6N11\6DJ8 chinese board mods

[indaco]

Hello, I have from last year this cheap preamp board:

Buffer 6N11/6DJ8 Tube SRPP Preamplifier Headphone Amplifier Board Preamp PCB DIY 699917213049 | eBay

Since I'm interested to a circuit possibly with a lower Z out (maybe good for driving later an amp stage or so), I wonder if it's possibile to modify it simply for a mu-follower circuit, I was thinking to something like this schematic here

 

[HHead]

I have this image on my PC as to diagram for 6N11/6DJ8 headphone preamp


As I remember from the board there is a small discrepancy in the wiring of the heater circiut, A divider is missing from the diagram which is 150k/50k from B+ to gnd with tsp going to one side of 6.3v

 

[indaco]

I have this image on my PC as to diagram for 6N11/6DJ8 headphone preamp


As I remember from the board there is a small discrepancy in the wiring of the heater circiut, A divider is missing from the diagram which is 150k/50k from B+ to gnd with tsp going to one side of 6.3v

Maybe do you mean a part is lacking about the heater elevation circuit for the SRPP upper tube?

 

[HHead]

The divider, not shown in schematic is tied to one side of the 6.3v for both tubes.

 

[indaco]

Another thing, I don't see the decoupling capacitor paralleled to 51K

 

[indaco]

Having a 6.3V C.T. I think it's possible to choose this solution and insert the voltage divider in the heater's PSU

 

[audiowize]

11dB isn't a hugely useful amount of gain in an amplifier, though the specs otherwise look quite nice.

 

[indaco]

I don't remember where the circuit coming from (I think Artosalo), then simulated with Ltspice. The question is how to adapt it to the chinese board, I leave in stand by