Tubelab;
As you know I have been kicking around some ideas for both a preamp/crossover and a SE power amp for the high frequency drivers (above 150Hz) in my system. The more I think it over I am drawn to something similar to your simpleSE except that I would be using point to point wiring, no GNF and no CCS.
I am inclined toward the edcor 5K open frame with switchable UL and I like your idea of relatively high B+.
In your write up you state that you needed CCS with the 12AT7 to get enough gain. It seems like the CCS might not be needed if no FB is used as there will be no feedback losses. Do you have a feel for whether a resistively loaded AT would have adequate gain to drive EL34 or 6550?
You also mentioned that a couple of obvious choices in higher gain tubes (12AX7 and 6SL7) would not provide the frequency response that you needed because of capacitive loads of the output stage. Is that because the maximum cathode current is too low to drive the C load or because of low Gm (or is that the same thing in effect)?
Would paralleling the dual triode sections solve that problem or are we still short?
I appreciate your patience with a rookie's questions. I don't really understand how you calculated the necessary drive for a particular frequency response.
mike
As you know I have been kicking around some ideas for both a preamp/crossover and a SE power amp for the high frequency drivers (above 150Hz) in my system. The more I think it over I am drawn to something similar to your simpleSE except that I would be using point to point wiring, no GNF and no CCS.
I am inclined toward the edcor 5K open frame with switchable UL and I like your idea of relatively high B+.
In your write up you state that you needed CCS with the 12AT7 to get enough gain. It seems like the CCS might not be needed if no FB is used as there will be no feedback losses. Do you have a feel for whether a resistively loaded AT would have adequate gain to drive EL34 or 6550?
You also mentioned that a couple of obvious choices in higher gain tubes (12AX7 and 6SL7) would not provide the frequency response that you needed because of capacitive loads of the output stage. Is that because the maximum cathode current is too low to drive the C load or because of low Gm (or is that the same thing in effect)?
Would paralleling the dual triode sections solve that problem or are we still short?
I appreciate your patience with a rookie's questions. I don't really understand how you calculated the necessary drive for a particular frequency response.
mike