Roscoe Primrose wrote:
Keep in mind that for most SPDT toggle switches, the center contact and the one opposite the position of the toggle are the ones connected together.
Roscoe
Oh, I understand the theory but could not understand what I was hearing. I was thinking that there was a something wrong with the triode mode setup and that it was actually running in pentode mode(which would explain the gain), despite the fact I could see no B+ connections to grids.
I think you answered the question with the info about the switch. So when the switch is switched to the position above the pin connected to the UL tap, it is actually running the other pin (triode mode) and vice versa.
Which means I prefer triode mode over UL mode with my horns. UL mode sounded a bit flat and had a certain harsness to it.
This McGown amp is using global feedback (4 ohm output tap is connected to driver). Probably not needed for UL operation but better for triode mode I guess? Can any PP guys here comment on what has sounded better in their opinion (UL with or without global feedback, triode with global feedback, triode with no global feedback etc). I'll probably play around a bit and see what I prefer but I would think that output stage output impedance would be really high with a pentode operated in triode without feedback? Too high?