Push Pull Output Valves - Mic Pre - LTspice Models - Koren Lib

Hey guys,

Finally, I had some free time this Sunday  ;D

After improving on my LTspice modeling while using the koren library for the tubes I managed to amplify a mic level signal through the  2 triodes of a 12au7 in which the gain is controlled by feedback. I had to experiment with the cathode, grid, and plate resistors but the input stage seems to amplify well according to the sim, B+ is 300VDC. Now the push pull section isn't as easy to model because I'm not sure how to set up LTspice for the output transformer and pentodes.

*edit - to anyone who read this earlier I ditched the phase splitter and went directly from the cathode bias triodes to a self splitting push pull output topology

Any advice would be appreciated.

All the best,

It seems like a lot of the G3 pins (suppressor grids) are missing on the pentodes in the koren lib. for LTspice.. I'm wondering if maybe they are programmed to simulate as being locked to the cathodes? Maybe the lib is only designed for running the pentodes in triode mode?

Here are some examples of the models:
********************************************************************************************
.SUBCKT EF86  1 2 3 4 ; A G2 G1 C (Pentode)
* Philips data sheet AKA 6CF8 and 6267 Z729 EF806
* library format: LTSpice 02-Jun-2008
X1 1 2 3 4 PENTODE1 MU=34.90 EX=1.350 KG1=2648.1 KG2=4500 KP=222.06 KVB=4.7 VCT=0.00 RGI=2000 CCG=4.3p CPG1=0.6p CCP=5.1p ;
.ENDS    EF86

********************************************************************************************
.SUBCKT  6267 1 2 3 4 ; A G2 G1 C (Pentode)
*  same as EF86
X1 1 2 3 4 EF86
.ENDS 6267
********************************************************************************************

Donde es G3?

Whenever I try to run the sim I get a count mismatch between the definition of the subcircuit error prompt

then it says - instance: xu3

deleting the cathode to suppressor grid connection gave me the same error

Maybe I should switch to the duncan libraries..

this might explain it

from the text file
"modified pentode models to work with native LTspice Tetrode symbols."

I'm still wondering why it's done this way

buildafriend said:

this might explain it

from the text file
"modified pentode models to work with native LTspice Tetrode symbols."

I'm still wondering why it's done this way

Click to expand...

Because there are no data in the datasheets regarding G3 modulation.