• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube-cad, is it worth the $40?

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Is the tube cad program worth it?
Yes. I've got Tubecad, SEAmpCAD and the PPAmpCAD.
Does it come with a good data base?
It has the most commonly used audio tubes. Remember, in terms of sales, the world audio tube market is dominated by the 12AX7, and a handful of power pentodes. I build instrument amps now, and straying from the known isn't really acceptable commercially, except in a bespoke/boutique environment, and only then sometimes. So it's a useful tool to check things out in my case. Other oddball tubes I can get a good idea of performance from eyeballing the curves and making some guesses.
Can you actualky use it for design or is it just a learning tool
Yes to both. But it's only a single stage design program. That's not at all a limitation to me as design this way anyhow.

I'm a big fan of John Broskie and his site and I like to support it. All the programs I've bought are useful to me.

I've been thinking of purchasing SE Amp CAD but was wondering- does TubeCAD itself did not do SE? If I want to play with designing both SE and P-P amps do I need both programs?

I only wish they could do two stage designs but since I'm a total newbie at designing my own circuits maybe that isn't really a problem?
I'll second what Brett said. I'd get all three if you want to do both SE and PP designs. Tube CAD is mostly for designing pre-amp stages and drivers. Yes, the topologies covered can be used for output stages, but it doesn't include transformers. Likewise SE is for output stages. SE has a selection of transformers and tubes commonly used for output stages and can pretty much do a final design of the stage. I don't have PP, but I assume that it is analogous to SE.

The programs are a very nice learning tool, as you can play with values and see how that changes the output; voltage swing, distortion, gain, etc..

TubeCAD is not the absolute simulation program. It can be very useful for grossly checking a circuit idea, with a very good accuracy, also for trying various circuit topologies and see how they fit for a certain purpose.

Finally, marcfleischman, since you are new to tubes, this program would be very helpful for understanding the operation of the various circiuits.
A different option

I bought Tubecad some time ago with the hope to learn more about tubes and amplifier design. Just a few days after I order TubeCad, I discovered Microcap Simulation software. This is a simulation software that allows you to tweak around a tube circuit and even a simple tube amplifier (evaluation version is limited to around 50 nodes or so). You get the DC operation points, AC response, transient, distortion and much more that I haven´t checked yet. It comes with a database of general components and also popular tubes spice models.
You can analyze preamplifiers, push-pull, SE, etc.
Just by the fact that Microcap evaluation version is free, my advise is that you download it and play around before decide to pay for tubeCad.
Joined 2004
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I second that, definitely take a look at the MCAP 8 demo version, you will have to enable the tube models but that is easy to do. Most SE amplifiers and some PP types can be realized at well under the 50 node limit. I now use LTSpice instead, (Linear Tech) but installing tube libraries in this program is a bit of an undertaking. It has no node limits and like mcap is free, but far more powerful. You can also add various other models in 3F4 and berkely spice without any problems.

Joined 2004
Paid Member
In the tool bar open windows, select component editor, click on analog library, then tubes, and you will see pentode and triode selections.
Open the tube type you want to make active, select definition Subckt and then assign A for plate, G for grid, K for cathode and S for screen in the case of a tetrode or pentode, just AGK for a triode. Exit the editor and when prompted save the changes..

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