Vacuum tube audio amplifier

[frickecello]

Hi, I just downloaded Multisim9 freeware, however the full software is installed in certain computers at the university I study (ITESM), so Im quite familiar with it.

I have problems when I simulate any vacuum tube related circuit, Im using Multisim tube models (mainly 12ax7 and 12au7a tubes), I have the same circuit in other spice software and it works, I have also built the circuit in reality and it works, I want to simulate it to fine tune it...

I have centered the problem to the input of the amp, when using a signal generator, the maximum voltage to make it work is about 5 mV, I think that when the signal is amplified is reaches some tube stage swing limits, and it should clip, (that's what I see in other simulators), and instead of this, a "TIMESTEP TOO SMALL" error appears.

If I input 500 mV it inmediately crashes.

Hope you can help me.

Regards.

[nestor-sg]

A previous message thread:

http://forums.ni.com/ni/board/message?board.id=370&message.id=266

Helped to file a report for EWB R&D that the spice model used in the component database is conflicting with the spice engine of Multisim. R&D will fix it in the short-term. Is currently not working properly.

[chosborne]

I am also trying to simulate a modern vacuum tube circuit. I get the same convergence issue that the first poster mentioned. I am using Multisim 10.0.1 an Windows Vista. When will NI have this problem fixed so that we can simulate audio tube circuits?