If you are up to it the Lab series of amps like the L5 is supposed to be a nice amp that's all solid state, you can buy the PCB for a stomp box build for a dual channel one or each single channel separately.
https://aionfx.com/project/l5-preamp/
https://aionfx.com/projects/
Just look up Preamps and the schematic is usually in the build documents.

There are a number of Marshall solid state amps you could try, but the mosfet ones you would most likely have to make a different power amplifier as the 2SJ49 & 2SK134 mosfets are very hard to get.
Orange Crush 20 looks like its fairly simple.
Roland Cube 20 might be ok.

If you want to learn to make your own PCB's I would suggest KiCad software, it is free and there are no restrictions on what you can make with it.
https://www.kicad.org/

Are you going to build it with vero board or are you after a PCB to build the amp ?
Are you able to make your own PCB ?
Are you going to want reverb ?
Are you after clean tones or overdriven like Marshall etc?
It all depends on what sort of music you like to play.

There are some pre-amplifier pedal kits around if you want to go that way.
You would need a separate power amp pedal to go with the pre amp pedal.

You will need to provide a little bit more information so we know what you will like to build.

And lastly, welcome to the forum.

A lot of older amps have all transistor power amps in them, like the Marshall 12watt amps, Marshall 20watt and 30watt amps. They used Darlington power transistors in some of them.

Randal RG100 has all transistor pre-amps I think.
Yamaha G50 is all transistor apart from the reverb tank.
Roland Blues Cubes used to be all transistors except for one IC for the reverb tank.

Lets not forget the fantastic Albert Kreuzer 2002 BASS JFET Preamp, it might be re-voiced for guitar but might be too clean sounding.

Hopefully someone more experienced can make some suggestions of all transistor pre and power amps.

Just search around for some old schematics and borrow parts of them and get the breadboard out and experiment.

Also if you have some 4069 hex inverters or similar they can be used as Op-Amps.
Sunn Beta used the 4069 chip, and I know there are others that used them as well.

https://www.drtube.com/marshall-jmp-solid-state/
https://www.drtube.com/marshall-jcm800-solid-state/
https://music-electronics-forum.com/forum/amplification/solid-state-hybrid/923640-why-does-cmos-get-such-a-bad-rap/page2

Good luck, I will be interested to see what you do.
Cheers
Mick

 

It seems there are a few around with the same problem.
https://www.tdpri.com/threads/orange-crush-35rt-speaker-buzz.834557/
https://www.reddit.com/r/orangeamps/comments/zyl3y0/35rt_constant_buzz/

Is the 24v 40VA transformer centre tapped, or is it just one output of 24v?
If you have 12v + 12v it would make it easier I think.
Do you have any Op-Amps or will it be all transistors?

There are lots of old transistor amp schematics around that you could borrow sections from, maybe a proven pre-amp that sounds good already.

It all depends on what transistors you have, I would like to see just the part numbers, I don't need to see the specs for each one.
Cheers
Mick

I keep thinking/hoping that Phil plays Bass guitar with a moniker like PHATT, Phatt just makes me think of a deep fat bass riff being played.

I know its made up from parts of his name, but still, what a cool name for a bass player.

I totally agree with Phil, somewhere between the volume pot and IC102.
It would be best before or after R131, if the picture I found on the net is correct then there are 2 PCB's in that amp.
I would find the correct wire between the pre-amp PCB and the power-amp/ power supply PCB and cut that wire to install the 2 Jacks.

I think I spy a shorted track ?You cannot view this attachment.

The 2N3819 is a JFET transistor, you are looking at an old style TO-9 one in your amp, the new ones look different in the TO-92 casing.
You can still buy the old style one if you shop around, but I would not.
New ones are more likely better quality.

https://electronic-studio.com/2N3819-JFET-N-Ch-25V-005A-035W_1

https://www.digikey.com/en/products/detail/nte-electronics-inc/2N3819/11647880

Guzzies3, have you considered trying to build some of BajaMans Pre-Amp pedals from https://www.freestompboxes.org ?
Some of those can work well in front of an amp I believe.
He has made Amp sims for several different amps as well as speaker sims etc.
They all have vero board layouts for them.
I made up some of them as PCB's but I havent had time to make any yet.

As far as hijacking a thread goes, I don't think Joecool85 minds it happening, at least I hope he doesn't.
As long as it is in a friendly manner and it keeps this site as a friendly forum where like-minded people can have a chat and share ideas and stuff.

Michael

Enzo was a great man, he was always helpful AND informative.

Most of the time when Enzo gave you an answer he also explained it so you learnt something.

He always made me think of the old saying:
Give a man a fish and you feed him for the day.
Teach a man to fish and he has food for a lifetime. (or something like that)

Guzzis3, where are you getting the Hotone Boogie Siva for $72 from ?
I might be interested at that price.

I am not worried if this topic has drifted a tiny bit of topic, and I started it.
As long as I find out new things I'm happy.

I am especially happy now since I have found out about the Hotone Nano series.

Michael. 

Thanks Phil for pointing out the JC models page, I have just finished reading it for the second time and it was very informative.
I have also re-named the JC-100 84 file to head only single channel.

I would do what Phil said regarding the effects loop, ignore what I said.  

Phil, unfortunately Enzo passed away in August last year.

https://music-electronics-forum.com/forum/music-electronics/967156-rip-enzo

I had a look through my files and found a 84 JC120 schematic with an effects loop,
if you compare the circuit after the return jack you will understand what I meant above.

Never mind, that's a single channel head only.  (Thanks Phil)