Power MOSFET into tube amp.

[psychepool]

Power MOSFET is often used in tube amp, especially non-gain section.(ex : fx loop, reverb driver...etc)
But in preamp section(The gain stage, and cathode-follower...etc.), it's hard to find.


I like to make mid-wattage(20~40W) amp compactly.
When I plan a circuit, I'm often faced with the situation that insufficient single triode.
In this case, I thought that replace the triode with power MOSFET.
It can save the space for a tube.

In fact, I'm already posted the similar question in other board.
https://tubeamparchive.com/viewtopic.php?t=29277
But I don't want to confine this content just in Marshall circuit, so I post it again on this board with summarized.

What would be happen when replace the triode with power MOSFET?
If replace it without any significant difference, only just in cathode follower, It would be very worth for me.

I expect that there will be very many opinion.
I want to hear a variety of opinions.

Thanks.

[Littlewyan]

Following on from the other thread I do recall someone once managed to get a MOSFET to behave similar to a valve. I will try and find the article later. Basically they got it to bottom out like a valve and thus would distort.

[SilverFox]

Why does it have to be a "Power Mosfet" as opposed to a signal level Mosfet?

silverfox.

[pdf64]

It would probably need to be a power MOSFET if it's for the reverb driver.
I think that RG notes that these are likely to put a capacitive loading on the preceding circuit, so that would likely need accommodating to avoid it causing a problem.
So probably best to use a small MOSFET where possible.
They're much smaller too!

[psychepool]

Following on from the other thread I do recall someone once managed to get a MOSFET to behave similar to a valve. I will try and find the article later. Basically they got it to bottom out like a valve and thus would distort.

Oh, I also wanted to find the related post but i was failed. Thanks for your favor!

[psychepool]

I found this article

http://www.blueguitar.org/new/articles/ ... i_v_ss.pdf


Follow this article, it can be almost direct replaced with Powered MOSFET in cathode follower circuit but in other circuit, needs some devices for operate it.

SS circuit seems complex than antique tube circuit.

[teemuk]

http://www.sugardas.lt/~igoramps/article68/article.htm

http://milas.spb.ru/~kmg/tubeemulation.html

http://gtlab.net/gtlab4/archives/216