Uberschall differences
For me, the Rev2 is just right. I think great tube amps (high gain or not) should "breathe" and have a "organic" quality to them. This alone is one reason why I'll never sell my early Dual Recto. When using the tube rectifiers on spongy that amp has that quality in spades. Now keep in mind tone and feel are in the eye/ears/hands of the beholder and very subjective.
This is the basic rundown of the Uberschalls:
Original - Fast gain taper on Gain Channel (some have said almost like an Off/On kind of jump in gain), high plate voltage, good power section compression/sag when pushed, Clean Channel volume slightly lower than Gain Channel by comparison, plastic carry handle (although some Original Uberschalls got the leather handle just prior to transitioning into the Rev2), EL34
Rev2 - Reduced gain taper on Gain Channel (same gain, just more controllable), high plate voltage, good power section compression/sag when pushed, Clean Channel volume slightly lower than Gain Channel by comparison, leather carry handle, EL34
Revision Blue - Same basic gain structure, lower plate voltage, less power section compression/sag when pushed, Clean Channel volume matched closer to Gain Channel, re-design of circuits, addition of Loop volume control, bias test points, power jewel changed to smaller LED type, dedicated design ability to allow power section slaving from an outside source (but this can be accomplished on Original/Rev2 versions), EL34
Twin Jet 1.0 - Gain Channel re-design in a direction towards the Original/Rev2 designs, plate voltage unknown at this time so I can't say, less power section compression (due to the design switch to KT88 power tubes), Clean channel re-do in the direction of a high gain modded Marshall tone with very little ability to get a truly clean sound, addition of power section Presence and Depth controls, KT88
Twin Jet 1.1 - The same as 1.0 but with a modded gain taper on the clean channel, same level of gain available as 1.0 with the ability to go lower gain and clean up better
Now keep in mind, I made up TJ 1.0/1.1 for the purpose of comparison , I don't think Bogner looks at them that way. Bogner does offer to perform the Clean Channel mod for anybody who owns what I call 1.0 at no charge.
These are the main differences I know about. I don't know specific component values between the different versions from a design stand point, but I can say my descriptions above, for the most part, are right on the money by way of research, comparisons and the general consensus from those who have had time with them. The volume difference between the Clean Channel and Gain Channel on the Original and Rev2 seem to be exaggerated. Yes there is a difference, but nothing that can't be fixed by just turning the Clean Channel Volume control up a little more than the Gain Channel volume control. Another words, adjust the amp with you ears, not your eyes.
