Simplistic NJFET RIAA

[merlin el mago]

@Salas
I heard the left channel with less gain so come back to measurements:

(R=right channel & L=left channel)
Leds/GND 7,22V(R) 7,24V(L)
R17 across 293mV(R) 278mV(L)
R10/Q2 to GND 9,94V (left channel changing values from 10V to 0,49V & when is low value the leds don't lit or shine less) it's possible Q2 damaged?
R1/Q3 to GND 12,24V(R) 12,08 (L)
R7/GND 10V both channels
Drain Q5 to GND 22,4V(R) 22,3V

Regulators current:
Right 415mA
Left 418mA

Thank in advance for kind help

[merlin el mago]

@Salas
To adjust balance between channels I want to change fixed resistor R2 15R for Vishay 1280G trimming potentiometers .75W, 15ppm, wich value will be enough: 20R, 50R?



These two 5K are both for SSSLWR (super simplistic Salas low voltage regulator)

[Salas]

Link me to the specific schematic, I can't remember by designations.

[merlin el mago]

Simplistic NJFET RIAA

[merlin el mago]

Simplistic NJFET RIAA

[merlin el mago]

Reg. is with remote sense V1.0

[Salas]

Thanks, now I see. First change Q2. I don't like it shows different voltages. Maybe got some damage. If it will not match well after that for RMS out between channels, change both R6 for 50R trimmers and then you will be able to trim the gain. Stay over 27 Ohm.

[DualTriode]

Originally Posted by Salas

If they are genuine items we can design for GR when not looking for top gain and MM lends for that. Try your hand on this one. Use an LM317 reg firstly just to see if the FETs behave as expected for gain & low noise. The 100k input load trimmer connected as a rheostat will let you calibrate tone, since the omnipresent 47k load for MM is a myth.

Hello Salas
I am in.
A personalized CCT and all. I am off to check my parts bins and match some pairs.
Thanks for the light.
DT
All just for fun!

[merlin el mago]

Originally Posted by Salas

Thanks, now I see. First change Q2. I don't like it shows different voltages. Maybe got some damage. If it will not match well after that for RMS out between channels, change both R6 for 50R trimmers and then you will be able to trim the gain. Stay over 27 Ohm.

Ok I will change Q2, I have just installed following your advice 50R trimmers (now I installed Vishay 1280G 15ppm ) I will stay over 27 ohms, I will let you know, thank you.

[merlin el mago]

@Salas
I have these dual LSK389BL:

10,65 / 10,75
10,68 / 10,84
10,05 / 10,27
11,15 / 10,72
10,20 / 9,97
11,15 / 10,90
10,78 / 10,64

Wich one will be better to change damaged for 10,50 Idss?