) Upshot is I'm getting a lot faster with Kicad, if I'm doing a direct copy, I can generally have it done in about an hour. Some of these might be useful just for the sake of the original schematic being a pain to read, particularly in the case of the Legend and the Mesa Mk. II. Though they should be verified and double checked before being used for anything. In all cases I've tried to lay them out in a way that neat and easy to read, though some things can be improved. I don't guarantee the accuracy by any means and I'm sure there's values I've forgotten to fill in and probably a few mistakes. If you spot any let me know and I'll post corrections. Some may not be complete or true to the original circuit. Most of the parts haven't been annotated yet either. Below are the schematics in PDF form and a description of the motivation for each project. -Legend 6v6: I described this one at length in another thread. I still plan on starting it here soon. I just need to get a few other odds and ends taken care of first. I want to get some old stock tubes for my 6v6 Express and Marshall Builds, as well as a beefier OT for the Marshall.
-High Octane PP: From the AX84 site, I always have wanted to give this circuit a try but I've just never gotten around to it. Its another 2203 variant with lots of gain. Stock pre-amp, but PP output with EL84's.
-Supro Model 24: The supposed Jimmy Page amp. This one got into my head while digging through a stash of random old tubes I acquired a long time ago and had forgotten about. Found a trio of GE 6973's, assuming they're good this would be a fun little addition.
-Mesa MkII: This one pretty much speaks for itself. I've always like the MKII most over any of Mesa's designs. It has the best combination of high gain and tone IMO. Would be building it without the reverb or the EQ, which could be made up for with an EQ pedal in the effects loop. This is the schematic I'm the most unsure of. Partly because Mesa has supposedly been known to provide incorrect schematics and partly because its a pain to read and is the most complicated. If the original I was looking at is correct, they did certain things in strange way that I'm not sure I see the logic behind. In any case my amp collection is lacking in the metal department and this and the HO would fill that out nicely.
-5E8A Lower Power Twin w/ Reverb: This is probably the most interesting on the list for most people here. I've been looking at the Tweed combo's over the past year or two on and off in search of one that would be easy to shoehorn a reverb into without having to make a custom chassis or cabinet. It can be done if you don't mind loosing three inputs and whatever interactions they may have had with each other. I've adjusted the cathode resistor on the first stage and the grid leaks on the second to account for this. I think I've come up with a decent scheme for the tube order as well. V1 is the first two gain stages, V2 is the cathode follower and the reverb return, V3 is the reverb driver and V4 the last gain stage and PI. This way the circuit is the least affected by needing a 12ax7 for the reverb return. Since the cathode follower doesn't have any gain, though with a 12ax7 the output impedance will be higher, though I think it shouldn't matter too much as the input impedance to the tone stack should be fairly high in this case. If it does could probably still use a 12AY7 and adjust the divider ratios and the pot value at the output to account for the lower gain. The biggest question is were to insert the sends and return so it has as little effect on the circuit as possible while still maintaining a simple layout. Right now I've got the send at the output of the CF after one of the coupling caps and the return at the output of the tone stack. Not sure how well that will work. I increased the divider by a factor of ten on the output of the return to minimize the loading on the output of the tone stack.
Well there you have it. Again this all just preliminary ideas that have been bouncing around my head the past few months. With the exception of the legend, a lot more consideration and thought needs to go into most of these before being built, but hopefully someone will find them useful or interesting.
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