Simplistic NJFET RIAA

[Joao@AltheaMusica]

@ Merlin:
Wich others? > all the professional designers out there are using it.

@ Caro Ricardo
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 ?
I don't know how Jim Hagerman is doing it. There is an exactly measuring rule to do check this:
Build a low impedance Inverse RIAA - 600 Ohms for example - and insert it between the signal generator and the phono stage input. Measure the amplitude frequency response. If your curve RIAA network is correct you must get a proper frequence response.

That's the theory. Sonical the result can be "adjusted" like you all know... I agree that not all discs are cutted with that 50khz drop off but that's live.

[RCruz]

Would you share the reasoning behind the resistor value.... why 200r ?

[Salas]

Creates a compatible zero rectifying the droop when driven with the extra pole. Just EQ.

[merlin el mago]

Hey guys, interesting exchange of ideas about RIAA

[massimo]

No Inter vs. Barca in Madrid.... we'll stop in Barcellona.

[merlin el mago]

Now 2 Tx + 2 PSU in one box & Phono RIAA using 2 Regs in other box.

Subjetive impressions: more gain, more separation between channels, etc., are far better than using 1 reg & 1 Tx.

Next step "remote sensing".

[merlin el mago]

Originally Posted by massimo

No Inter vs. Barca in Madrid.... we'll stop in Barcellona.

Who knows, in Madrid no, but is possible Inter plays & wins the Champions League, why not?

[RCruz]

Originally Posted by merlin el mago

Now 2 Tx + 2 PSU in one box & Phono RIAA using 2 Regs in other box.

Subjetive impressions: more gain, more separation between channels, etc., are far better than using 1 reg & 1 Tx.

Next step "remote sensing".

Now you´r talking

[RCruz]

Originally Posted by Joao@AltheaMusica

@ Merlin:
> all the professional designers out there are using it.

@ Caro Ricardo

I don't know how Jim Hagerman is doing it. There is an exactly measuring rule to do check this:
Build a low impedance Inverse RIAA - 600 Ohms for example - and insert it between the signal generator and the phono stage input. Measure the amplitude frequency response. If your curve RIAA network is correct you must get a proper frequence response.

That's the theory. Sonical the result can be "adjusted" like you all know... I agree that not all discs are cutted with that 50khz drop off but that's live.

Would you give me a hint about one or two OEM phono preamps that actually use a 4rth pole in the 50kHz ? Today I am atending another Audio Fair and would like to know.

Do you mean that building a low impedance iRIAA is more acurate than building the RIAA itself ?

I am strugling to reach the optimum curve but it seems there are many ways to reach Rome.....

[RCruz]

Originally Posted by Salas

Creates a compatible zero rectifying the droop when driven with the extra pole. Just EQ.

I believe I got the math behind it already.... I will ask your opinion latter.