**how I get tube spice models**
How did you do the model ?

Tekko :

I am not sure exactly what aspect of "doing the model" you mean, and maybe the question was for Steen and not me, so I hope I am not going off on a tangent here.

There are two basic ways you can add models.

1) Use models that are already written. Do a web search for tube spice models. Or do a search in this forum for tube spice models. Or go to

WWW.DuncanAmps.com and look there.

2) Use an existing model type but supply your own parameters to match the particular tube you want.

Now if you absolutely want to use the Circuitmaker 2000 model that has been described here, then fine, but there are much better models out there. For models I do now I use Koren's model for plate current and Rydel's model for grid current, when I have data for grid current. Check out

http://digilander.libero.it/paeng/spice_models_for_vacuum_tubes.htm
and

http://www.normankoren.com/Audio/Tubemodspice_article.html
for more detailed information

Having decided on a model type, you need tube data to fit. You must either use data sheets or measure your own tubes.

For data sheets you can use a web search engine, use hard copy data books, or the best thing in my opinion is go to

www.DuncanAmps.com again and use his Tube Data Sheet Locator. It has links to all the other best known tube data sites. If the TDSL doesnt point you to a data sheet then there probably is not one on the web. I got the downloadable version of TDSL years ago, and get the updates regularly, and I dont see how I could get along without it.

The best is to measure your own tubes, assuming you have the tube, and you can rig up a power supply and some meters. How you do it is up to you. If that is beyond what you want to do, then fine, use the data sheets. I measure my own, but use the

data sheets to check that the tube I am using is at least fairly typical, and to get the values of interelectrode capacitance, since I do not have a capacitance meter.

Now that you have tube data one way or the other, you must adjust the tube model parameters to fit the tube data. This may have been the real point of your question, and I apologize if the previous discussion was not required.

There are 3 methods of determining parameters

A) mathematically based on a few data points, applies only to simple models, such as the CircuitMaker one. The formulas for doing this are algebraically derived from the model equations.

B) manually adjust parameters, run the model, check results, adjust parameters, repeating until no further improvement is found. Method A) can be used to get the initial parameters. Some model types lend themselves to this approach more than

others. This is what I did with DuncanAmps generic model back when I used it.

C) use a computer program, for example an Excel spreadsheet, to calculate the model parameters that produce the best match between the real data and the data predicted by the model. This is what I do with Koren's model, which in my opinion has too any variables to tweak manually, although I think some people may do it that way with Koren's.

Note that you can do C) with simple models as well, and get a "best" fit in the computer's opinion, but in my view you are just as well off getting a "best" fit at a couple of points that you pick.

In my view method C) with Koren's equation and tube data you measure yourself is the most accurate way.

I have left out the details of how to actually do A), B) or C) since I not sure if that is what you want. Let me know if you do need more details.