. I've got a few other projects to finish up before I get started actually building a Wreck unfortunately. Right now I like building guitar amps out of old PA chassis' and I've gotten quite good at it, but I've run into a bit of a problem with the last one I did.It started out as a Bogen K15 with a pair of 6L6GBs, I replaced them with 5881s right away. I figured in this amp I'd play around with a paraphase PI design since I never have before. Well, that turned out to be a nightmare. Really harsh, ugly distortion out of the PI, I've replaced most of the components in there many times over and I've concluded the paraphase is not for this amp and I want to switch to an LTP. You probably can see where this is headed.
The amp runs the output tubes at a fairly low voltage (350-ish if I recall) and I've got 6V6s in there right now with no problems so I think I'm gonna stick with those. I was flipping through some schematics to get some ideas for the new PI design when I remembered the Express can run 6V6s and sounds pretty good with them. I've got kind of a "standardized" two-stage preamp that I like to use and the second stage slams the PI pretty hard so I'm guessing the Express's would cooperate much better than the paraphase. I actually prefer that preamp with SE amps because when it's cranked a vast majority of the distortion is from the power tube but I was hoping I could get it to work with a push-pull amp as well.
Anyway, the amp is cathode biased and I hardly have room in the cramped chassis (it's all point-to-point) for tweaking the PI let alone adding a bias supply. Has anyone tried a cathode-biased Express-style output design? Any other thoughts?
Thanks.
-Darren
Edit: Said "cathodyne" and meant "paraphase". Sorry if that confused anyone.
