DC solvers for triodes

A collection of DC solvers for circuits based on triodes ECC81-82-83-88 (for this Web tool) and many more plus models created by yourself in the PC app

November 2022 – download PC app V1.7

The new Windows PC application now offers 23 solvers, including 2 and 3-stage basic amplifier coupled by their RC filters in the power supply line, plus 3 circuits (cascode based after “Aikido” preamp, phono preamp, push-pull with DC feedback) designed by John Broskie in https://www.tubecad.com

Download the application for Windows PC

Usage stats

Since January 2020, you performed more than 26 000 actions. The most activated solvers are always the gain stage +DC-coupled cathode follower (C4) and the very basic gain stage (C1).

See Usage stats. Stats are available too in the PC app.

Web resources

Among the many web sites (there was a lot to my surprise) I visited by fall 2019, I found particularly interesting these links

My contribution: a collection of triode solvers for DC bias

This web site and the PC application are my contribution to the “tube community”, offering a set of solvers able to compute the operating points (DC bias) of the basic low-level circuits that are found in all tube amplifiers: gain stage, cascode, cathode follower, phase inverter, etc.

I programmed them for people who already are aware of tube design but who may feel uncomfortable with true simulation Spice-tools. One solver is needed per circuit. Luckily, the small number of circuits variants allows this simpler approach.

They are not perfect, they are in no case real circuits, and I am not liable for any wrong designs you may create after them! And never forget that playing with tubes is very dangerous because of the required high voltages!

Norman Koren’s modeling

All solvers use the modelling of triodes proposed by Norman Koren in the 2000’s, as described in http://www.normankoren.com/Audio/Tubemodspice_article.html taking advantage of his “new equations” and the parameters he indicates for the triodes 6DG8 (ECC88), 12AU7 (ECC82) and 12AX7 (ECC83). For other tubes, I took parameters from Spice models found on the Web.

I had also considered other models proposed by Dempwolf und Zölzer and Cohen and Hélie which take into account grid current. But as basic stages normally do not operate with grid currents, I decided to not implement them; in addition, my understanding is that they are based on very little experimental data (only ECC83), and one of them was simply not implementable because of a non documented parameter.

Contact me at tubes @ astefo.com