ok thank you very much for the information, and all the review, but it is not really the answer you expect but if I am interested in doing the phabb tone, it is good to have a tone shapping in a small format, really I have not bought the boss katana yet, simply I tried it and said for 25w it sounds decent, and well I had the idea of making a preamp to use it there although the preamp that I like the most is the hiwatt one. The reason why I exposed the Alembic or Fender Bassman one is because it is simple as far as it goes and I more or less wanted them to explain to me how to find the cutoff voltage and all the other parameters to be able to carry out other projects later. but the pahbb tone to start is excellent I will do it.

PD:but now that he's telling me about the katana, I think I'll back off and look for another amp that meets my expectations, thanks, it just saved me from a tantrum hahaha

Thanks phill

Well, maybe I didn't express myself in the best way, my bad, I want to use the preamp as a pedal in the smallest possible format, to connect it to the power section of a katana boss 50/25w it would be more or less comp>dist&over>modulations>preampF2B> delay>reverb>rotaryspeakersim>powersectionkatanaboss more or less like that I should also experiment to get the best results, and honestly I don't want to use the tubes because of the time limit of hours uses and everything else, besides I want to learn about this for use it for future projects

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Hi, I'm new to this community, I'm looking into famous preamp stages and I found a job done by KMG with the depletion mode LND150 mosfet, I'd like to be able to do it but honestly I don't know anything about electronics and working with those high voltages I have a greater respect then I am in these places to see if someone could help me to get the best results, I do not ask them to carry out the project but if they guide me, and where I live I can find someone who knows about electronics and works with those voltages that mount me all work.

The preamp stage I would like to make is the alembic f2b stage by adding a source follower at the end of the second stage to run it with long cables. for source follower stage use this work https://amtelectronics.com/new/articles/Source_follower_HV_mosfet_as_cathode_follower.pdf

On the other hand, I attach the schematic with the lnd150, the only thing missing is to get the values ​​of the resistors in the -Vbias circuit and the capacitor, thanks in advance.

http://file:///C:/Users/marti/OneDrive/Desktop/Claudio/AFET2B2.png

P.D: If there are problems with the link, send me your emails and I will provide you with the schematic.