Here’s another amp built in an Epiphone Valve Junior chassis. Like my other amps, nothing much else of the Valve Junior remains.

I wanted to build something relatively simple but with a fair amount of gain. So I decided to build an amp with 3 gain stages and a cathodyne PI. I went with basically a JCM800 pre amp into a 5E3 PI and output. Actually that’s a very loose description. The PI and PA really only share the cathodyne phase inverter and 6V6s with the 5E3. This amp has a solid state recitifer, a bunch more filtering than a 5E3.

Overall I did a lot less tweaking to this one than most of my other amps and I followed many suggestions from the Tone Lounge. Overall, my thinking was when I needed to decide what value to use in a given location I would go with a Marshall-like value. That seemed to work out fairly well. It would have been more Marshall to have the 3rd stage biased with a 820R resistor but I thought that sounded too fizzy so I went with a Fendery 1.5k/22uf combo.

On the original version there is a conjunctive filter to remove some harshness. I look at the conjunctive filter as a sort of NFB alternative.

It was also nice because I made up the schematic, built it and it worked perfectly the first time firing it up!

Here is the original schematic:




It was done sorta quick but it gives an idea of the sound. I would say more Marshall than Fender for sure. The speaker is a Vintage 30 in a 1×12.


Some pics:

I built the cabinet myself. As if you couldn’t figure that out… The baseboard molding left over from my kitchen adds a nice touch to the front of the amp if I do say so myself.

jcm5e3_cab2 jcm5e3_chas jcm5e3_cab1


    • The clip we recorded with V1, the schematic on this page. I had done some tweaks but I took that down, mostly because it wasn’t what the clip was recorded with.
      I don’t even remember what V2 was but if I was building this again I would probably add a MOSFET follower, a regular marshall tone stack and 47k grid stoppers on the power tubes. Maybe a grid stopper on the PI but there’s already a lot of resistance in the tone stack and master volume.

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