Hi Philefreak. My response to you was not meant in any derogatory fashion, and I apologize if it came across as such. (I re-read my response to you and cannot figure why I got such an insulting response from Jeffry)
In my response to you I simply wanted to state that by triode strapping a pentode you do not compromise the tube in anyway, in fact no matter how you configure it, it still runs as a pentode/tetrode.
A pentode/tetrode needs to have it suppressor and screen grid biased to +. There are basically three ways to do that. You can bias the grid from the power supply (pentode/tetrode mode), you can bias them from a center tap on the primary winding of the output transformer (ultra-linear) or you can bias them from the anode (triode mode). Why the latter is called triode mode I am not sure as the tube's suppressor and screen grids still function as designed, and as such the tube is still functions as a tetrode/pentode in every respect.
To your point, a triode strapped pentode is not a triode; not by a long shot. (But I cannot see where I supposedly had said anything to the contrary)
It is however, quite handy to have the triode vs. ultra linear switch as allows you to slightly alter the characteristics of the amplifier. As such you can change it to suit the music you play. Most audiophiles normally prefer pentodes to be triode strapped. Personally I prefer pentode/tetrode mode, but I have rewired a number of peoples tube amps to triode for them.
As for pentodes or tetrodes being inferior to triodes, well that is plain ignorance. Most pentode/tetrode amps have cheap components and cheap output transformers. As such they are unimpressive. However, if you ever have the opportunity to hear an amp like an Art Audio Gill (single ended triode strapped EL34) or AudioNote 6550 SE (single ended tetrode) you'll forget any notion of pentode/tetrode being inferior. They can provide fantastic sound given the right design and components that exceed true triodes in some areas.
I'm going on my sound preference alone, not a debate over tube topology correctness.
That makes two of us.
Regards
Paul