SPICE Parameters of some EML Tubes

PX25 Spice
12B Spice (By Dr. Bernd Ahlswede, Germany)
20B Spice (by Roberto Penna, Italy).
300B Spice (by Ale Moglia, Italy)
300B-XLS Spice

Spice Parameters are used in simulation software. The most used software is LTspice, by Analog Devices. It is probabaly the most used simulation software. The "light" version is freeware, but already this version is extremely powerful. Their strategy is, to provide free spice parameters for their transistors and integrated circuits. But there is nothing against it, create your own spice parameters for your own components. Be it, an integrated circuit, a transformer, a transistor, and yes, also tubes. Just anything with wires on it.

Spice is not self explaining, but when you are a good engineer, you will quickly get used to it, because it's made by and for engineers, and it's not really difficult. Besides on the forums is given good support. It's just not, you install it, and right away you get some first results. Intially you need to learn how to make the circuit diagram with LT-Spice. When that is done, basically you need to connect a virtual signal to the input, press "Run" and you can see the signa, at any place of the circuit diagram, where you connect the virtual oscilloscope to.

So after installing this freeware, you do need to go through some of the internet tutorials first, and then try to set up something simple all by yourself, from the beginning. Best is a simple transistor amplifier in common emitter circuit. When you have that working, and you overcome all simple problems you initially could not solve, get ready for using transformers and tubes. Then, that step is only small.

For using a specific tube, you only need it's S-Parameter file as such. You can read it, because it's in Microsoft "text" version, but you don't need to know or understand the contents actually. With this file, LT-Spice can calculate the plate current, at any given grid voltage and plate voltage, also between two curves, and even construct missing curves at higher voltage, if these are missing.

Further below here, I will give you an idea of how it works, but it can not replace a tutorial.

How does SPICE work?

Spice is a virtual test set up. It begins with the REAL circuit diagram, which however you need to re-draw with LT-Spice drawing freeware. Actually these schematics look good. You do no need to get used to it a little bit. Once the schematic is in LT-Spice, the Spice program knows the components, and how the are connected. Now it can calculate the result. So for a resistor, it is easy. But for a tube, it needs to know the tube curves. S-Parameters are nothing else as a set of formulas, from which the tubes curves are calculated. So at a given plate voltage, and given grid voltage, you het the plate current. It's really only that, With that LT Spice can do it's job, and calculate the output signal of a circuit, when it knows the input signal. In Spice the input signal can be defined, and way you like it. Take a sine wave, or a frequency sweep, or create a circuit (in Spice!) which creates a signal. used by Spice itself. .

Then load the output with an 8 Ohms resistor, and at the "run" command, the amplifier works now as a simulation.

What is really nice about it, the program has virtual voltage probes and current probes, you can measure all signals, not just at the "output" but anywhere you like. . A loudspeaker is not an ideal 8 Ohms resistor, it has some inductance too. So you could even simulate the loudspeaker.

When you see for instance a Push Pull EL34 amplifier working for the first time in LTspice, it will probably amaze you totally, and inspire you very much. Such an LTspice schematic is on the Duncan Amps site. Also some great freeware like PSU designer by Duncan is written with spice. However PSU designer is a higher level of programming, and you do not recognise any more, it is Spice.

The best resource to my opinion is: http://www.dmitrynizh.com/

List of good Links for SPICE PARAMETERS

=> Free Download of Spice Simulator Program. Download only the original from Analog Devices..


Duncan Amps


Random links about Spice Paramaters