• 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.

4P1L triode PP (40W!!?)

I am new in LTspice. For very first simulation I made PP with 4P1L in triode. I do not know if my simulation is OK. I got 40W (!!?) and 1% THD.

Is my schematic and meauser OK? Please comment.
 

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Shoog

Member
2002-08-15 10:16 pm
Eire
Models fail to detect faulty start conditions. Thats where the users intelligence is essential to understand the limitation of the model. Spice doesn't understand power limits - it simply amplifies within the parameters of the valve stages and the input conditions. As was pointed out - your mistake was to input far to much signal to the outputs.

Shoog
 
Models fail to detect faulty start conditions. Thats where the users intelligence is essential to understand the limitation of the model. Spice doesn't understand power limits - it simply amplifies within the parameters of the valve stages and the input conditions. As was pointed out - your mistake was to input far to much signal to the outputs.

Shoog

I did not know that. Thanks for info.
 

45

Member
2008-12-18 2:29 am
UK
I am playing with this schematic for several days. I know that the 4P1L is "only" 10W, but I am curious why I get this result. Because of schematic? Because of tube model? Or beause LTspice does not work 100%?

As already pointed out you cannot drive the 4P1L's with 260V signal. As it is a simulator valves will not get red hot and the amplifier won't disintegrate. This is not a fault of LTspice but yours. It will work as long as you feed it with sensible numbers....
Also 1K8 load is just too low.
I don't know if Ale has refined the model for positive grid region but it should be fine up to +10V grid voltage (except for the driver requirement of power drive). It is surely based on real curves. This means that if your bias is -24V you should only apply no more than 78V peak-to-peak signal to the grid not 260!
 
Last edited:
As already pointed out you cannot drive the 4P1L's with 260V signal. As it is a simulator valves will not get red hot and the amplifier won't disintegrate. This is not a fault of LTspice but yours. It will work as long as you feed it with sensible numbers....
Also 1K8 load is just too low.
I don't know if Ale has refined the model for positive grid region but it should be fine up to +10V grid voltage (except for the driver requirement of power drive). It is surely based on real curves. This means that if your bias is -24V you should only apply no more than 78V peak-to-peak signal to the grid not 260!

Something like this (14W)?:
 

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I don't know if Ale has refined the model for positive grid region but it should be fine up to +10V grid voltage (except for the driver requirement of power drive). It is surely based on real curves. This means that if your bias is -24V you should only apply no more than 78V peak-to-peak signal to the grid not 260!

I haven't refined the model for A2 operation as I don't have(yet) grid current traces. I have recently refined a model for the 814 and 4-65a in triode mode as transmitting valves generally have grid current curves available. Dmitry refined the grid current model replacing the classic diode one with a better curve model which matches the exponential grid current at lower anode voltages.

I will publish these new models when I get the time.

The new 4P1L model performs more accurately than Dmitry's at larger voltage swings, but clearly will not represent A2 operation well...
Ale
 
I was getting 5W from one paralleled pair in A2. You can't get more.
Soviet push-pull amp that used one 4P1L as a driver with interstage transformer driving a pair of 4P1L was rated for 10W output. However, it was battery powered, so I don't expect high idle current.

КРУ-10

[IMGDEAD]http://www.rw6ase.narod.ru/000/rez2/kru10_04.jpg[/IMGDEAD]

[IMGDEAD]http://www.rw6ase.narod.ru/000/rez2/kru10_06.jpg[/IMGDEAD]

[IMGDEAD]http://www.rw6ase.narod.ru/000/rez2/kru10_05.jpg[/IMGDEAD]


Schematic on page 21, including details of transformers: http://piratbooks.ru/file/_zhurnal_Radio_Radio_1952_09.djvu
 
Thats unfortunate.

Why OTs would be needed in struggle for liberation of working class of the planet from capitalist exploitation? :)

Power transformers, though, were great. ТА, (Anode Transformers), ТАН (TAN, Anode and Filament Transformer), ТН (TN, Filament Transformer), ТПП (TPP, for powering of semiconductors)

[IMGDEAD]http://www.radiolibrary.ru/reference/transformers-tpp/TPP245-razmery.jpg[/IMGDEAD]