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Simplistic NJFET RIAA
Simplistic NJFET RIAA
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Old 18th March 2010, 10:42 AM   #3371
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by Joao@AltheaMusica View Post
Boa tarde

you guys are to fast for me. Yes Merlin, for example like Jim Hagerman - or others - are doing it.

Have a nice day!!!
Wich others?
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Old 18th March 2010, 04:02 PM   #3372
RCruz is offline RCruz  Switzerland
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Simplistic NJFET RIAA
Quote:
Originally Posted by Joao@AltheaMusica View Post
Boa tarde

you guys are to fast for me. Yes Merlin, for example like Jim Hagerman - or others - are doing it.

Have a nice day!!!
Ol Joo

How do you think Jim builds and tests his iRIAA ?

The best way to test a iRIAA is certanly the use of a propperly setup RIAA no ?
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Old 18th March 2010, 04:06 PM   #3373
Salas is offline Salas  Greece
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Hag's has extra hf cutting head compensation mind you. 50kHz? Here I feed Lipshitz pre emphasis in my sim.
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Old 18th March 2010, 05:46 PM   #3374
RCruz is offline RCruz  Switzerland
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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 ?
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Old 18th March 2010, 06:05 PM   #3375
Salas is offline Salas  Greece
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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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Old 18th March 2010, 06:10 PM   #3376
RCruz is offline RCruz  Switzerland
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I agree with you !

Also, I do not know if every disc is cutted with that 50khz drop off.

Do you know if the coil based riaa circuits have this node in consideration ?

Last edited by RCruz; 18th March 2010 at 06:14 PM.
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Old 18th March 2010, 06:20 PM   #3377
Salas is offline Salas  Greece
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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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Old 18th March 2010, 07:00 PM   #3378
RCruz is offline RCruz  Switzerland
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Adding the 200r in my Spice circuit.....

Last edited by RCruz; 18th March 2010 at 07:06 PM.
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Old 19th March 2010, 12:11 AM   #3379
RCruz is offline RCruz  Switzerland
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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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Old 19th March 2010, 12:48 AM   #3380
Salas is offline Salas  Greece
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That is what it is supposed to do, given that there should have been original supersonic energy in the record's groove, lost by the lathe's driving cut off. If you want to experiment for restoring that constant, you need use that resistor.
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