Stringsandfrets DCCF harmonics

[Cannibal]

Hello everybody,

I've just read the articles published on stringsandfrets relative to tuning the harmonics balance of a DC coupled cathode follower and found it very interesting: out of curiosity I've simulated the same circuiti with LT spice but my results do not agree with their results, the fault being that my LTspice 12AX7 models draw grid current in a "funny" way. My question is: anybody knows which tube models do they use in their simulation?

Here the link to the article (great read):
https://sites.google.com/site/stringsan ... -harmonics

[Tony Bones]

If you go to the Welcome page of that site, there's a line near the bottom that reads:

"email for comments or questions: uneumann at gmail dot com"

[Murrayatuptown]

Ulrich sent me a file for a rabbit-hole project, and he included three different tube models, with the suggestion (my wording at this point) I could 'comment out' two and activate one. That way I could compare all three.

Which is real? Who know?...they're models
...helpful but not gospel. I get the impression one has to take tube model simulation with some perspective...apparently one model may not be foolproof for everything from small signal to overdrive.

I'm on my phone right now so can't easily look. I have a question anyway on folder practices with LTspice. I broke something that should be simple but duh, I overcomplicate it.

I remember Koren, Kobayashi (or close spelling) and a generic-sounding name for the tube model libraries.

I have both Ulrich's books (and can actually find them!). If you have only access to his weg page details, I'll look thru both books. I suppose the GAO book is more relevant because it predates his hybrid phase.

There IS a DCCF in one of the Solo hybrid amps, but that may not your area of interest.

[Murrayatuptown]

I can type better than my last post!
I'd edit the gibberish but can't find an edit button...

[Murrayatuptown]

Tube include files were
TubeLib.inc
Koren_Tubes.inc
dh_Tubes.inc

[wpaulvogel]

I can’t speak for the spectrum analysis or LTSpice predictions but I can speak from experience and just built an amp featured in this forum, a single ended design and my DCCF reactions exactly as Merlin proves. Mine is set at about 700k grid stopper and compresses beautifully adding amazing harmonic content to the amp tone.
I chose this topology to use the compression for both harmonic content and more importantly for gain reduction. My output stage biases at -16 volts and I wanted a decent 12:00 setting for max clean output before onset of clipping. Squishing the second stage voltage swing was the only option I would allow to retain signal without voltage dividers.

[TUBEDUDE]

In theory, simulation and reality are the same. In reality it's different.

Sim is fine for estimation and setting basic
starting parameters/ conditions.
Then the breadboarding, soldering, parts replacement, circuit modification and testing makes it real.