UNSET pentode for voltage amplification

[zintolo]

@Tubelab_com would you consider testing a nfb circuit if I send you a populated pcb?

 

[grataku]

Growing up in Cuba everything tech related was a challenge, I had to borrow soldering gun, multimeter etc from a neighbour who repaired radios and TVs.

No worries. You listen to the old Victrola with WE 555 and field coil woofers and you quickly realize that everything worth discovering in audio was discovered between 1900-1940.

 

[jcalvarez]

Update. At last I put everything together on the bench. I'm not completely happy with the result, the distortion figures are way higher than the simulation (no surprises here I guess...), on the other hand the circuit can drive ~52Vrms, input 1.54Vrms, onto a 10K load, with 1% THD. I also noted I was wrongly getting the output from the plate instead of top mosfet's source. Below measurements with 3 different output levels (13,26 &52Vrms), at 250V Va with CCS set to 9mA. Tried 5 NOS EF184, they were pretty close to each other. My environment is very noisy, the moment the sound card's input get connected to the bench the noise goes up a lot. Need to try with a laptop, away from my PC.


The bench