Simplistic NJFET RIAA

[Gigant]

in case an image didn't upload: B308-C1-E3-C64-E-4-DE8-AB3-E-6613-B5-C3241-F — ImgBB

 

[Salas]

so i should remove R1 & R14 and install Rx1 400R and set the jumper on S1 correct?

No, you will remove nothing. You will add RX1 400R (390R-430R acceptable). And a jumper across front left and right pads of S1.

 

[Oracle1]

About R1 & R14 is it ok? 71-S102C47K000BB (47k)

 

[Salas]

Most excellent but very expensive. Alternatively a Dale 47.5k 0.1% 5ppm 125mW is very good and much cheaper for R1: 71-PTF5647K500BZEK

For R14 in FSP or R17 in UFSP (R1 also if preferring to use same type) TE connectivity 47k 0.1% 15ppm 250mW Holco: 279-H847KBYA

 

[Gigant]

do i need a Z-foil for 400R resistor or any will do? Thanks

No, you will remove nothing. You will add RX1 400R (390R-430R acceptable). And a jumper across front left and right pads of S1.

 

[Salas]

Typically any will do but people usually put the best quality cartridge load resistor they can.

 

[Gigant]

Understood, Z-foil it is then, just to match the other two ;> Thanks

 

[Gigant]

Finally, after hours of fiddling, got the bias right! Will let the music spin for a while now ;> Thanks for all your support!

No, you will remove nothing. You will add RX1 400R (390R-430R acceptable). And a jumper across front left and right pads of S1.

 

[Salas]

You replaced the problematic trimmer with a fixed resistor and also put a normal quality Rx1 load resistor for now?

 

[Gigant]

Problematic trimmer with a working one but slightly bigger T93YA, also Rx1 cheapo 390 ohm (for now) and was able to bias after that. Will update you on how it sounds. Have to fine tune Denon 103 now. Cheers

 

[Gigant]

i have also shunted S1 left/right pin.

 

[Oracle1]

Goodmorning, one friend of mine has a NOS vishay RAK1 47.5k is it good?
(0.01%, 5ppm)
About R17?

 

[Salas]

47.5k can be R1 no problem. Because R17 is the base Riaa filter section's impedance it will slightly lift deep bass if not 47k but 47.5k unless you might like that. Sfernice wire-wound RAK1 quality is very good as a part itself.

 

[Salas]

i have also shunted S1 left/right pin.

If you measure at the input RCA with the Ohm meter (phono power must be off and no input cable attached) what value you see? About 387 Ohm? If yes, all is done well.

 

[Gigant]

will test that later in the eve after work, thanks

If you measure at the input RCA with the Ohm meter (phono power must be off and no input cable attached) what value you see? About 387 Ohm? If yes, all is done well.

 

[Gigant]

Measured inputs: 384 & 385 ohm respectively. Must be ok. Thanks

If you measure at the input RCA with the Ohm meter (phono power must be off and no input cable attached) what value you see? About 387 Ohm? If yes, all is done well.

 

[Salas]

Yes its ok. Numbers reading within tolerance of DMM and resistors %.

 

[Gigant]

THANK YOU Mr Salas, it's a pleasure having such a musical phono! Respect is burning

Yes its ok. Numbers reading within tolerance of DMM and resistors %.

 

[Hicoco]

Put around 400R in the Rx1 slot for a regular 40 Ohm DL103 model.

Hi Salas, just curious......the Denon 103 cartridge have 40 Ohm output impedance for 0.3mV output voltage. Why did you recommend 400R (Rx1) // with the 47k (R1).??

 

[Salas]

To have about 10:1 load impedance to source impedance ratio. So not to lose any cartridge signal potential. That's technically sufficient. Unless other factors exist.

Note:
We usually read various load recommendations for MC cartridges. Many times conflicting. One likes 100 Ohm loading and another one 1000 Ohm for the same model. Others like everything in between for it.
I suspect everyone is right and their difference isn't what the cartridge asks for, but with what resistive damping the same cartridge + their different phonos behave best for ultrasonic peaking. Classic integrated Japanese phono stages with strong negative feedback loop tended to 100 Ohm with most MC carts for instance.