I just finished a build of a custom harp amp. It's based on the Fender 5c4/5d4 schematics with some tweaks here and there to modernize the circuit and make it as simple as it could be in terms of "just-plug-in-and-blow-ability." All in all, I think this thing turned out really "super" if you catch my drift
Rather than post all the gory details here and repost the same info on four different forums, I created a blog entry complete with a demo song featuring the amp and background info on why I built it in the first place.
MakerDP: "Sonhouse Super Harp" Amplifier Build
I'm not really a regular here and I hang-out mostly on AX84. However, since I got a bit of information for this build from this board I thought I should share this with you all. There is very limited information out there on harp amp building. Some of the info floating around the web is just downright not altogether correct so it's hard to sift through it all. MEF seems to be the best repository of original knowledge and pointers to other good sources available on the web, so here is my contribution.
So, thanks everyone for looking and/or contributing to this forum!