can be exciting my tweeter's oil can resonance, or something not well frequency compensated in my amp, who knows. Or it can be too much in general. I just talk my narrow experience, can't make or support claims. Beyond scope of personal DIY anyway. You should try it one time to see for your self. About inductive Riaa ready made and screened networks I don't know if they now have it, haven't looked. Those are normally driven by low impedance, I don't think you can just drop em in here.
 
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I was not thinking of droping some coils into the Simplistic..... I am not a wizard like you... And besides that I would not tamper with your work.... What I wanted to know is if someone building a riaa bazed on coils would benefit from using Hagerman iRIAA to finetune :)

Just for the fun I made a graph demonstrating the effect the extra resistor makes on the Lipshitz setup.
From 1KHz to 12.500Hz it reduces gain (relative to Lipshitz)... after that it starts to increase gain dramatically.

At 50kHz the Hagerman circuit amplifies more 2.8dB than the Lipshitz.

In the attached image, imagine the 0dB line to be the Lipshitz curve (I straitened it only to better show the effect)
 

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