Simplistic NJFET RIAA

[merlin el mago]

EB do a Phono with fets with a gain of 73dBs, only a master can do

[Salas]

Does he give its noise density?

[merlin el mago]

Ricardo,

Please note in bolt:

Originally Posted by RCruz

Are these the real values on your build ? I wish you had made pairs before soldering.
I also need to know the real 3k3 value.

Admiting 3k3 = 3k3 sharp, in the Left channel you can // 1M5R5-1M13 to 47k and 300p // 47n......you will be very close to heaven.

Now the other channel is bad.... the main problem is 6k9 R4-6K79that should go down to 6k77 .... You will gain lots of presence that way in this channel. Also I would go for 1M7 // 46k8 and 300p // 47n.

All this with 15.6n // 330p as initially.

Now it would really be good to have both channels with the same values... do you have more resistors so you can make equivalent pairs ?

Regards
Ricardo

Yes these are mine real values, unfortunately I trusted in Pcx because I have ordered & paid matched pairs.

So it's not necessary 68pF to reach the 16nF for C3, I will remove in both channels?

Tomorrow I will let you know exact values of R1.

Not I haven't got more resistors I have to order more, please be sure with values as you know this kind of resistors are expensives, thks.

[merlin el mago]

Originally Posted by Salas

Does he give its noise density?

From data-sheet Erno Borbely Web:

Circuit description.
The schematic of the EB-199/320 is shown in fig. 2. The first amplifier is a linear one, using 4 pairs of low-noise Cascoded JFETs at the input. The second stage is also made up of low-noise Cascoded JFETs. The output stage is a complementary MOSFET source follower. The gain can be changed with the feedback resistors to 20, 30, 40 and 49dB. R28-C15 provides the high frequency roll-off of the RIAA equalization.
The second amp provides the bass boost of the RIAA curve. Except for the input stage, which is a complementary differential Cascode circuit, the amplifier has the same topology as the input stage. The second amp has a gain of 24 dB at 1 kHz, making a total gain of 54 and 64-73 dB for the phono preamp.
Due to the high gain at low frequencies (64-93dB!), both stages are using servo control for DC-offset. The offset control is provided by low-noise JFET-input opamps. The opamps are supplied with ±10V from shunt regulators

Typical Specifications.
Gain: 1st stage: 20, 30, 40 or 49dB (20dB for MM)
2nd stage : 24dB
THD 3VRMS/1kHz: 0.002%
Max. Output voltage: approx. 9VRMS
Risetime (without RIAA network): 0.3/0.4usec
RIAA Accuracy: better than 0.2dB
Equivalent input noise: <100nV, 20Hz-30kHz

Secret questions ask directly to Erno, but for sure don't tell you, I'm sure that the real Merlin The Wizard is Erno & his magic.

[merlin el mago]

Originally Posted by RCruz

Come on Merlin.... I need your feedback !

My new riaa might be exactly like yours so I must learn a lot now.

Sorry I'm the only learning here. You know a lot of more than me.

[Salas]

I would go with bipolar low rbb head amp if I had a 0.1mV cart, still.

[merlin el mago]

I would prefer hear both face to face & after I will take mine decission.

Still have the Linn Arkiv 0.16mV, but I see very complicated the designs of Syn8 & Gerard Mpp project seems never finishing.

[merlin el mago]

Ricardo,

I have a couple of Shinkohs 999K 2W, also I have a couple of Caddocks MK132 one 1,002Meg & the other 1,001Meg, wich of both will be better for R5?

[merlin el mago]

Originally Posted by Salas

Of course. And when Merlin starts designing and becomes famous then we will have the first with 3 letter acronym or more.

MEM or MTW?

[Salas]

Mem de CB