The Design

So I wanted to build a small amp and looked to the Vox AC4 for the basis of my design. It's a pretty simple, single ended class A circuit and when you cut out the fluff like the tremolo circuit, there's really not much to it. 

This is the schematic I started out with for the AC4.

Vox AC4 Schematic

So I decided, if I take out the tremolo circuit, what can I add? When I was looking around for schematics on the AC4, I came across this absolutely amazing site. Enginerd DIY Tube Amps. This is where I got the idea to add in a top boost channel into my design. Except in his design, he skimped out on the cathode-follower. I've decided to include it even if I do have an unused triode... room for a future project?

What I've got in my head now is more of an AC30 that runs at the power level of an AC4. What I did next was take the top boost channel from the AC30 and the AC30's EF86 channel which is now in the AC4 and put them together. The two channels are mixed together as Vox did by using 220k resistors to feed into the next amplifier stage. In the AC30, this would be the phase inverter but I'm running single ended so my next amplifier stage will be the AC4's power amp.

Power supply time. I ditched the AC4's power supply design and went with the AC30's. I'm not sure what to expect really in terms of voltage levels. If things are too out of whack, I'll switch the choke in place of a 1k ohm resistor to calm things down. But, the transformer I ordered for the job has a smaller winding ratio that the AC30's so I think things will balance out. 

So this is what I ended up with as a schematic. I made an effort to use proper layout software like Eagle or Altium but sadly the best and easiest results came from MS Paint (I am so ashamed of this fact). Designed by a first time tube amp builder and is not guaranteed to even turn on.

AC4TB Schematic