preamp schematic modification from transistor to tube: is it possible???

[herromynameree]

Hi guys, this is first post on this my first post on this forum, and I don't know an awful lot about what I am going to ask, so please don't be too hard on me!

I have found a schematic for a solid state fender-style preamp from redcircuits.com, and I want to have a crack at building it. It is the most simplistic preamp schematic I have found on the internet, but I do wish I can just be able to switch one or two transistors for some 12AX7s. Is it possible? And if so, am I able to just keep in the two transistors after the tone stack? Thanks!

[tonyharker]

Why not just make a copy of the real Fender blackface preamp?

[11-90-an]

Welcome to the forum...

I agree with tonyharker. Why not use the original? Here's the schematic of the tube one...



The tube version use only one tube. If you have some, why not do this?
Just note that the origianl tube vesion runs on 360v and the JFET version runs on 18-30v...

Whatever you do... stay safe!

[Marcos - Munky]

Welcome to the forum.

I also agree with them both. Just go for the original Fender preamp (which also happens to be the Alembic F2B preamp). Single tube, awesome sound. I built one to use with a pair of ECL82 in push pull, and the clean sound is just amazing, now I'm building another one for a friend. Also, you can power it with a proper transformer, 2 transformers set to "back to back" configuration, or even the 555 smps set to something like 200V. For a very compact (and safer than the other options) build, go for the smps.

Btw, check this: http://www.gilmourish.com/?page_id=71

[cab42]

If you want to make it a bit easier for yourself with the F2b, you can buy a pcb ready for use.

I have bought one from user Vigilante397, called the Particle Accelerator https://www.sushiboxfx.com/product-page/particle-accelerator-pcb-th. Some info here on a F2B with some bells and whistles: https://www.diystompboxes.com/smfforum/index.php?topic=120628.0

I have also heard good things about Frog Pedals frogpedals.com Lots of information in the build doc: https://frogpedals.com/wp-content/uploads/2020/04/FrogTubeAmpDocs-2.1.pdf

Both are designed with subminitubes in mind, but regular tubes can be used as well. 

There are probably others. I believe user gtudoran had one as well, but I can't find it.

[vigilante397]

If you want to make it a bit easier for yourself with the F2b, you can buy a pcb ready for use.

I have bought one from user Vigilante397, called the Particle Accelerator https://www.sushiboxfx.com/product-page/particle-accelerator-pcb-th.

I still have a bunch of those around, but if you want one I'm afraid it will be about a month as everything in my workshop is packed into boxes that I don't feel like opening

[herromynameree]

Thank you all so much for your help! I wasn't able to see the schematic of the original preamp when I first was looking it up, everything that I saw was just all transistor blackface preamps.