Needs some education - Phase splitter clipping

[IvesH]

Hi all, first thanks for helping me out with the phase splitter here in this thread

I was super enthusiast that I got the phase-splitter output swing going to ~35Vpp to drive the output tubes. Now I re-connected the negative feedback and the amplification factor from the first stage pentode dropped from x40 without NFB to x13 with.

And now I do not reach what I wanted on the output tubes / phase splitter
At 2Vpp in Pin 9 gets 26Vpp and Pin 1 has 24 Vpp
The NFB Signal on Pin 3 and 7 is 1.6Vpp

So is this to much ? Normal ? Any suggestion on improving the balance between amplification and negative feedback correction with the 10K resistor? I could add an extra tube stage but that I do not see in other similar simple diagrams and would like to avoid that.

I started a new thread here, https://www.diyaudio.com/forums/tubes-valves/367962-education-negative-feedback.html#post6536098

 

[gorgon53]

Hi guys and girls success as an easy test I biassed the phase splitter Grid at 86 v with a voltage divider to the 350 V (left the coupling capacitor) and re-used the existing 220K to ground on the board. Pin 1 is now 257 V and Pin 8 92 V DC ~ 2.5 mA through the tridode.

Max output swing is now somewhere between +-33 and +-36 V on pin 1 before clipping 🙂 Following Depanatoru rule of thumb this looks quite ok. Very happy.
A 2 cent resistor brought my output power from 5 W RMS to 25W RMS (little dance here)
Thank you all! Feedback and hints still welcome, going to test later today the direct coupling.

Get rid of that cap and voltage divider and dc couple instead (you do not want to introduce 1 more pole with fb)
you have been told already by someone how to do it proper, why do you ignore his good advice?

 

[IvesH]

Not ignoring the suggestions at all, just learning and testing, rebuild with direct coupling is on the way.

 

[nigelwright7557]

Get rid of that cap and voltage divider and dc couple instead (you do not want to introduce 1 more pole with fb)
you have been told already by someone how to do it proper, why do you ignore his good advice?

As my ex wife would say "Have you ever tried to get a bloke to do as he was told?" "He always knows better."

I explained how a phase splitter worked way back.