My first amp build was a 5F2-A Princeton. It was fun, but produced a rather worthless amp = a glorified Champ useful only for practice at home. So I built a 5E5-A Pro for gigging, leaving me with the Princeton as a work bench for modding. I added, well, everything: 5E3 circuit, OT, tubes, and 12" Jensen alnico P12Q speaker (read: a single channel Deluxe), producing a bassy distortion machine, not to my liking at all. I messed around with many different resistors and capacitor values trying to clean it up with little success. Eventually I put it back to stock except for V1, which I kept as 12AX7 run in parallel with 1K cathode resistor and 10uf capacitor (amplification of the 12AX7 but fatter and more headroom). So I added a 5F11 Vibrolux power transformer (bolts right into the 5F2-A chassis!), fixed bias, a choke, and NFB (meaning a 5F10 Harvard with a choke). That sounded MUCH better, particularly with RCA blackplate 6V6GT's. My only concern now was an overdose of B+; I had 406v where 300v would be more suitable. I was looking for ways to drop the B+. I already had 5Y3, so no lower rectifier available. Maybe a big power resistor between the rectifier and the filter capacitors?... Then the simple solution hit me - use the extra power! I checked the specs on the 5F11 transformer against Weber's Prolux amp schematics: it would work just fine. This morning I put in old Sylvania 6L6GC's I had hanging around. WOW! Perfection! The result is small and lightweight like a 5F2-A Princeton with the power of a 5E5-A Pro and the warmth of a 5E3 but cleaner, tighter and lots of chime. Plenty of power for gigging. I can run it wide open and control breakup, tone and volume with my pinky on the Tele. This recipe makes for a really good working amp. I will post images, but warn that this was a prototyping hack job - aint gonna get the super clean build award.