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- last updated 22/07/00 18:02:58


Spice Models of Vacuum Tubes

Here are models of a few popular audio tubes that have been generously donated by others*. (If you have any working models that you would like to add, please let me know.)

general model for the heater of indirectly heated tubes





... and we even provide some example files.
curves-300b.cir 300B curves

rca-riaa-amp.cir phono preamp with RIAA equalization from RCA.

... or, you can get all of them zipped up together.

If you see any of the following people, thank them heartily for contributing models!

Francesco Piazzo
Duncan Munro

Although I use PSpice occasionally, I have not tried these and cannot offer much help with them. However, Francesco has told me that he would not mind offering some support, time permitting. So if you have a question that is not too much trouble to answer, or would like to discuss Spice modeling of vacuum tubes, send him a note: Francesco Piazza (

Norman Koren has written two wonderfully detailed and informative articles for Glass Audio magazine[1]. Anyone with a serious interest in using Spice to model vacuum tube circuits should obtain a copies of his article (see below about contacting Glass Audio.) Mr. Koren has graciously offered the Spice source code to anyone that drops him an Of course, you'll still need to get the GA article to make sense of them.

Intusoft has made available some free IsSpice models of vacuum tubes. Visit their web site and look for newsletters #34 and #35.

If you have other Spice models of vacuum tubes (even the same tubes) please let me know. I would like to add them to the list!

Some references for spice modeling of vacuum tubes

1. Norman L. Koren, "Improved Vacuum Tube Models for Spice Simulations," Glass Audio, 5/96, p. 18.

2. Scott Reynolds, "Vacuum Tube Models for PSPICE Simulations," Glass Audio, 4/93, p. 17.

3. W. Marshall Leach, jr, "SPICE Models for Vacuum-Tube Amplifiers," J. Audio Eng. Soc., Vol 43, No 3, March 1995, p. 117

4. Charles Rydel, "Simulations of electron tubes with Spice," AES preprint 3965 (G1), 1995.

Glass Audio back issues and subscriptions are available by contacting their Circulation Department at 603-924-9464 (voice), 603-924-9467 (FAX), email:, or write to Glass Audio,305 Union St., PO Box 176, Peterborough, NH 03458-0176, USA. Help support this fine publication by subscribing or purchasing back issues rather than asking for photocopies of articles.

Sources of free Spice software.

There are two companies that offer free "evaluation" versions of Spice software: MicroSim offers PSpice, and Intusoft offers IsSpice. It seems that PSpice is more commonly used (Francesco's models are PSpice models), but some people have reported that IsSpice is more powerful. I have very little personal experience with either (and no time to learn!), so please don't expect me to be of any help deciding which to use. My best advice is to try them both. If it tilts your decision, Charles Hymowitz of Intusoft has a lot of experience modeling tubes and has offered his help for all types of Spice support (IsSpice, PSpice, or any other brand of Spice.)

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